WWVB BPSK Receiver Project?

[Brooke Clarke]

Hi:

I sure would like a WWVB BPSK receiver for the new modulation. The processing gains described in the paper John Seamons
linked describes processing gains that are tens of dB above what's possible with the old AM data format. John has also
measures the experimental phase modulation testing, see: http://www.jks.com/wwvb/wwvb.html
The WWB paper "New Improved System for WWVB Broadcast" given at the 43rd PTTI November 2011 is at: http://jks.com/wwvb.pdf

Part of the processing gain comes directly from the BPSK modulation and that amounts to a little over 10 dB improvement,
but there's a further 18 dB gain to be had by accumulating an hours worth of data and processing that.

I'm sure in time there will be plenty of low cost ICs designed to receive the new signal, but my guess is that many Time
Nuts would like to be in on the ground floor. Also NIST probably would like to get reports on the new signal when they
do test transmissions.

How to move forward?

--
Have Fun,

Brooke Clarke, N6GCE
http://www.PRC68.com
http://www.end2partygovernment.com/Brooke4Congress.html

[Poul-Henning Kamp]

In message <4F6116CE.7080809-***@public.gmane.org>, Brooke Clarke writes:

>I sure would like a WWVB BPSK receiver for the new modulation.

I've been playing with SDR and VLF signals for ages. What you
want is an antenna, a 1MSPS ADC and a fast-ish CPU.

One very interesting thing you can do with that, is to make a
buffer 1000 samples long, and continously average the received
signal into it, round-robin format.

That amounts to a comb-filter for every n*1kHz signal, and a
trivial sin/cos multiplicator will give you the phase and
amplitude of every single radiotransmitter on n*1kHz up to
your antialias filter at the same time.

If you have CPU power, you can also receive Loran-C by making the
buffer GRI*10 (or *20, if you want the code) samples long.

I've long thought about building a board with one of the faster
ARM CPUs and a 1MSPS 16bit ADC for this, but nobody else seemed
interested, so I've just used my hacked up rig.

--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk-***@public.gmane.org | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

[s***@public.gmane.org]

Poul-Henning,

Do you need 16 bits or can you get by with a 12 bit ADC?

Have you considered using an FPGA for signal processing? It seems you need a fairly serious CPU to handle that much data.

Didier KO4BB

Sent from my BlackBerry Wireless thingy while I do other things...

-----Original Message-----
From: "Poul-Henning Kamp" <phk-HF+***@public.gmane.org>
Sender: time-nuts-bounces-***@public.gmane.org
Date: Wed, 14 Mar 2012 22:16:38
To: Discussion of precise time and frequency measurement<time-nuts-***@public.gmane.org>
Reply-To: Discussion of precise time and frequency measurement
<time-nuts-***@public.gmane.org>
Subject: Re: [time-nuts] WWVB BPSK Receiver Project?

In message <4F6116CE.7080809-***@public.gmane.org>, Brooke Clarke writes:

>I sure would like a WWVB BPSK receiver for the new modulation.

I've been playing with SDR and VLF signals for ages. What you
want is an antenna, a 1MSPS ADC and a fast-ish CPU.

One very interesting thing you can do with that, is to make a
buffer 1000 samples long, and continously average the received
signal into it, round-robin format.

That amounts to a comb-filter for every n*1kHz signal, and a
trivial sin/cos multiplicator will give you the phase and
amplitude of every single radiotransmitter on n*1kHz up to
your antialias filter at the same time.

If you have CPU power, you can also receive Loran-C by making the
buffer GRI*10 (or *20, if you want the code) samples long.

I've long thought about building a board with one of the faster
ARM CPUs and a 1MSPS 16bit ADC for this, but nobody else seemed
interested, so I've just used my hacked up rig.

--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk-***@public.gmane.org | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

_______________________________________________
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To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

[Attila Kinali]

On Thu, 15 Mar 2012 13:50:08 +0000
shalimr9-***@public.gmane.org wrote:

> Poul-Henning,
>
> Do you need 16 bits or can you get by with a 12 bit ADC?
>
> Have you considered using an FPGA for signal processing? It seems you need a fairly serious CPU to handle that much data.
>

I think Poul-Henning is refering to his AducLoran receiver, which
used a 1Msps ADC [1]. I dont remember what he exactly does with the signal,
but IIRC he uses a 40MHz uC which leaves him with 40 Cycles per sample,
which is quite a lot if you only do just some math calculation to detect
the start of a second...

And unlike with the FPGA, it does not take more time to process 8bit
or 24 bit samples as the uC works with 32bit numbers anyways.


Attila Kinali


[1] http://phk.freebsd.dk/AducLoran/

--
The trouble with you, Shev, is you don't say anything until you've saved
up a whole truckload of damned heavy brick arguments and then you dump
them all out and never look at the bleeding body mangled beneath the heap
-- Tirin, The Dispossessed, U. Le Guin

[Bob Camp]

Hi

If you can handle the data rates for Loran at 100 KHz with a micro, then you
should be able to handle the data rates for something at 60 KHz. My guess is
that a simple "I know what the waveform is now compare it" approach would
not be terribly processor intensive. Put another way, you can easily predict
exactly what the signal will be doing at any instant. You just need to steer
to the error from that prediction.

Bob

-----Original Message-----
From: time-nuts-bounces-***@public.gmane.org [mailto:time-nuts-bounces-***@public.gmane.org] On
Behalf Of Attila Kinali
Sent: Thursday, March 15, 2012 10:26 AM
To: shalimr9-***@public.gmane.org; Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] WWVB BPSK Receiver Project?

On Thu, 15 Mar 2012 13:50:08 +0000
shalimr9-***@public.gmane.org wrote:

> Poul-Henning,
>
> Do you need 16 bits or can you get by with a 12 bit ADC?
>
> Have you considered using an FPGA for signal processing? It seems you need
a fairly serious CPU to handle that much data.
>

I think Poul-Henning is refering to his AducLoran receiver, which
used a 1Msps ADC [1]. I dont remember what he exactly does with the signal,
but IIRC he uses a 40MHz uC which leaves him with 40 Cycles per sample,
which is quite a lot if you only do just some math calculation to detect
the start of a second...

And unlike with the FPGA, it does not take more time to process 8bit
or 24 bit samples as the uC works with 32bit numbers anyways.


Attila Kinali


[1] http://phk.freebsd.dk/AducLoran/

--
The trouble with you, Shev, is you don't say anything until you've saved
up a whole truckload of damned heavy brick arguments and then you dump
them all out and never look at the bleeding body mangled beneath the heap
-- Tirin, The Dispossessed, U. Le Guin

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[Poul-Henning Kamp]

In message <20120315152620.8347488e049854218aed4aa6-***@public.gmane.org>, Attila Kinali w
rites:

>> Do you need 16 bits or can you get by with a 12 bit ADC?

In general: The more the merrier, for a digital dude like me, having
more bits is easier than getting AGC working correctly :-)

>> Have you considered using an FPGA for signal processing? It seems
> you need a fairly serious CPU to handle that much data.

I have considered FPGA, DSP would probably be more suitable, but
if I can do it in an ARM with C/Assy code, I prefer that.

>I think Poul-Henning is refering to his AducLoran receiver,

That's one of the few experiements I bothered to document, I've been
doing similar stuff with DCF77 phase-code etc.

As long as you're after time/freq, you can use very deep averaging
which only takes a few instructions per sample, so for instance
the 42MHz Aduc7026 chip copes nicely with a single Loran-C signal.

I think I could squeeze a Loran-C navigation solution into it, if
I wanted to and as long as we're not talking too high speeds (again
allowing deep averaging) but I have not bothered.

A modern PC has a lot of computing power for stuff like this, and
is great for prototyping code, before dumping into a smaller chip.

That's how I found out that the circular-buffer averaging comb-filter
is a much better and stronger signal discriminator than almost anything
else you can come up with, for frequency/phase reception.

See for instance: http://phk.freebsd.dk/loran-c/CW/

--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk-***@public.gmane.org | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

[Chris Albertson]

On Thu, Mar 15, 2012 at 3:13 PM, Poul-Henning Kamp <phk-HF+***@public.gmane.org> wrote:
> In message <20120315152620.8347488e049854218aed4aa6-***@public.gmane.org>, Attila Kinali w
> rites:
>
>>> Do you need 16 bits or can you get by with a 12 bit ADC?
>
> In general: The more the merrier, for a digital dude like me, having
> more bits is easier than getting AGC working correctly :-)
>
>>> Have you considered using an FPGA for signal processing? It seems
>> you need a fairly serious CPU to handle that much data.


"That much data" we are talking about 192K samples per second. I can
routinely record multiple tracks of 192K audio and do processing in
real time and the CPU meter hardly moves the bottom. Even a
gigabit per second Ethernet port is not "a lot of data" on a modern
computer.

FPGAs and DSP come into play if you are talking about tens of millions
of samples per second with data rates above say 200Mb/Sec But the
rate from an audio interface running 192K and 24-bits is still under
one megabyte per second. An interesting ratio is the number of CPU
cycles available to process one sample. On my Apple iMac that would
be about roughly 200,000 operations per data sample.

In real life SDR receivers even an older CPU can process the I and Q
channels and maintain a large graphic screen and send and receive data
over a network and still not be "maxed out"


Chris Albertson
Redondo Beach, California

[Azelio Boriani]

PHK,
I'm interested in your circular averaging buffer: suppose 1K long, the 1st
sample goes into position 0, the 2nd into 1 ... the 1000th into 999 or, the
1st gets scaled and then summed with that already present in position 0
then the result back in position 0? And so on, of course, for position 1, 2
...

On Thu, Mar 15, 2012 at 11:48 PM, Chris Albertson <albertson.chris-***@public.gmane.org
> wrote:

> On Thu, Mar 15, 2012 at 3:13 PM, Poul-Henning Kamp <phk-HF+***@public.gmane.org>
> wrote:
> > In message <20120315152620.8347488e049854218aed4aa6-***@public.gmane.org>, Attila
> Kinali w
> > rites:
> >
> >>> Do you need 16 bits or can you get by with a 12 bit ADC?
> >
> > In general: The more the merrier, for a digital dude like me, having
> > more bits is easier than getting AGC working correctly :-)
> >
> >>> Have you considered using an FPGA for signal processing? It seems
> >> you need a fairly serious CPU to handle that much data.
>
>
> "That much data" we are talking about 192K samples per second. I can
> routinely record multiple tracks of 192K audio and do processing in
> real time and the CPU meter hardly moves the bottom. Even a
> gigabit per second Ethernet port is not "a lot of data" on a modern
> computer.
>
> FPGAs and DSP come into play if you are talking about tens of millions
> of samples per second with data rates above say 200Mb/Sec But the
> rate from an audio interface running 192K and 24-bits is still under
> one megabyte per second. An interesting ratio is the number of CPU
> cycles available to process one sample. On my Apple iMac that would
> be about roughly 200,000 operations per data sample.
>
> In real life SDR receivers even an older CPU can process the I and Q
> channels and maintain a large graphic screen and send and receive data
> over a network and still not be "maxed out"
>
>
> Chris Albertson
> Redondo Beach, California
>
> _______________________________________________
> time-nuts mailing list -- time-nuts-***@public.gmane.org
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>

[Chris Albertson]

That would be big expensive filter. All you really need is the
average of the last N samples.
But with WWVB the bits are amplitude modulated at one bit per second.
so you want a big time constant on any AGC, maybe 100 seconds. If
you are sampling at 192K that would use way to much memory if you
stored each sample. Better to only keep running statistics. For
AGC you don't need to process every sample, you can feed the AGC a
subset of the sample stream. But with a 24b-t ADC you may not need
AGC

On Thu, Mar 15, 2012 at 4:01 PM, Azelio Boriani
<azelio.boriani-***@public.gmane.org> wrote:
> PHK,
> I'm interested in your circular averaging buffer: suppose 1K long, the 1st
> sample goes into position 0, the 2nd into 1 ... the 1000th into 999 or, the
> 1st gets scaled and then summed with that already present in position 0
> then the result back in position 0? And so on, of course, for position 1, 2
> ...
>
> On Thu, Mar 15, 2012 at 11:48 PM, Chris Albertson <***@gmail.com
>> wrote:
>
>> On Thu, Mar 15, 2012 at 3:13 PM, Poul-Henning Kamp <phk-HF+***@public.gmane.org>
>> wrote:
>> > In message <20120315152620.8347488e049854218aed4aa6-***@public.gmane.org>, Attila
>> Kinali w
>> > rites:
>> >
>> >>> Do you need 16 bits or can you get by with a 12 bit ADC?
>> >
>> > In general: The more the merrier, for a digital dude like me, having
>> > more bits is easier than getting AGC working correctly :-)
>> >
>> >>> Have you considered using an FPGA for signal processing? It seems
>> >> you need a fairly serious CPU to handle that much data.
>>
>>
>> "That much data" we are talking about 192K samples per second.   I can
>> routinely record multiple tracks of 192K audio and do processing in
>> real time and the CPU meter hardly moves  the bottom.    Even a
>> gigabit per second Ethernet port is not "a lot of data" on a modern
>> computer.
>>
>> FPGAs and DSP come into play if you are talking about tens of millions
>> of samples per second with data rates above say 200Mb/Sec  But the
>> rate from an audio interface running 192K and 24-bits is still under
>> one megabyte per second.    An interesting ratio is the number of CPU
>> cycles available to process one sample.  On my Apple iMac that would
>> be about roughly  200,000 operations per data sample.
>>
>> In real life SDR receivers even an older CPU can process the I and Q
>> channels and maintain a large graphic screen and send and receive data
>> over a network and still not be "maxed out"
>>
>>
>> Chris Albertson
>> Redondo Beach, California
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts-***@public.gmane.org
>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
> _______________________________________________
> time-nuts mailing list -- time-nuts-***@public.gmane.org
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



--

Chris Albertson
Redondo Beach, California

[Poul-Henning Kamp]

In message <CABbxVHv0ZOmcwO6A1r8XRXjQ=v-rQw4dQorL9X8VA1qXA0rb4Q-JsoAwUIsXosN+***@public.gmane.org>
, Chris Albertson writes:

>That would be big expensive filter. All you really need is the
>average of the last N samples.

Expensive ? 2kB of memory ? Not even close to expensive.

> But with a 24b-t ADC you may not need AGC

16 bits has meant that I never needed AGC.

--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk-***@public.gmane.org | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

[Poul-Henning Kamp]

In message <CAL8XPmM+O0EP7yK7mUC16urmyBesWb+wR4UyJd5LrhLCSbWt=***@mail.gmail.com>
, Azelio Boriani writes:

>I'm interested in your circular averaging buffer: suppose 1K long, the 1st
>sample goes into position 0, the 2nd into 1 ... the 1000th into 999 or, the
>1st gets scaled and then summed with that already present in position 0
>then the result back in position 0? And so on, of course, for position 1, 2
>...

Yes.

And once you have filled a few seconds into the buffer, you can multiply
each of the 1000 locations with a n*sine and n*cosine, and sum the results
and you have a phase vector for the signal at n KHz.

For signals like DCF77 on half kHz grid, you need a 2 msec = 2000 samples
long buffer.

--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk-***@public.gmane.org | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

[s***@public.gmane.org]

I was not concerned about processing power on a PC (or Mac for that matter) but for the uC that was used in PHK's project.

Didier KO4BB


Sent from my BlackBerry Wireless thingy while I do other things...

-----Original Message-----
From: Chris Albertson <albertson.chris-***@public.gmane.org>
Sender: time-nuts-bounces-***@public.gmane.org
Date: Thu, 15 Mar 2012 15:48:41
To: Discussion of precise time and frequency measurement<time-nuts-***@public.gmane.org>
Reply-To: Discussion of precise time and frequency measurement
<time-nuts-***@public.gmane.org>
Subject: Re: [time-nuts] WWVB BPSK Receiver Project?

On Thu, Mar 15, 2012 at 3:13 PM, Poul-Henning Kamp <phk-HF+***@public.gmane.org> wrote:
> In message <20120315152620.8347488e049854218aed4aa6-***@public.gmane.org>, Attila Kinali w
> rites:
>
>>> Do you need 16 bits or can you get by with a 12 bit ADC?
>
> In general: The more the merrier, for a digital dude like me, having
> more bits is easier than getting AGC working correctly :-)
>
>>> Have you considered using an FPGA for signal processing? It seems
>> you need a fairly serious CPU to handle that much data.


"That much data" we are talking about 192K samples per second. I can
routinely record multiple tracks of 192K audio and do processing in
real time and the CPU meter hardly moves the bottom. Even a
gigabit per second Ethernet port is not "a lot of data" on a modern
computer.

FPGAs and DSP come into play if you are talking about tens of millions
of samples per second with data rates above say 200Mb/Sec But the
rate from an audio interface running 192K and 24-bits is still under
one megabyte per second. An interesting ratio is the number of CPU
cycles available to process one sample. On my Apple iMac that would
be about roughly 200,000 operations per data sample.

In real life SDR receivers even an older CPU can process the I and Q
channels and maintain a large graphic screen and send and receive data
over a network and still not be "maxed out"


Chris Albertson
Redondo Beach, California

_______________________________________________
time-nuts mailing list -- time-nuts-***@public.gmane.org
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

[Poul-Henning Kamp]

In message <595370411-1332118092-cardhu_decombobulator_blackberry.rim.net-18097
4826--***@public.gmane.org>, shalimr9-***@public.gmane.org writes:

>I was not concerned about processing power on a PC (or Mac for
>that matter) but for the uC that was used in PHK's project.

That was sort of the entire point about the "aducLoran": to show that
for time-nuttery, you don't need much CPU.

If you wanted to extract a real-time modulation of any kind, the situation
is very different, but as long as you just want to extract a carrier
phase/frequency, averaging is the way to go and that is cheap.

--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk-***@public.gmane.org | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

[Jim Lux]

On 3/15/12 6:50 AM, shalimr9-***@public.gmane.org wrote:
> Poul-Henning,
>
> Do you need 16 bits or can you get by with a 12 bit ADC?
>
> Have you considered using an FPGA for signal processing? It seems you need a fairly serious CPU to handle that much data.
>


You could use an FPGA, but the data rate isn't all that high. The
signal is fairly narrow band (<1 kHz, I should think). What you might
want to do is build a ADC/FPGA combo that provides a nice USB/Ethernet
interface for the sample stream which has been digital downconverted and
filtered. the FPGA takes care of the icky glue logic details and does
a bit of decimation.

[Marek Peca]

Dear american colleagues,

as I read last few posts about WWVB, I am very tempted to return to LF
time signal fun. As I wrote you, there vere very good results using cheap
2 IC circuitry and a PC with our local DCF77 signal.

Under influence of this maillist, I am thinking about recreating of the
receiver using recent MCU, ferrite rod on one side, optional 10MHz input,
USB device acting as a standard USB audio class soundcard output.
Everything working with GNUradio, MATLAB, HAM waterfalls etc. out of the
box.

Could be used as an audio frequency front-end for HAM radio, too.

Would you be interested in such a kit? It should be <$100 all inclusive,
if there will be more people involved (let say 5-10) to cover PCBs.


Best regards,
Marek

[Azelio Boriani]

The first move will be to familiarize with this new modulation format. Of
course I can't receive the WWVB but the DCF77 maybe a good test for me.

On Wed, Mar 14, 2012 at 11:08 PM, Brooke Clarke <brooke-***@public.gmane.org> wrote:

> Hi:
>
> I sure would like a WWVB BPSK receiver for the new modulation. The
> processing gains described in the paper John Seamons linked describes
> processing gains that are tens of dB above what's possible with the old AM
> data format. John has also measures the experimental phase modulation
> testing, see: http://www.jks.com/wwvb/wwvb.html
> The WWB paper "New Improved System for WWVB Broadcast" given at the 43rd
> PTTI November 2011 is at: http://jks.com/wwvb.pdf
>
> Part of the processing gain comes directly from the BPSK modulation and
> that amounts to a little over 10 dB improvement, but there's a further 18
> dB gain to be had by accumulating an hours worth of data and processing
> that.
>
> I'm sure in time there will be plenty of low cost ICs designed to receive
> the new signal, but my guess is that many Time Nuts would like to be in on
> the ground floor. Also NIST probably would like to get reports on the new
> signal when they do test transmissions.
>
> How to move forward?
>
> --
> Have Fun,
>
> Brooke Clarke, N6GCE
> http://www.PRC68.com
> http://www.end2partygovernment.com/Brooke4Congress.html
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts-***@public.gmane.org
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>

[Marek Peca]

Dear Time-Nuts,

(new at this list, but reading for long time excellent timekeeping &
oscillator articles)

> I sure would like a WWVB BPSK receiver for the new modulation. (..)
>
> I'm sure in time there will be plenty of low cost ICs designed to receive the
> new signal, but my guess is that many Time Nuts would like to be in on the
> ground floor. Also NIST probably would like to get reports on the new signal
> when they do test transmissions.
>
> How to move forward?

I have no experience with WWVB, since I live in central Europe, but some
time ago I received quite well German DCF77 (77.5kHz) using absolutely
simplistic circuit with no tuned parts except very tolerant ferrite rod
antenna.

The point was direct sampling into an ADC and doing all the business
in a SDR fashion. I wanted to do PRBS PSK tracking and also PLL-less clock
disciplining this way, but there were another priorities, though.

However, if anybody would be interested in, I would be happy to return to
these nice LF circuits.


Greetings from Marek


P.s> A very little bit from DCF77, but only the pre-SDR stage:
http://www.youtube.com/watch?v=Fx9bas49Uow

[J. Forster]

All very nice, but if this change renders all existing receivers useless.
How does that improve things?

All it does is wipe out all the existing phase tracking infrastructure.

The only benefit is to the government who can reuse the WWVB transmitter
and frequency allocation. Everybody else will have to buy new stuff.

Sounds a lot like HDTV fiasco. Making jobs (in China or Korea) by making
scrap.

YMMV,

-John

==============


> Dear Time-Nuts,
>
>
>> I sure would like a WWVB BPSK receiver for the new modulation. (..)
>>
>> I'm sure in time there will be plenty of low cost ICs designed to
>> receive the

[SNIP}

[Brooke Clarke]

Hi John:

They are going to maintain the existing AM modulation format so all the WWVB "Atomic Clocks" will still work. The phase
modulation is added on top of that.

Yes, I expect my HP 117 may no longer work, but I'd much rather have the improved s/n and timing accuracy.

Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/Brooke4Congress.html


J. Forster wrote:
> All very nice, but if this change renders all existing receivers useless.
> How does that improve things?
>
> All it does is wipe out all the existing phase tracking infrastructure.
>
> The only benefit is to the government who can reuse the WWVB transmitter
> and frequency allocation. Everybody else will have to buy new stuff.
>
> Sounds a lot like HDTV fiasco. Making jobs (in China or Korea) by making
> scrap.
>
> YMMV,
>
> -John
>
> ==============
>
>
>> Dear Time-Nuts,
>>
>>
>>> I sure would like a WWVB BPSK receiver for the new modulation. (..)
>>>
>>> I'm sure in time there will be plenty of low cost ICs designed to
>>> receive the
> [SNIP}
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts-***@public.gmane.org
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>

[J. Forster]

Brooke,

As I've said, I don't care about the Time. The time determined by the
start of TV or radio programs is plenty good enough to keep any
appointments.

My only interest is as a standard of Time Interval as a reference for
synthesizers, counters, etc.

If you think about it, unless you are doing something like occultation or
eclipse timing or eBay, the ToD rarely matters.

They killed LORAN, which worked beautifully.

Now it looks like they are going to kill WWVB, which is a bit more
involved, but works.

GPS is not an option without a tall tower.

This is NOT progress, IMO.

-John

==============


> Hi John:
>
> They are going to maintain the existing AM modulation format so all the
> WWVB "Atomic Clocks" will still work. The phase
> modulation is added on top of that.
>
> Yes, I expect my HP 117 may no longer work, but I'd much rather have the
> improved s/n and timing accuracy.
>
> Have Fun,
>
> Brooke Clarke
> http://www.PRC68.com
> http://www.end2partygovernment.com/Brooke4Congress.html
>
>
> J. Forster wrote:
>> All very nice, but if this change renders all existing receivers
>> useless.
>> How does that improve things?
>>
>> All it does is wipe out all the existing phase tracking infrastructure.
>>
>> The only benefit is to the government who can reuse the WWVB transmitter
>> and frequency allocation. Everybody else will have to buy new stuff.
>>
>> Sounds a lot like HDTV fiasco. Making jobs (in China or Korea) by making
>> scrap.
>>
>> YMMV,
>>
>> -John
>>
>> ==============
>>
>>
>>> Dear Time-Nuts,
>>>
>>>
>>>> I sure would like a WWVB BPSK receiver for the new modulation. (..)
>>>>
>>>> I'm sure in time there will be plenty of low cost ICs designed to
>>>> receive the
>> [SNIP}
>>
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts-***@public.gmane.org
>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
>>
>
>

[paul swed]

I am afraid that like John my concern is the frequency reference. Time?
Heck it comes by the internet, WWV or GPS and lastly good old watches that
do pretty well these days. No comments on celphones. So the term is
screwed. All of the sampling and computer processing may indeed loose the
primary reference quality for frequency measurement.
So is all lost?
Well maybe not completely.
Those old receivers are actually pretty nice for filtering the incoming
signal and such. A Singer I have has a good collins 60 Kc filter. So
perhaps as a gain stage they still have value. It gets interesting at the
next step and thats what to do about the reversals of the carrier.
A question I have is this. Since the samples are actually slow on the
comparison. Would a 117 even see it. Is it perhaps just adding additional
filtering. All speculation on my part.
I need to read the dock we have just received more carefully to get a
better understanding.
Happy to run up the fluke 207 and a 117 perhaps on the next set of tests
and see what happens. (207 is actually Johns old unit) Also have a
spectracom 8170. But thats really a clock and as stated should work fine.
Regards
Paul.
WB8TSL

On Wed, Mar 14, 2012 at 8:13 PM, J. Forster <jfor-9KbcMkp5tujQT0dZR+***@public.gmane.org> wrote:

> Brooke,
>
> As I've said, I don't care about the Time. The time determined by the
> start of TV or radio programs is plenty good enough to keep any
> appointments.
>
> My only interest is as a standard of Time Interval as a reference for
> synthesizers, counters, etc.
>
> If you think about it, unless you are doing something like occultation or
> eclipse timing or eBay, the ToD rarely matters.
>
> They killed LORAN, which worked beautifully.
>
> Now it looks like they are going to kill WWVB, which is a bit more
> involved, but works.
>
> GPS is not an option without a tall tower.
>
> This is NOT progress, IMO.
>
> -John
>
> ==============
>
>
> > Hi John:
> >
> > They are going to maintain the existing AM modulation format so all the
> > WWVB "Atomic Clocks" will still work. The phase
> > modulation is added on top of that.
> >
> > Yes, I expect my HP 117 may no longer work, but I'd much rather have the
> > improved s/n and timing accuracy.
> >
> > Have Fun,
> >
> > Brooke Clarke
> > http://www.PRC68.com
> > http://www.end2partygovernment.com/Brooke4Congress.html
> >
> >
> > J. Forster wrote:
> >> All very nice, but if this change renders all existing receivers
> >> useless.
> >> How does that improve things?
> >>
> >> All it does is wipe out all the existing phase tracking infrastructure.
> >>
> >> The only benefit is to the government who can reuse the WWVB transmitter
> >> and frequency allocation. Everybody else will have to buy new stuff.
> >>
> >> Sounds a lot like HDTV fiasco. Making jobs (in China or Korea) by making
> >> scrap.
> >>
> >> YMMV,
> >>
> >> -John
> >>
> >> ==============
> >>
> >>
> >>> Dear Time-Nuts,
> >>>
> >>>
> >>>> I sure would like a WWVB BPSK receiver for the new modulation. (..)
> >>>>
> >>>> I'm sure in time there will be plenty of low cost ICs designed to
> >>>> receive the
> >> [SNIP}
> >>
> >>
> >> _______________________________________________
> >> time-nuts mailing list -- time-nuts-***@public.gmane.org
> >> To unsubscribe, go to
> >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> >> and follow the instructions there.
> >>
> >>
> >
> >
>
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts-***@public.gmane.org
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>

[David I. Emery]

On Wed, Mar 14, 2012 at 05:13:47PM -0700, J. Forster wrote:
> Now it looks like they are going to kill WWVB, which is a bit more
> involved, but works.
>
> GPS is not an option without a tall tower.

Everything you say up to this makes perfect sense, but what makes
you think GPS timing fails to work with less than a tall tower ?

I believe it is readily possible to get to the 10-30 ns of
UTC/TAI TOD area with just reasonable sky view, not 100% as implied by a
tower. And certainly 1E-11 or 1E-12 frequency accuracy is also readily
available with less than perfect sky view depending on your taus...

Perhaps ultimate performance requires really unobstructed sky view
in order to absolutely minimize multipath but then you are probably
talking 1E-13 or better...


> This is NOT progress, IMO.

Virtually ANY GPS timing solution ought to easily get you inside of
a couple of microseconds of UTC/TAI, I am pretty sure it is quite difficult
to get within 10-100 us with the current AM modulation of WWVB, possibly
even 1-10 ms is difficult. And anything close to this requires accurate
knowledge of geographic position and 60 KHz propagation corrections.

I'm not clear how accurately one can resolve the phase transition
in the new scheme, but I suspect probably unambiguously to 1 cycle of
the 60 KHz... and from there is merely a function of how accurately one
can resolve the phase of the 60 KHz. This potentially can supply a
much higher resolution time hack than the AM envelope.

The real question being how important is preserving backward
compatibility with antique equipment versus better performance...

I agree that ALWAYS is a trade off...


>
> -John
>
> ==============
>
>
> > Hi John:
> >
> > They are going to maintain the existing AM modulation format so all the
> > WWVB "Atomic Clocks" will still work. The phase
> > modulation is added on top of that.
> >
> > Yes, I expect my HP 117 may no longer work, but I'd much rather have the
> > improved s/n and timing accuracy.
> >
> > Have Fun,
> >
> > Brooke Clarke
> > http://www.PRC68.com
> > http://www.end2partygovernment.com/Brooke4Congress.html
> >
> >
> > J. Forster wrote:
> >> All very nice, but if this change renders all existing receivers
> >> useless.
> >> How does that improve things?
> >>
> >> All it does is wipe out all the existing phase tracking infrastructure.
> >>
> >> The only benefit is to the government who can reuse the WWVB transmitter
> >> and frequency allocation. Everybody else will have to buy new stuff.
> >>
> >> Sounds a lot like HDTV fiasco. Making jobs (in China or Korea) by making
> >> scrap.
> >>
> >> YMMV,
> >>
> >> -John
> >>
> >> ==============
> >>
> >>
> >>> Dear Time-Nuts,
> >>>
> >>>
> >>>> I sure would like a WWVB BPSK receiver for the new modulation. (..)
> >>>>
> >>>> I'm sure in time there will be plenty of low cost ICs designed to
> >>>> receive the
> >> [SNIP}
> >>
> >>
> >> _______________________________________________
> >> time-nuts mailing list -- time-nuts-***@public.gmane.org
> >> To unsubscribe, go to
> >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> >> and follow the instructions there.
> >>
> >>
> >
> >
>
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts-***@public.gmane.org
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

--
Dave Emery N1PRE/AE, die-NI3WtVA4WvYg9ELcbhaJlAC/***@public.gmane.org DIE Consulting, Weston, Mass 02493
"An empty zombie mind with a forlorn barely readable weatherbeaten
'For Rent' sign still vainly flapping outside on the weed encrusted pole - in
celebration of what could have been, but wasn't and is not to be now either."

[paul swed]

John
Like your thought. I seem to remember costas loops work like that to
recover the carrier.
Had seen it in amsat many years ago. So perhaps an approach is to limit if
possible the incoming signal.
Though further simple dumb thought. A NE602 or SA602 or also teh 612
series. All the same mixer circuit (Or multiplier)will double the incoming
frequency if you delay the incoming by 90 degrees I think. Its a sensitive
chip and has a 17 db conversion gain and is $2.40 at digikey. 8 pin dip.
though what ever the delay at 60KC thats a long delay. ;-)
Regards
Paul

On Wed, Mar 14, 2012 at 10:12 PM, David I. Emery <die-NI3WtVA4WvYg9ELcbhaJlAC/***@public.gmane.org>wrote:

> On Wed, Mar 14, 2012 at 05:13:47PM -0700, J. Forster wrote:
> > Now it looks like they are going to kill WWVB, which is a bit more
> > involved, but works.
> >
> > GPS is not an option without a tall tower.
>
> Everything you say up to this makes perfect sense, but what makes
> you think GPS timing fails to work with less than a tall tower ?
>
> I believe it is readily possible to get to the 10-30 ns of
> UTC/TAI TOD area with just reasonable sky view, not 100% as implied by a
> tower. And certainly 1E-11 or 1E-12 frequency accuracy is also readily
> available with less than perfect sky view depending on your taus...
>
> Perhaps ultimate performance requires really unobstructed sky view
> in order to absolutely minimize multipath but then you are probably
> talking 1E-13 or better...
>
>
> > This is NOT progress, IMO.
>
> Virtually ANY GPS timing solution ought to easily get you inside of
> a couple of microseconds of UTC/TAI, I am pretty sure it is quite difficult
> to get within 10-100 us with the current AM modulation of WWVB, possibly
> even 1-10 ms is difficult. And anything close to this requires accurate
> knowledge of geographic position and 60 KHz propagation corrections.
>
> I'm not clear how accurately one can resolve the phase transition
> in the new scheme, but I suspect probably unambiguously to 1 cycle of
> the 60 KHz... and from there is merely a function of how accurately one
> can resolve the phase of the 60 KHz. This potentially can supply a
> much higher resolution time hack than the AM envelope.
>
> The real question being how important is preserving backward
> compatibility with antique equipment versus better performance...
>
> I agree that ALWAYS is a trade off...
>
>
> >
> > -John
> >
> > ==============
> >
> >
> > > Hi John:
> > >
> > > They are going to maintain the existing AM modulation format so all the
> > > WWVB "Atomic Clocks" will still work. The phase
> > > modulation is added on top of that.
> > >
> > > Yes, I expect my HP 117 may no longer work, but I'd much rather have
> the
> > > improved s/n and timing accuracy.
> > >
> > > Have Fun,
> > >
> > > Brooke Clarke
> > > http://www.PRC68.com
> > > http://www.end2partygovernment.com/Brooke4Congress.html
> > >
> > >
> > > J. Forster wrote:
> > >> All very nice, but if this change renders all existing receivers
> > >> useless.
> > >> How does that improve things?
> > >>
> > >> All it does is wipe out all the existing phase tracking
> infrastructure.
> > >>
> > >> The only benefit is to the government who can reuse the WWVB
> transmitter
> > >> and frequency allocation. Everybody else will have to buy new stuff.
> > >>
> > >> Sounds a lot like HDTV fiasco. Making jobs (in China or Korea) by
> making
> > >> scrap.
> > >>
> > >> YMMV,
> > >>
> > >> -John
> > >>
> > >> ==============
> > >>
> > >>
> > >>> Dear Time-Nuts,
> > >>>
> > >>>
> > >>>> I sure would like a WWVB BPSK receiver for the new modulation. (..)
> > >>>>
> > >>>> I'm sure in time there will be plenty of low cost ICs designed to
> > >>>> receive the
> > >> [SNIP}
> > >>
> > >>
> > >> _______________________________________________
> > >> time-nuts mailing list -- time-nuts-***@public.gmane.org
> > >> To unsubscribe, go to
> > >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > >> and follow the instructions there.
> > >>
> > >>
> > >
> > >
> >
> >
> >
> > _______________________________________________
> > time-nuts mailing list -- time-nuts-***@public.gmane.org
> > To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
>
> --
> Dave Emery N1PRE/AE, die-NI3WtVA4WvYg9ELcbhaJlAC/***@public.gmane.org DIE Consulting, Weston, Mass
> 02493
> "An empty zombie mind with a forlorn barely readable weatherbeaten
> 'For Rent' sign still vainly flapping outside on the weed encrusted pole -
> in
> celebration of what could have been, but wasn't and is not to be now
> either."
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts-***@public.gmane.org
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>

[J. Forster]

> John
> Like your thought. I seem to remember costas loops work like that to
> recover the carrier.

Paul,

It recovers a bipolar signal to steer the local VCO as well as the data..
It also needs a quadratue hybrid at the VCO frequency (although it might
be fairly easy to make a quadrature oscillator vat 60 kHz.)

> Had seen it in amsat many years ago. So perhaps an approach is to limit
> if possible the incoming signal.

I'm not sure if it works properly with clipped (digital) dignals, off hand.

> Though further simple dumb thought. A NE602 or SA602 or also teh 612
> series. All the same mixer circuit (Or multiplier)will double the incoming
> frequency if you delay the incoming by 90 degrees I think.

Sine and Cosine are orthogonal. You need to do (Sine)*(Sine)

sin^2 (wt) = 1/2(1 - cos (2wt)

>Its a sensitive chip and has a 17 db conversion gain and is $2.40 at
> digikey. 8 pin dip. though what ever the delay at 60KC thats a long
delay. ;-)

The delay (phase shift) is not needed.

Best,

-John

=============


> Regards
> Paul
>
> On Wed, Mar 14, 2012 at 10:12 PM, David I. Emery
> <die-NI3WtVA4WvYg9ELcbhaJlAC/***@public.gmane.org>wrote:
>
>> On Wed, Mar 14, 2012 at 05:13:47PM -0700, J. Forster wrote:
>> > Now it looks like they are going to kill WWVB, which is a bit more
>> > involved, but works.
>> >
>> > GPS is not an option without a tall tower.
>>
>> Everything you say up to this makes perfect sense, but what
>> makes
>> you think GPS timing fails to work with less than a tall tower ?
>>
>> I believe it is readily possible to get to the 10-30 ns of
>> UTC/TAI TOD area with just reasonable sky view, not 100% as implied by a
>> tower. And certainly 1E-11 or 1E-12 frequency accuracy is also readily
>> available with less than perfect sky view depending on your taus...
>>
>> Perhaps ultimate performance requires really unobstructed sky
>> view
>> in order to absolutely minimize multipath but then you are probably
>> talking 1E-13 or better...
>>
>>
>> > This is NOT progress, IMO.
>>
>> Virtually ANY GPS timing solution ought to easily get you inside
>> of
>> a couple of microseconds of UTC/TAI, I am pretty sure it is quite
>> difficult
>> to get within 10-100 us with the current AM modulation of WWVB, possibly
>> even 1-10 ms is difficult. And anything close to this requires
>> accurate
>> knowledge of geographic position and 60 KHz propagation corrections.
>>
>> I'm not clear how accurately one can resolve the phase transition
>> in the new scheme, but I suspect probably unambiguously to 1 cycle of
>> the 60 KHz... and from there is merely a function of how accurately one
>> can resolve the phase of the 60 KHz. This potentially can supply a
>> much higher resolution time hack than the AM envelope.
>>
>> The real question being how important is preserving backward
>> compatibility with antique equipment versus better performance...
>>
>> I agree that ALWAYS is a trade off...
>>
>>
>> >
>> > -John
>> >
>> > ==============
>> >
>> >
>> > > Hi John:
>> > >
>> > > They are going to maintain the existing AM modulation format so all
>> the
>> > > WWVB "Atomic Clocks" will still work. The phase
>> > > modulation is added on top of that.
>> > >
>> > > Yes, I expect my HP 117 may no longer work, but I'd much rather have
>> the
>> > > improved s/n and timing accuracy.
>> > >
>> > > Have Fun,
>> > >
>> > > Brooke Clarke
>> > > http://www.PRC68.com
>> > > http://www.end2partygovernment.com/Brooke4Congress.html
>> > >
>> > >
>> > > J. Forster wrote:
>> > >> All very nice, but if this change renders all existing receivers
>> > >> useless.
>> > >> How does that improve things?
>> > >>
>> > >> All it does is wipe out all the existing phase tracking
>> infrastructure.
>> > >>
>> > >> The only benefit is to the government who can reuse the WWVB
>> transmitter
>> > >> and frequency allocation. Everybody else will have to buy new
>> stuff.
>> > >>
>> > >> Sounds a lot like HDTV fiasco. Making jobs (in China or Korea) by
>> making
>> > >> scrap.
>> > >>
>> > >> YMMV,
>> > >>
>> > >> -John
>> > >>
>> > >> ==============
>> > >>
>> > >>
>> > >>> Dear Time-Nuts,
>> > >>>
>> > >>>
>> > >>>> I sure would like a WWVB BPSK receiver for the new modulation.
>> (..)
>> > >>>>
>> > >>>> I'm sure in time there will be plenty of low cost ICs designed to
>> > >>>> receive the
>> > >> [SNIP}
>> > >>
>> > >>
>> > >> _______________________________________________
>> > >> time-nuts mailing list -- time-nuts-***@public.gmane.org
>> > >> To unsubscribe, go to
>> > >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> > >> and follow the instructions there.
>> > >>
>> > >>
>> > >
>> > >
>> >
>> >
>> >
>> > _______________________________________________
>> > time-nuts mailing list -- time-nuts-***@public.gmane.org
>> > To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> > and follow the instructions there.
>>
>> --
>> Dave Emery N1PRE/AE, die-NI3WtVA4WvYg9ELcbhaJlAC/***@public.gmane.org DIE Consulting, Weston,
>> Mass
>> 02493
>> "An empty zombie mind with a forlorn barely readable weatherbeaten
>> 'For Rent' sign still vainly flapping outside on the weed encrusted pole
>> -
>> in
>> celebration of what could have been, but wasn't and is not to be now
>> either."
>>
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts-***@public.gmane.org
>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
> _______________________________________________
> time-nuts mailing list -- time-nuts-***@public.gmane.org
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>

[Jim Lux]

On 3/14/12 8:07 PM, J. Forster wrote:
>> John
>> Like your thought. I seem to remember costas loops work like that to
>> recover the carrier.
>
> Paul,
>
> It recovers a bipolar signal to steer the local VCO as well as the data..
> It also needs a quadratue hybrid at the VCO frequency (although it might
> be fairly easy to make a quadrature oscillator vat 60 kHz.)

One easy scheme is to make your VCO run at a multiple and divide down to
generate the two quadrature square waves.

>
>> Had seen it in amsat many years ago. So perhaps an approach is to limit
>> if possible the incoming signal.
>
> I'm not sure if it works properly with clipped (digital) dignals, off hand.

Yes it will.

>
>> Though further simple dumb thought. A NE602 or SA602 or also teh 612
>> series. All the same mixer circuit (Or multiplier)will double the incoming
>> frequency if you delay the incoming by 90 degrees I think.
>
> Sine and Cosine are orthogonal. You need to do (Sine)*(Sine)
>
> sin^2 (wt) = 1/2(1 - cos (2wt)
>

This is like the classic squaring technique to receive PN coded signals
without knowing the code. (it's used in some "codeless" GPS receivers..
you can retrieve frequency and phase)

[J. Forster]

> On 3/14/12 8:07 PM, J. Forster wrote:
>>> John
>>> Like your thought. I seem to remember costas loops work like that to
>>> recover the carrier.
>>
>> Paul,
>>
>> It recovers a bipolar signal to steer the local VCO as well as the
>> data..
>> It also needs a quadratue hybrid at the VCO frequency (although it might
>> be fairly easy to make a quadrature oscillator vat 60 kHz.)
>
> One easy scheme is to make your VCO run at a multiple and divide down to
> generate the two quadrature square waves.

Doesn't look like that works with the HP 117A. I don't know about other
receivers.

>>> Had seen it in amsat many years ago. So perhaps an approach is to limit
>>> if possible the incoming signal.
>>
>> I'm not sure if it works properly with clipped (digital) dignals, off
>> hand.
>
> Yes it will.

Not w/o a quadrature drive to the mixer/multiplier. A square wave,
multiplied by itself, has the same output as input.

>>> Though further simple dumb thought. A NE602 or SA602 or also teh 612
>>> series. All the same mixer circuit (Or multiplier)will double the
>>> incoming
>>> frequency if you delay the incoming by 90 degrees I think.
>>
>> Sine and Cosine are orthogonal. You need to do (Sine)*(Sine)
>>
>> sin^2 (wt) = 1/2(1 - cos (2wt)
>>
>
> This is like the classic squaring technique to receive PN coded signals
> without knowing the code. (it's used in some "codeless" GPS receivers..
> you can retrieve frequency and phase)

A Costas Loop recovers the bit stream and the carrier frequency (from the
local VCO) from a BPSK. It is self syncronizing.

I'm beginning to think that, for the HP 117A at least, a fix could be
built on a small daughter board.

Also, I think that NIST should do the engineering and maybe run the boards
too.

-John

===============

[Jim Lux]

On 3/14/12 9:14 PM, J. Forster wrote:
>> On 3/14/12 8:07 PM, J. Forster wrote:
>>>> John
>>>> Like your thought. I seem to remember costas loops work like that to
>>>> recover the carrier.
>>>
>>> Paul,
>>>
>>> It recovers a bipolar signal to steer the local VCO as well as the
>>> data..
>>> It also needs a quadratue hybrid at the VCO frequency (although it might
>>> be fairly easy to make a quadrature oscillator vat 60 kHz.)
>>
>> One easy scheme is to make your VCO run at a multiple and divide down to
>> generate the two quadrature square waves.
>
> Doesn't look like that works with the HP 117A. I don't know about other
> receivers.
>
>>>> Had seen it in amsat many years ago. So perhaps an approach is to limit
>>>> if possible the incoming signal.
>>>
>>> I'm not sure if it works properly with clipped (digital) dignals, off
>>> hand.
>>
>> Yes it will.
>
> Not w/o a quadrature drive to the mixer/multiplier. A square wave,
> multiplied by itself, has the same output as input.

Oh... I was assuming you had the two quadrature square waves (which are
just like the saturated LO for the mixer in RF land)



>
>>>> Though further simple dumb thought. A NE602 or SA602 or also teh 612
>>>> series. All the same mixer circuit (Or multiplier)will double the
>>>> incoming
>>>> frequency if you delay the incoming by 90 degrees I think.
>>>
>>> Sine and Cosine are orthogonal. You need to do (Sine)*(Sine)
>>>
>>> sin^2 (wt) = 1/2(1 - cos (2wt)
>>>
>>
>> This is like the classic squaring technique to receive PN coded signals
>> without knowing the code. (it's used in some "codeless" GPS receivers..
>> you can retrieve frequency and phase)
>
> A Costas Loop recovers the bit stream and the carrier frequency (from the
> local VCO) from a BPSK. It is self syncronizing.


Yes.. but if you don't care about the bitstream, and you want simpler
hardware, squaring works. (especially if the modulator doesn't have good
carrier suppression)

[J. Forster]

Jim wrote:

a square wave,
>> multiplied by itself, has the same output as input.
>
> Oh... I was assuming you had the two quadrature square waves (which are
> just like the saturated LO for the mixer in RF land)

You don't have two square waves in quadrature. You have the (amplified)
signal from the antenna.


>> A Costas Loop recovers the bit stream and the carrier frequency (from
>> the local VCO) from a BPSK. It is self syncronizing.
>
>
> Yes.. but if you don't care about the bitstream, and you want simpler
> hardware, squaring works. (especially if the modulator doesn't have good
> carrier suppression)

I think a better implementation would be:

Analog multiplier
Adaptive comparator (slice level = 1/2 P_P signal)
Flip Flop
Rabbit ears filter at 60 kHz

-John

=============

>
> _______________________________________________
> time-nuts mailing list -- time-nuts-***@public.gmane.org
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>

[Peter Monta]

>        I'm not clear how accurately one can resolve the phase transition
> in the new scheme, but I suspect probably unambiguously to 1 cycle of
> the 60 KHz... and from there is merely a function of how accurately one
> can resolve the phase of the 60 KHz.    This potentially can supply a
> much higher resolution time hack than the AM envelope.

I think the low transmitting-antenna bandwidth will prevent an
unambiguous identification of the exact cycle of phase inversion, just
as it smears out the AM transition from high power to low power.
Fitting a model to the signal's AM exponential decay (or PM
transition) would be better than a simple threshold, but at best it
might get down to 50 us territory (excluding the propagation delay and
iono uncertainties).

Cheers,
Peter

[WB6BNQ]

Brooke,

In speaking with John Lowe of NIST (Group Leader for Time & Frequency service), he stated that the absolute time recovery of
their intended new modulation scheme is 10 milliseconds. Nothing stellar there !

BUT you are right, all of us that have hp-117 type receivers are just out of luck. John Lowe did say they are going to
produce a PIC (Microchip) project that will grab the data stream and reconstruct the carrier signal so that can then be fed
back into a hp-117 type receiver so it can still be used. However, he did say that is a dream at the moment as they have
not really started to work on it. He then said I could do it and they would consider my efforts. While I had a number of
thoughts running though mind when he said that; I did hold my comments back.

I have to tell you, John Lowe sounded like he was drinking the Kool-Aid because I told him I was quite negative to the whole
idea and he went into a nonstop mode of telling me all the good things that were going to come about with this modulation
scheme. The same kind of hype that occurred with the HDTV. By the way, all those good things have nothing to do with
anything Time-nutty except for pissing us off, as it were.

His enthusiasm was aimed totally at new products. Although he admitted it leaves all the real Timenut type people, actually
using the system for its intended purpose, out in the cold, he really did not seem to care. Pointing out that a failure
with the GPS system left WWVB as the only alternate did not seem to matter either.

OH Well,

Bill....WB6BNQ


Brooke Clarke wrote:

> Hi John:
>
> They are going to maintain the existing AM modulation format so all the WWVB "Atomic Clocks" will still work. The phase
> modulation is added on top of that.
>
> Yes, I expect my HP 117 may no longer work, but I'd much rather have the improved s/n and timing accuracy.
>
> Have Fun,
>
> Brooke Clarke
> http://www.PRC68.com
> http://www.end2partygovernment.com/Brooke4Congress.html
>
> J. Forster wrote:
> > All very nice, but if this change renders all existing receivers useless.
> > How does that improve things?
> >
> > All it does is wipe out all the existing phase tracking infrastructure.
> >
> > The only benefit is to the government who can reuse the WWVB transmitter
> > and frequency allocation. Everybody else will have to buy new stuff.
> >
> > Sounds a lot like HDTV fiasco. Making jobs (in China or Korea) by making
> > scrap.
> >
> > YMMV,
> >
> > -John
> >
> > ==============
> >
> >
> >> Dear Time-Nuts,
> >>
> >>
> >>> I sure would like a WWVB BPSK receiver for the new modulation. (..)
> >>>
> >>> I'm sure in time there will be plenty of low cost ICs designed to
> >>> receive the
> > [SNIP}
> >
> >
> > _______________________________________________
> > time-nuts mailing list -- time-nuts-***@public.gmane.org
> > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
> >
> >
>
> _______________________________________________
> time-nuts mailing list -- time-nuts-***@public.gmane.org
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

[paul swed]

OK thats great a maybe pic chip answer. They do cure all ill's after all.
Really scratching my head here. But I do think there is an answer as long
as the phase reversal is accurately controlled and still referenced to the
reference standard.
A I say I need to read.
Regards
Paul

On Wed, Mar 14, 2012 at 9:14 PM, WB6BNQ <wb6bnq-***@public.gmane.org> wrote:

> Brooke,
>
> In speaking with John Lowe of NIST (Group Leader for Time & Frequency
> service), he stated that the absolute time recovery of
> their intended new modulation scheme is 10 milliseconds. Nothing stellar
> there !
>
> BUT you are right, all of us that have hp-117 type receivers are just out
> of luck. John Lowe did say they are going to
> produce a PIC (Microchip) project that will grab the data stream and
> reconstruct the carrier signal so that can then be fed
> back into a hp-117 type receiver so it can still be used. However, he did
> say that is a dream at the moment as they have
> not really started to work on it. He then said I could do it and they
> would consider my efforts. While I had a number of
> thoughts running though mind when he said that; I did hold my comments
> back.
>
> I have to tell you, John Lowe sounded like he was drinking the Kool-Aid
> because I told him I was quite negative to the whole
> idea and he went into a nonstop mode of telling me all the good things
> that were going to come about with this modulation
> scheme. The same kind of hype that occurred with the HDTV. By the way,
> all those good things have nothing to do with
> anything Time-nutty except for pissing us off, as it were.
>
> His enthusiasm was aimed totally at new products. Although he admitted it
> leaves all the real Timenut type people, actually
> using the system for its intended purpose, out in the cold, he really did
> not seem to care. Pointing out that a failure
> with the GPS system left WWVB as the only alternate did not seem to matter
> either.
>
> OH Well,
>
> Bill....WB6BNQ
>
>
> Brooke Clarke wrote:
>
> > Hi John:
> >
> > They are going to maintain the existing AM modulation format so all the
> WWVB "Atomic Clocks" will still work. The phase
> > modulation is added on top of that.
> >
> > Yes, I expect my HP 117 may no longer work, but I'd much rather have the
> improved s/n and timing accuracy.
> >
> > Have Fun,
> >
> > Brooke Clarke
> > http://www.PRC68.com
> > http://www.end2partygovernment.com/Brooke4Congress.html
> >
> > J. Forster wrote:
> > > All very nice, but if this change renders all existing receivers
> useless.
> > > How does that improve things?
> > >
> > > All it does is wipe out all the existing phase tracking infrastructure.
> > >
> > > The only benefit is to the government who can reuse the WWVB
> transmitter
> > > and frequency allocation. Everybody else will have to buy new stuff.
> > >
> > > Sounds a lot like HDTV fiasco. Making jobs (in China or Korea) by
> making
> > > scrap.
> > >
> > > YMMV,
> > >
> > > -John
> > >
> > > ==============
> > >
> > >
> > >> Dear Time-Nuts,
> > >>
> > >>
> > >>> I sure would like a WWVB BPSK receiver for the new modulation. (..)
> > >>>
> > >>> I'm sure in time there will be plenty of low cost ICs designed to
> > >>> receive the
> > > [SNIP}
> > >
> > >
> > > _______________________________________________
> > > time-nuts mailing list -- time-nuts-***@public.gmane.org
> > > To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > > and follow the instructions there.
> > >
> > >
> >
> > _______________________________________________
> > time-nuts mailing list -- time-nuts-***@public.gmane.org
> > To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts-***@public.gmane.org
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>

[J. Forster]

In thinking about it a bit further, one might be able to take the 60 kHz
received sine at some point in the receiver, full wave rectify and HP
filter it (which doubles the frequency) then divide by two in a Flip-Flop
and heavily filter the resultant. This is a hybrid solution... analog and
digital... with not a uP in sight!!

That would preserve the frequency, but ditch the phase reversals of the
BPSK. Depending on the guts of the particular receiver, it might be
possible to simply retrofit a PCB.

The 180 degree phase reversal of the BPSK is just about the worst possible
thing for a PLL of typical receicers. If the ratio of 1s to 0s is 50% the
loop just thrashes.

-John

================




> OK thats great a maybe pic chip answer. They do cure all ill's after all.
> Really scratching my head here. But I do think there is an answer as long
> as the phase reversal is accurately controlled and still referenced to the
> reference standard.
> A I say I need to read.
> Regards
> Paul
>
> On Wed, Mar 14, 2012 at 9:14 PM, WB6BNQ <wb6bnq-***@public.gmane.org> wrote:
>
>> Brooke,
>>
>> In speaking with John Lowe of NIST (Group Leader for Time & Frequency
>> service), he stated that the absolute time recovery of
>> their intended new modulation scheme is 10 milliseconds. Nothing
>> stellar
>> there !
>>
>> BUT you are right, all of us that have hp-117 type receivers are just
>> out
>> of luck. John Lowe did say they are going to
>> produce a PIC (Microchip) project that will grab the data stream and
>> reconstruct the carrier signal so that can then be fed
>> back into a hp-117 type receiver so it can still be used. However, he
>> did
>> say that is a dream at the moment as they have
>> not really started to work on it. He then said I could do it and they
>> would consider my efforts. While I had a number of
>> thoughts running though mind when he said that; I did hold my comments
>> back.
>>
>> I have to tell you, John Lowe sounded like he was drinking the Kool-Aid
>> because I told him I was quite negative to the whole
>> idea and he went into a nonstop mode of telling me all the good things
>> that were going to come about with this modulation
>> scheme. The same kind of hype that occurred with the HDTV. By the way,
>> all those good things have nothing to do with
>> anything Time-nutty except for pissing us off, as it were.
>>
>> His enthusiasm was aimed totally at new products. Although he admitted
>> it
>> leaves all the real Timenut type people, actually
>> using the system for its intended purpose, out in the cold, he really
>> did
>> not seem to care. Pointing out that a failure
>> with the GPS system left WWVB as the only alternate did not seem to
>> matter
>> either.
>>
>> OH Well,
>>
>> Bill....WB6BNQ
>>
>>
>> Brooke Clarke wrote:
>>
>> > Hi John:
>> >
>> > They are going to maintain the existing AM modulation format so all
>> the
>> WWVB "Atomic Clocks" will still work. The phase
>> > modulation is added on top of that.
>> >
>> > Yes, I expect my HP 117 may no longer work, but I'd much rather have
>> the
>> improved s/n and timing accuracy.
>> >
>> > Have Fun,
>> >
>> > Brooke Clarke
>> > http://www.PRC68.com
>> > http://www.end2partygovernment.com/Brooke4Congress.html
>> >
>> > J. Forster wrote:
>> > > All very nice, but if this change renders all existing receivers
>> useless.
>> > > How does that improve things?
>> > >
>> > > All it does is wipe out all the existing phase tracking
>> infrastructure.
>> > >
>> > > The only benefit is to the government who can reuse the WWVB
>> transmitter
>> > > and frequency allocation. Everybody else will have to buy new stuff.
>> > >
>> > > Sounds a lot like HDTV fiasco. Making jobs (in China or Korea) by
>> making
>> > > scrap.
>> > >
>> > > YMMV,
>> > >
>> > > -John
>> > >
>> > > ==============
>> > >
>> > >
>> > >> Dear Time-Nuts,
>> > >>
>> > >>
>> > >>> I sure would like a WWVB BPSK receiver for the new modulation.
>> (..)
>> > >>>
>> > >>> I'm sure in time there will be plenty of low cost ICs designed to
>> > >>> receive the
>> > > [SNIP}
>> > >
>> > >
>> > > _______________________________________________
>> > > time-nuts mailing list -- time-nuts-***@public.gmane.org
>> > > To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> > > and follow the instructions there.
>> > >
>> > >
>> >
>> > _______________________________________________
>> > time-nuts mailing list -- time-nuts-***@public.gmane.org
>> > To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> > and follow the instructions there.
>>
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts-***@public.gmane.org
>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
> _______________________________________________
> time-nuts mailing list -- time-nuts-***@public.gmane.org
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>

[Peter Monta]

> In thinking about it a bit further, one might be able to take the 60 kHz
> received sine at some point in the receiver, full wave rectify and HP
> filter it (which doubles the frequency) then divide by two in a Flip-Flop
> and heavily filter the resultant. This is a hybrid solution... analog and
> digital...  with not a uP in sight!!
>
> That would preserve the frequency, but ditch the phase reversals of the
> BPSK. Depending on the guts of the particular receiver, it might be
> possible to simply retrofit a PCB.

There would be an SNR penalty for this, though, called "squaring
loss". A PIC that knew when the transitions would happen and inverted
the original signal would be free of squaring loss, since its
reversing-signal would be noiseless.

My worry, though, is that even this preprocessing doesn't look like it
would give as good a signal as the original WWVB. Eyeballing the
phase data derived from John Seamons' capture seems to show some phase
variation from bit to bit, even those bits with the same nominal
carrier phase. Some nonlinearity in the transmitter when hit with
these phase transients perhaps. How quickly does it average out in a
carrier-phase receiver? Unknown.

Cheers,
Peter

[Charles P. Steinmetz]

Bill wrote:

>[BPSK] leaves all the real Timenut type people, actually
>using the system for its intended purpose, out in the cold

To be fair to NIST, there really aren't many people using WWVB as a
source of laboratory-grade timing signals. As others have pointed
out, it isn't accurate enough for true time nut performance, and to
get all of what it *is* capable of requires heroic efforts. So in
truth, the real market for WWVB is not time nuts -- it is people who
want to know the time of day to within a second (the "atomic" clock
crowd). And there are LOTS of them. So the change is likely to
provide a modest upgrade path for the vast majority of actual users,
at the expense of a few die-hards (hobbyists, mostly) who are trying
to get more out of an LF timing source than it is really capable of
delivering.

From a public policy standpoint it seems to make good sense, however
much it may offend time nuts' sensibilities.

Best regards,

Charles

[Poul-Henning Kamp]

In message <20120315043646.1BC3F11BB72-/XpyNRDPLAPf/iOm8unkrwC/***@public.gmane.org>, "Charles P. Steinmet
z" writes:

>As others have pointed
>out, it isn't accurate enough for true time nut performance, and to
>get all of what it *is* capable of requires heroic efforts.

And isn't that what being a time-nut is all about ?

VLF signals, once they have phase-code, are pretty good for frequency
stabilization, you just need to use an averaging time of 24 hours.

--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk-***@public.gmane.org | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

[Brooke Clarke]

Hi Charles:

There's another thing the WWVB (& WWV) do that GPS does not and that's Daylight Saving Time.
Pop quiz. . . . what are the dates DST is turned on and off?
http://en.wikipedia.org/wiki/Daylight_saving_time_around_the_world#United_States_of_America

Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/Brooke4Congress.html


Charles P. Steinmetz wrote:
> Bill wrote:
>
>> [BPSK] leaves all the real Timenut type people, actually
>> using the system for its intended purpose, out in the cold
>
> To be fair to NIST, there really aren't many people using WWVB as a source of laboratory-grade timing signals. As
> others have pointed out, it isn't accurate enough for true time nut performance, and to get all of what it *is*
> capable of requires heroic efforts. So in truth, the real market for WWVB is not time nuts -- it is people who want
> to know the time of day to within a second (the "atomic" clock crowd). And there are LOTS of them. So the change is
> likely to provide a modest upgrade path for the vast majority of actual users, at the expense of a few die-hards
> (hobbyists, mostly) who are trying to get more out of an LF timing source than it is really capable of delivering.
>
> From a public policy standpoint it seems to make good sense, however much it may offend time nuts' sensibilities.
>
> Best regards,
>
> Charles
>
>
>
>
>
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts-***@public.gmane.org
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>

[Charles P. Steinmetz]

Brooke wrote:

>There's another thing the WWVB (& WWV) do that GPS does not and
>that's Daylight Saving Time.

Doesn't that reinforce my point? Automatic adjustment of time-of-day
clocks for DST is not really a time nut priority, is it? Very
convenient in daily life, yes -- but to the general public, time nuts
included, not to time nuts qua time nuts.

Best regards,

Charles

[Attila Kinali]

On Wed, 14 Mar 2012 18:14:56 -0700
WB6BNQ <wb6bnq-***@public.gmane.org> wrote:

>
> His enthusiasm was aimed totally at new products. Although he admitted
> it leaves all the real Timenut type people, actually
> using the system for its intended purpose, out in the cold, he really
> did not seem to care. Pointing out that a failure
> with the GPS system left WWVB as the only alternate did not seem to
> matter either.

Could someone be so kind and could explain me what the problem with
the BPSK modulation is? I mean the phase of WWVB shifts around several 10us
during sunrise/sunset already... Not to talk about the changing propagation
conditions. Just see [1] for an example of what's happening.

Yes, for those devices that lock on the phase, you'd have to change
their correction/detection loop, but overall, they should still work.


Attila Kinali


[1] http://www.febo.com/time-freq/wwvb/spectracom/index.html

--
The trouble with you, Shev, is you don't say anything until you've saved
up a whole truckload of damned heavy brick arguments and then you dump
them all out and never look at the bleeding body mangled beneath the heap
-- Tirin, The Dispossessed, U. Le Guin

[J. Forster]

Suppose the modulation is not present. The output of the phase detector
that steers the local standard ot indicator works correctly.

Now reverse the 60 kHz carrier. The phase detector works exactly thye
opposite way... wrong.

Now alternate between 0 and 190 degrees.

The loop alternate works between exactly right and exactly wrong... it
dithers around and the output is a measure of the ratio of 1's to 0's and
is utterly useless.

-John

============


> On Wed, 14 Mar 2012 18:14:56 -0700
> WB6BNQ <wb6bnq-***@public.gmane.org> wrote:
>
>>
>> His enthusiasm was aimed totally at new products. Although he admitted
>> it leaves all the real Timenut type people, actually
>> using the system for its intended purpose, out in the cold, he really
>> did not seem to care. Pointing out that a failure
>> with the GPS system left WWVB as the only alternate did not seem to
>> matter either.
>
> Could someone be so kind and could explain me what the problem with
> the BPSK modulation is? I mean the phase of WWVB shifts around several
> 10us
> during sunrise/sunset already... Not to talk about the changing
> propagation
> conditions. Just see [1] for an example of what's happening.
>
> Yes, for those devices that lock on the phase, you'd have to change
> their correction/detection loop, but overall, they should still work.
>
>
> Attila Kinali
>
>
> [1] http://www.febo.com/time-freq/wwvb/spectracom/index.html
>
> --
> The trouble with you, Shev, is you don't say anything until you've saved
> up a whole truckload of damned heavy brick arguments and then you dump
> them all out and never look at the bleeding body mangled beneath the heap
> -- Tirin, The Dispossessed, U. Le Guin
>
> _______________________________________________
> time-nuts mailing list -- time-nuts-***@public.gmane.org
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>

[Jim Lux]

On 3/15/12 7:49 AM, J. Forster wrote:
> Suppose the modulation is not present. The output of the phase detector
> that steers the local standard ot indicator works correctly.
>
> Now reverse the 60 kHz carrier. The phase detector works exactly thye
> opposite way... wrong.
>
> Now alternate between 0 and 190 degrees.
>
> The loop alternate works between exactly right and exactly wrong... it
> dithers around and the output is a measure of the ratio of 1's to 0's and
> is utterly useless.
>

and the cleverness of the Costas loop is that it uses (an estimate of)
the current data bit (the output of the I arm) to flip the sign of the
error signal from the quadrature arm.

There's a lot of scope for modification of the basic linear Costas loop.
Hard/soft limiters in either or both arms, you've got three filters
(the two arm filters and the loop filter) to fool with, plus all sorts
of schemes using "data aiding" where you get feedback from your symbol
slicer to help do a better job on the carrier tracking.

You can also run your loop with hard limited signal input (makes the
"mixers" turn into XOR gates).

If you don't need the bits in real time (i.e. you can tolerate some
latency), then you can also build tracking loops that effectively "look
into the future"; i.e. make decisions on carrier and bit at time t using
future data from t>now, as well as t=[-infinity, now].


Enormous literature out there on this, and it's been grist for many a
Master's or PhD dissertation.
All in a quest to get ever closer to the Shannon limit...

[J. Forster]

Why make it simple when complicated also works?

-John

============



> On 3/15/12 7:49 AM, J. Forster wrote:
>> Suppose the modulation is not present. The output of the phase detector
>> that steers the local standard ot indicator works correctly.
>>
>> Now reverse the 60 kHz carrier. The phase detector works exactly thye
>> opposite way... wrong.
>>
>> Now alternate between 0 and 190 degrees.
>>
>> The loop alternate works between exactly right and exactly wrong... it
>> dithers around and the output is a measure of the ratio of 1's to 0's
>> and
>> is utterly useless.
>>
>
> and the cleverness of the Costas loop is that it uses (an estimate of)
> the current data bit (the output of the I arm) to flip the sign of the
> error signal from the quadrature arm.
>
> There's a lot of scope for modification of the basic linear Costas loop.
> Hard/soft limiters in either or both arms, you've got three filters
> (the two arm filters and the loop filter) to fool with, plus all sorts
> of schemes using "data aiding" where you get feedback from your symbol
> slicer to help do a better job on the carrier tracking.
>
> You can also run your loop with hard limited signal input (makes the
> "mixers" turn into XOR gates).
>
> If you don't need the bits in real time (i.e. you can tolerate some
> latency), then you can also build tracking loops that effectively "look
> into the future"; i.e. make decisions on carrier and bit at time t using
> future data from t>now, as well as t=[-infinity, now].
>
>
> Enormous literature out there on this, and it's been grist for many a
> Master's or PhD dissertation.
> All in a quest to get ever closer to the Shannon limit...
>
> _______________________________________________
> time-nuts mailing list -- time-nuts-***@public.gmane.org
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>

[Jim Lux]

On 3/15/12 8:10 AM, J. Forster wrote:
> Why make it simple when complicated also works?
>
> -John

Can't get your doctorate doing something someone else has already
done...<grin>
>

>>
>> Enormous literature out there on this, and it's been grist for many a
>> Master's or PhD dissertation.
>> All in a quest to get ever closer to the Shannon limit...
>>

[J. Forster]

Frankly, my dear, I'd rather be a generalist.

-John

============

> On 3/15/12 8:10 AM, J. Forster wrote:
>> Why make it simple when complicated also works?
>>
>> -John
>
> Can't get your doctorate doing something someone else has already
> done...<grin>
>>
>
>>>
>>> Enormous literature out there on this, and it's been grist for many a
>>> Master's or PhD dissertation.
>>> All in a quest to get ever closer to the Shannon limit...
>>>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts-***@public.gmane.org
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>

[Attila Kinali]

On Thu, 15 Mar 2012 07:49:15 -0700 (PDT)
"J. Forster" <jfor-9KbcMkp5tujQT0dZR+***@public.gmane.org> wrote:

> Suppose the modulation is not present. The output of the phase detector
> that steers the local standard ot indicator works correctly.
>
> Now reverse the 60 kHz carrier. The phase detector works exactly thye
> opposite way... wrong.
>
> Now alternate between 0 and 190 degrees.
>
> The loop alternate works between exactly right and exactly wrong... it
> dithers around and the output is a measure of the ratio of 1's to 0's and
> is utterly useless.

That under the assumption, that they do not make sure that the average
phase is zeros out (or converges to 90°). I have not found anything
taht suggests this... on the other hand, there is nothing that suggests
the contrary either.

But you didnt address my main point yet: The phase of the WWVB signal
is already fluctuating a lot, just by natural occuring atmospherical
"noise". If a 180° phase shift does destabilize your PLL, what does
these "shifts" which are much larger do?

Attila Kinali

--
The trouble with you, Shev, is you don't say anything until you've saved
up a whole truckload of damned heavy brick arguments and then you dump
them all out and never look at the bleeding body mangled beneath the heap
-- Tirin, The Dispossessed, U. Le Guin

[Chris Albertson]

On Wed, Mar 14, 2012 at 3:08 PM, Brooke Clarke <brooke-***@public.gmane.org> wrote:
> Hi:
>
> I sure would like a WWVB BPSK receiver for the new modulation.  The
> processing gains described in the paper John Seamons linked describes
> processing gains that are tens of dB above what's possible with the old AM
> data format.  John has also measures the experimental phase modulation
> testing, see:  http://www.jks.com/wwvb/wwvb.html
> The WWB paper "New Improved System for WWVB Broadcast" given at the 43rd
> PTTI November 2011 is at:  http://jks.com/wwvb.pdf
>
> Part of the processing gain comes directly from the BPSK modulation and that
> amounts to a little over 10 dB improvement, but there's a further 18 dB gain
> to be had by accumulating an hours worth of data and processing that.
>
> I'm sure in time there will be plenty of low cost ICs designed to receive
> the new signal, but my guess is that many Time Nuts would like to be in on
> the ground floor.  Also NIST probably would like to get reports on the new
> signal when they do test transmissions.
>
> How to move forward?

I'd say to go "100% SDR". In other words a simple front and that
pushes as much of the functionality into software as possible. The
carrier is only 60K. That is low enough that one can directly
digitize the RF using an ADC that samples at only 192K/sec.
192K/Sec is a common sample rte for high-end audio and you can buy a
24-bit dual channel interface for under $200.

So I'd use an antenna (the best would be a shielded loop with many
turns of wire but ferrite "loop stick" could work) Follow that be an
RF amp and very narrow filter and then the above 24-bit 192K ADC.
With a 24-bit ADC you may not need any automatic gain control. So yo
are almost sampling the voltage off the antenna, so that's why I
called it "100% SDR"

Once the data are inside the computer the very next step might be an FFT.

Some good easy to use software is this:
http://gnuradio.org/redmine/projects/gnuradio/wiki/GNURadioCompanion
Using this you simply drop function blocks on a screen and connect
then with lines. It's a visual drag and drop way to build a signal
processor

As an example to build a spectrum analyzer you drop a block the
represents your audio interface, another for the FFT operator and a
third for a graph. Connect them together. Then plug in a
microphone and point it as something you want to plot.

If you do use the simplest possible RF front and that can still work,
followed by a common off the shelf audio interface and then a simple
graphical programming environment you then will have a wider community
of people working on this. You could use more complex technology
like an FPGA or a DSP chip but then the number of people who would
know how to help will be a number close to zero.

The RF front end does not need to be sophisticated because much of the
selectivity and gain control is done in software. You just need a
hard low pass filter to remove everything above 60KHz


>
> --
> Have Fun,
>
> Brooke Clarke, N6GCE
> http://www.PRC68.com
> http://www.end2partygovernment.com/Brooke4Congress.html
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts-***@public.gmane.org
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



--

Chris Albertson
Redondo Beach, California

[Chuck Forsberg WA7KGX N2469R]

Asus has a $30 Xonar PCI soundcard that should do the job.
I have two of the the more expensive pci-e versions. Some motherboards
can do a/d at 192 but not as well as the Xonar.

I made a 60 KHz antenna by winding a zillion turns on a ferrite
rod and a padder going into the gate of a FET. This was in the
1970s.

On 03/14/2012 03:35 PM, Chris Albertson wrote:
> On Wed, Mar 14, 2012 at 3:08 PM, Brooke Clarke<brooke-***@public.gmane.org> wrote:
>> Hi:
>>
>> I sure would like a WWVB BPSK receiver for the new modulation. The
>> processing gains described in the paper John Seamons linked describes
>> processing gains that are tens of dB above what's possible with the old AM
>> data format. John has also measures the experimental phase modulation
>> testing, see: http://www.jks.com/wwvb/wwvb.html
>> The WWB paper "New Improved System for WWVB Broadcast" given at the 43rd
>> PTTI November 2011 is at: http://jks.com/wwvb.pdf
>>
>> Part of the processing gain comes directly from the BPSK modulation and that
>> amounts to a little over 10 dB improvement, but there's a further 18 dB gain
>> to be had by accumulating an hours worth of data and processing that.
>>
>> I'm sure in time there will be plenty of low cost ICs designed to receive
>> the new signal, but my guess is that many Time Nuts would like to be in on
>> the ground floor. Also NIST probably would like to get reports on the new
>> signal when they do test transmissions.
>>
>> How to move forward?
> I'd say to go "100% SDR". In other words a simple front and that
> pushes as much of the functionality into software as possible. The
> carrier is only 60K. That is low enough that one can directly
> digitize the RF using an ADC that samples at only 192K/sec.
> 192K/Sec is a common sample rte for high-end audio and you can buy a
> 24-bit dual channel interface for under $200.
>
> So I'd use an antenna (the best would be a shielded loop with many
> turns of wire but ferrite "loop stick" could work) Follow that be an
> RF amp and very narrow filter and then the above 24-bit 192K ADC.
> With a 24-bit ADC you may not need any automatic gain control. So yo
> are almost sampling the voltage off the antenna, so that's why I
> called it "100% SDR"
>
> Once the data are inside the computer the very next step might be an FFT.
>
> Some good easy to use software is this:
> http://gnuradio.org/redmine/projects/gnuradio/wiki/GNURadioCompanion
> Using this you simply drop function blocks on a screen and connect
> then with lines. It's a visual drag and drop way to build a signal
> processor
>
> As an example to build a spectrum analyzer you drop a block the
> represents your audio interface, another for the FFT operator and a
> third for a graph. Connect them together. Then plug in a
> microphone and point it as something you want to plot.
>
> If you do use the simplest possible RF front and that can still work,
> followed by a common off the shelf audio interface and then a simple
> graphical programming environment you then will have a wider community
> of people working on this. You could use more complex technology
> like an FPGA or a DSP chip but then the number of people who would
> know how to help will be a number close to zero.
>
> The RF front end does not need to be sophisticated because much of the
> selectivity and gain control is done in software. You just need a
> hard low pass filter to remove everything above 60KHz
>
>
>> --
>> Have Fun,
>>
>> Brooke Clarke, N6GCE
>> http://www.PRC68.com
>> http://www.end2partygovernment.com/Brooke4Congress.html
>>
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts-***@public.gmane.org
>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>
>

--
Chuck Forsberg WA7KGX N2469R caf-***@public.gmane.org www.omen.com
Developer of Industrial ZMODEM(Tm) for Embedded Applications
Omen Technology Inc "The High Reliability Software"
10255 NW Old Cornelius Pass Portland OR 97231 503-614-0430

[Ben Gamari]

Looks like this bounced as I sent from the wrong address. Better late
than never.

On Wed, 14 Mar 2012 15:46:48 -0700, Chuck Forsberg WA7KGX N2469R <caf-***@public.gmane.org> wrote:
> Asus has a $30 Xonar PCI soundcard that should do the job.
> I have two of the the more expensive pci-e versions. Some motherboards
> can do a/d at 192 but not as well as the Xonar.
>
Even better: a USB DVB card [1]. For $30 you have a few million 8-bit
I/Q samples per second and an interface to Gnu Radio. The possibilities
are nearly endless.

Cheers,

- Ben

[1] http://sdr.osmocom.org/trac/wiki/rtl-sdr

[Marek Peca]

I will share my few bits of worked experience. But it may seem obvious.

> I'd say to go "100% SDR". In other words a simple front and that
> pushes as much of the functionality into software as possible. The
> carrier is only 60K. That is low enough that one can directly
> digitize the RF using an ADC that samples at only 192K/sec.

Not necesarilly. I received 77.5kHz very well in first sampling mirror,
sampling using ADS7813 16bit ADC @44ksps, yielding carrier at 10.5kHz in
discrete-time domain.

> 192K/Sec is a common sample rte for high-end audio and you can buy a
> 24-bit dual channel interface for under $200.

Beware, there are lots of sigma-delta ADCs for this purpose and I am in
doubt whether they could perform better than less-bits SAR ADC.

> So I'd use an antenna (the best would be a shielded loop with many
> turns of wire but ferrite "loop stick" could work) Follow that be an
> RF amp and very narrow filter and then the above 24-bit 192K ADC.

I must object a little bit against "RF" and "very narrow" -- I have used
very sloooooooow amplifiers (they were in a shack, original purpose DC
measurement up to some 100s of kHz) and nothing narrow (or even tuned) --
except the ferrite rod itself. The rest were 2 ICs (amp & ADC) and simple
RC network.

Worked very well, including few centimeters from laptop's CCFL inverter.


Best regards,
Marek

[Poul-Henning Kamp]

In message <***@tesla>, Marek Peca writes:

>I will share my few bits of worked experience. But it may seem obvious.
>
>> I'd say to go "100% SDR". In other words a simple front and that
>> pushes as much of the functionality into software as possible. The
>> carrier is only 60K. That is low enough that one can directly
>> digitize the RF using an ADC that samples at only 192K/sec.
>
>Not necesarilly. I received 77.5kHz very well in first sampling mirror,
>sampling using ADS7813 16bit ADC @44ksps, yielding carrier at 10.5kHz in
>discrete-time domain.

Here's a really interesting platform for VLF SDR work:

http://www.seeedstudio.com/depot/dso-nano-v2-p-681.html?cPath=174

1MSPS 12 bit ADC, input amplifier/attenuator, display, USB interface,
and rechargeable lithium battery.

For $89...

Too bad it doesn't have a 10MHz reference clock input for time-nuttery.


--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk-***@public.gmane.org | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

[Fuqua, Bill L]

I know I am not one of the good-ole-boys here but I'd say go 100% SDR with your PC without an external
A/D converter. Ok, how would you do this? You use under sampling.
Many A/D converter systems use a sample and hold before the A/D converter.
If you do the same before your sound card (your A/D converter) and drive the S&H with an audio output from your sound
card, say at 6.1 kHz you would get a 1 kHz signal into your sound card to process. You can call it under sampling
aliasing or whatever.
By the way Ten Tec patented an under sampling scheme many years ago when they started into the SDR
business.

[Peter Monta]

> Many A/D converter systems use a sample and hold before the A/D converter.
> If you do the same before your sound card (your A/D converter) and drive the S&H with an audio output from your sound
> card, say at 6.1 kHz you would get a 1 kHz signal into your sound card to process. You can call it under sampling
> aliasing or whatever.

Yes, this would work, but instantaneous sampling would tend to alias
in many harmonics, requiring good prefiltering at RF (if you can call
60 kHz RF). Just as easy would be a mixer from CMOS switches, driven
say at 50 kHz to get 10 kHz into the sound card.

The WWVB signal apparently has a double-sided bandwidth of about 1200
Hz (not clear from the paper if that means 3 dB bandwidth or something
else). To get all of the signal something like 2 or 3 kHz might be
safest, requiring an IF of several kHz at least.

Cheers,
Peter

[Chris Albertson]

The major advantage of simply sampling at 192K is that it is so
simple. Not much hardware outside of a good audio interface is
required.

But the mixer is attractive because then you can make it a quadrature
mixer and then sample with both stereo channels. One then could use
a more common 44.1 or 48K sample rate.

You trade a bit of hardware up front for reduced processing
requirements later.


On Thu, Mar 15, 2012 at 12:38 AM, Peter Monta <pmonta-***@public.gmane.org> wrote:
>> Many A/D converter systems use a sample and hold before the A/D converter.
>> If you do the same before your sound card (your A/D converter) and drive the S&H with an audio output from your sound
>> card, say at 6.1 kHz you would get a 1 kHz signal into your sound card to process. You can call it under sampling
>> aliasing or whatever.
>
> Yes, this would work, but instantaneous sampling would tend to alias
> in many harmonics, requiring good prefiltering at RF (if you can call
> 60 kHz RF).  Just as easy would be a mixer from CMOS switches, driven
> say at 50 kHz to get 10 kHz into the sound card.
>
> The WWVB signal apparently has a double-sided bandwidth of about 1200
> Hz (not clear from the paper if that means 3 dB bandwidth or something
> else).  To get all of the signal something like 2 or 3 kHz might be
> safest, requiring an IF of several kHz at least.
>
> Cheers,
> Peter
>
> _______________________________________________
> time-nuts mailing list -- time-nuts-***@public.gmane.org
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



--

Chris Albertson
Redondo Beach, California

[Marek Peca]

> I know I am not one of the good-ole-boys here but I'd say go 100% SDR
> with your PC without an external A/D converter. Ok, how would you do
> this? You use under sampling. Many A/D converter systems use a sample
> and hold before the A/D converter. If you do the same before your sound
> card (your A/D converter) and drive the S&H with an audio output from
> your sound card, say at 6.1 kHz you would get a 1 kHz signal into your
> sound card to process. You can call it under sampling aliasing or
> whatever.

Unfortunately, this works only with a few types of sound cards. Last
several years, most of PC audio cards use sigma-delta ADCs and there is no
way to get quality undersampling. Tried it. I can not tell there was no
signal -- there were really some carriers mirrors, but on odd frequencies
and largely attenuated.

Greetings,
Marek

[Peter Monta]

> Part of the processing gain comes directly from the BPSK modulation and that
> amounts to a little over 10 dB improvement, but there's a further 18 dB gain
> to be had by accumulating an hours worth of data and processing that.

That part of the paper bothered me. There's nothing preventing a
receiver from averaging the current AM-only signal for a long time.
They shouldn't be taking credit for that.

A receiver capable of integrating over a few hours *using the existing
signal* would arguably achieve many of the stated goals of the paper,
including the jammer resistance.

Maybe the new signal is an improvement, and I would have nothing
against it if it doesn't hurt the overall phase stability, but apples
should be compared with apples.

Cheers,
Peter

[Chuck Forsberg WA7KGX N2469R]

How about this: Generate a precise 60 KHz signal from a GPSDO's 10 MHz.
Modulate it with 1 bit audio generated by a Linux program which would know
about DST. Feed this to a loop around the house to give a good 60 Khz
signal
inside but little outside.

I have thought of this to keep my Atomic Clocks working :-)

--
Chuck Forsberg WA7KGX N2469R caf-***@public.gmane.org www.omen.com
Developer of Industrial ZMODEM(Tm) for Embedded Applications
Omen Technology Inc "The High Reliability Software"
10255 NW Old Cornelius Pass Portland OR 97231 503-614-0430

[Chris Albertson]

On Thu, Mar 15, 2012 at 1:48 AM, Chuck Forsberg WA7KGX N2469R
<caf-***@public.gmane.org> wrote:
> How about this:  Generate a precise 60 KHz signal from a GPSDO's 10 MHz.
> Modulate it with 1 bit audio generated by a Linux program which would know
> about DST.

The standard NTP source code distribution comes with a program to
generate the time code. So you'd not have the write it yourself.
It's purpose is to test the the WWV drivers n NTP. It is not built
by default, from memory the source is in a directory called "test".

But for those radio clocks in your house the new WWVB signal should
just work. They will not notice the phase modulation
Chris Albertson
Redondo Beach, California

[Fuqua, Bill L]

You are correct, however, I suppose you are using a loop antenna with a relatively high Q.
The "antenna gain" is related to the Q when you have an antenna with a diameter much less than
a wavelength.
With a Q of 100 you would have a bandwidth of .6 kHz, If you go to say 20.3333kHz you would not
need that high of a Q.
Now, why do you need 1200 Hz bandwidth? Is it sending over 1kbaud data rate? I have not
looked at the details. Just recall the data rate was 1 bit/second for time.
1200Hz at 60 kHz would represent a very low Q antenna only 5 or so.
If you use CMOS switches you will still get aliasing at odd harmonics. So you would still need
a front end filter.
If you want a closer sampling frequency just make a simple frequency multiplier and you still
can use the sound card output.
The real point is where does SDR begin. As I said with CMOS switches you are effectively multiplying
or mixing the incomming signal with square waves which have odd harmonics and you still get aliasing.


73
Bill wa4lav
PS Just retired Friday. Maybe I will have some time to catch up with these discussions.

> Many A/D converter systems use a sample and hold before the A/D converter.
> If you do the same before your sound card (your A/D converter) and drive the S&H with an audio output from your sound
> card, say at 6.1 kHz you would get a 1 kHz signal into your sound card to process. You can call it under sampling
> aliasing or whatever.

Yes, this would work, but instantaneous sampling would tend to alias
in many harmonics, requiring good prefiltering at RF (if you can call
60 kHz RF). Just as easy would be a mixer from CMOS switches, driven
say at 50 kHz to get 10 kHz into the sound card.

The WWVB signal apparently has a double-sided bandwidth of about 1200
Hz (not clear from the paper if that means 3 dB bandwidth or something
else). To get all of the signal something like 2 or 3 kHz might be
safest, requiring an IF of several kHz at least.

Cheers,
Peter

[Demian Martin]

There are a number of sound cards (and have been for 10 years now) that can
capture up to 95 KHz with extraordinary fidelity. They sample at 192 KHz and
usually have "24" bit converters good tor 20+ bits. These can capture the
complete FM MPX output pretty easily.

Some of the newer ADC's have less that .001% THD at 192 KHz sampling. The
AK5394a for example has -105 dB THD at 1 KHz. Can be had as a chip for about
$22 ea if you want to build your own. Some current motherboards have an
SPDIF input that can handle the 192 KHz sample rate. The next challenge is
getting the OS to handle it, not difficult.
Demian

[Dennis Ferguson]

On 14 Mar, 2012, at 18:08 , Brooke Clarke wrote:
> The WWB paper "New Improved System for WWVB Broadcast" given at the 43rd PTTI November 2011 is at: http://jks.com/wwvb.pdf
>
> Part of the processing gain comes directly from the BPSK modulation and that amounts to a little over 10 dB improvement, but there's a further 18 dB gain to be had by accumulating an hours worth of data and processing that.

It is a little interesting that the PTTI paper left out some
of the interesting details one would need to actually decode
the new signal, in particular the specification of the 14
second "Sync" sequence, which is necessary to know to find
the alignment of minutes, and the value of the "60-bit
hour-synchronization code", which defines the sequence
of phase reversals in each minute's modulation in an
hour and, as I understand it, is necessary to know to
take full advantage of the hour-averaging thing.

I assume this might have been done to allow the company
which participated in the design of the signal to complete
a receiver for it before they start transmitting that
way while keeping anyone else from starting a receiver
project until after the transmissions start?

Dennis Ferguson

[michael batchelor]

So, I just recently started trying to resurrect a Spectracom 8160A reference oscillator. I'm assuming this is proposed WWVB change going to bite me in the butt on this project as well. Not sure how it differs from units like the HP 117, but my understanding is that most of the old VLF receivers work about the same.


Do I understand this correctly?  I'm kind of new to all this. Jeez, what a time to get back in a hobby.


Michael - KA7ZNZ

[michael batchelor]

OK,  John Forster and I have been kicking around a few things off line, and he
suggested I should bring part of it back on line. Maybe I have a few details
wrong, or maybe I have them right and some folks are unaware of them.

My concern about the BPSK, and breaking my Spectracom oscillator, is really
centered on loosing my NIST traceable reference oscillator. I don't care one
bit what time of day it is.

I wrote:
>> I did poke around a bit, and it appears that WWVB is still an approved

>> frequency standard, so any oscillator which is phased locked to WWVB
>> qualifies as an "NIST traceable" standard
>> reference oscillator, which is my only concern.

John wrote:
>Good news! Thanks.

I wrote:
>> A GPS disciplined oscillator, regardless of how stable/accurate it may be, is
>> not an NIST traceable standard unless NIST decides to certify the Naval
>> Observatory as a standard. Or I suppose NIST could take over the GPS
>> correction uploads.but I don't see that happening any time soon. That's
>> really outside their mission boundary.


Maybe a few things have changed in the metrology world in past few years, but the
GPS based oscillators are controlled by the Naval Observatory clocks, not the
NIST clocks. So while an HP-117 or a Spectracon 8160 oscillator phase locked to
WWVB is "by definition" an NIST traceable standard so long as it is in lock and
you have a valid lock history, a GPS unit, even though it may be just as stable an
oscillator, isn't an NIST traceable standard without a whole lot of equipment to
validate that NIST and the GPS system are in sync.

(There is/was actually a commercial solution to verify this, but it isn't/wasn't cheap.)

For all you metrology guys out there, has any of this recently changed?

So my interest in keep my Spectracom going isn't just to keep a "stable" 10 MHz
oscillator in the lab. The GPS will give me a stable signal. My interest is in keeping
a "stable and "traceable" 10 MHz signal going. After all, all our old gray-hair tax
dollars paid for this government service over the past 5 decades. Why should we
get kicked off the bus now? It isn't like we want anything new. Just don't break
what we've already paid for.

Michael

[Charles P. Steinmetz]

Michael wrote:

>My concern about the BPSK, and breaking my Spectracom oscillator, is really
>centered on loosing my NIST traceable reference oscillator. I don't care one
>bit what time of day it is. * * *
>
>So while an HP-117 or a Spectracon 8160 oscillator phase locked to
>WWVB is "by definition" an NIST traceable standard so long as it is
>in lock and
>you have a valid lock history, a GPS unit, even though it may be
>just as stable an
>oscillator, isn't an NIST traceable standard without a whole lot of
>equipment to
>validate that NIST and the GPS system are in sync. * * *
>
>For all you metrology guys out there, has any of this recently changed?


These NIST links should get you started:

http://nist.gov/traceability/

http://tf.nist.gov/general/pdf/2297.pdf

http://www.nist.gov/pml/div688/grp40/gpsarchive.cfm

<http://www.google.com/url?sa=t&rct=j&q=&source=web&cd=1&ved=0CEEQFjAA&url=http%3A%2F%2Ftf.boulder.nist.gov%2Fgeneral%2Fpdf%2F1502.pdf&ei=CmRtT9fSB4ji0gGAm7n_Bg&usg=AFQjCNGO0uxF4gdRhld-L8PEERwEmaGgGg>


Note that only *measurement results* are "traceable" -- not local
standards. There is no such thing as a "NIST traceable
standard." And even with a WWVB reference, one needs an "internal
measurement assurance program" to support a claim of traceability for
the measurements that one makes. Just having an HP-117 or Spectracon
8160 is not sufficient to claim NIST traceability for one's
measurements. Note that less than 1% of claimed "NIST traceability"
really is traceable to NIST. For all the stuff on eBay that claims
to be "NIST calibrated" (Really? Did you take that to Boulder for
calibration?) or "NIST traceable," only a negligible amount of it really is.


Best regards,

Charles

[michael batchelor]

Charles wrote:

>And even with a WWVB reference, one needs an "internal
>measurement assurance program" to support a claim of traceability for
>the measurements that one makes.
Correct. You must not only maintain a laboratory condition for your lab,
but you must keep - and validate - your phase data. Just having the lock
light "ON" at the time of measurement is insufficient. I've run a metrology
lab in the past, so the methods and procedures for both the electronic
and mechanical standards aren't lost on me..

But having the oscillator broken is a dead-nuts failure.That's not lost on
me either.