Discussion:
new WWVB BPSK dev board
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Tom Van Baak
2018-12-04 02:11:30 UTC
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At long last, a complete WWVB 60 kHz BPSK dev board is available:

https://universal-solder.ca/product/everset-es100-cob-wwvb-60khz-bpsk-receiver-kit-with-2-antennas/

Note it includes the antenna(s). Also has links to documentation.

It would be very nice if a bunch of time nuts around the country played with these and reported results.

Prior to this, the only device that you could buy which used the enhanced WWVB format was the La Crosse 404-1235UA-SS UltrAtomic clock. It was not developer friendly, so a dev board with the Everset ES100 chip is good news.

The maker / hacker / Arduino crowd may enjoy a fresh source of accurate time; something independent of GPS or NTP. Some technical postings about reception quality, acquisition speed, and timing precision would be most welcome.

/tvb


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Paul Bicknell
2018-12-04 02:20:16 UTC
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Hi All

There is a 60 Khz frequency standard operating in the UK

So do the two signals interfere with each other?
Paul

-----Original Message-----
From: time-nuts [mailto:time-nuts-***@lists.febo.com] On Behalf Of Tom
Van Baak
Sent: 04 December 2018 02:12
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] new WWVB BPSK dev board

At long last, a complete WWVB 60 kHz BPSK dev board is available:

https://universal-solder.ca/product/everset-es100-cob-wwvb-60khz-bpsk-receiv
er-kit-with-2-antennas/

Note it includes the antenna(s). Also has links to documentation.

It would be very nice if a bunch of time nuts around the country played with
these and reported results.

Prior to this, the only device that you could buy which used the enhanced
WWVB format was the La Crosse 404-1235UA-SS UltrAtomic clock. It was not
developer friendly, so a dev board with the Everset ES100 chip is good news.

The maker / hacker / Arduino crowd may enjoy a fresh source of accurate
time; something independent of GPS or NTP. Some technical postings about
reception quality, acquisition speed, and timing precision would be most
welcome.

/tvb


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Bob kb8tq
2018-12-04 02:37:46 UTC
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Hi

The interference “front” turns out to be over the US rather than over the UK. Power,
distance, and propagation all get into the “why”. The answer is that you get crazy
fades and phase shifts as a result.

Bob
Post by Paul Bicknell
Hi All
There is a 60 Khz frequency standard operating in the UK
So do the two signals interfere with each other?
Paul
-----Original Message-----
Van Baak
Sent: 04 December 2018 02:12
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] new WWVB BPSK dev board
https://universal-solder.ca/product/everset-es100-cob-wwvb-60khz-bpsk-receiv
er-kit-with-2-antennas/
Note it includes the antenna(s). Also has links to documentation.
It would be very nice if a bunch of time nuts around the country played with
these and reported results.
Prior to this, the only device that you could buy which used the enhanced
WWVB format was the La Crosse 404-1235UA-SS UltrAtomic clock. It was not
developer friendly, so a dev board with the Everset ES100 chip is good news.
The maker / hacker / Arduino crowd may enjoy a fresh source of accurate
time; something independent of GPS or NTP. Some technical postings about
reception quality, acquisition speed, and timing precision would be most
welcome.
/tvb
_______________________________________________
To unsubscribe, go to
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and follow the instructions there.
-----
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Paul Bicknell
2018-12-04 02:46:23 UTC
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Hi thank you Bob for the mail

Do you realise the 60 Khz Transmitter in the UK was moved from Rugby in the
centre of England north by more than 200 miles
Paul

-----Original Message-----
From: time-nuts [mailto:time-nuts-***@lists.febo.com] On Behalf Of Bob
kb8tq
Sent: 04 December 2018 02:38
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] new WWVB BPSK dev board

Hi

The interference "front" turns out to be over the US rather than over the
UK. Power,
distance, and propagation all get into the "why". The answer is that you get
crazy
fades and phase shifts as a result.

Bob
Post by Paul Bicknell
Hi All
There is a 60 Khz frequency standard operating in the UK
So do the two signals interfere with each other?
Paul
-----Original Message-----
Van Baak
Sent: 04 December 2018 02:12
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] new WWVB BPSK dev board
https://universal-solder.ca/product/everset-es100-cob-wwvb-60khz-bpsk-receiv
Post by Paul Bicknell
er-kit-with-2-antennas/
Note it includes the antenna(s). Also has links to documentation.
It would be very nice if a bunch of time nuts around the country played with
these and reported results.
Prior to this, the only device that you could buy which used the enhanced
WWVB format was the La Crosse 404-1235UA-SS UltrAtomic clock. It was not
developer friendly, so a dev board with the Everset ES100 chip is good news.
The maker / hacker / Arduino crowd may enjoy a fresh source of accurate
time; something independent of GPS or NTP. Some technical postings about
reception quality, acquisition speed, and timing precision would be most
welcome.
/tvb
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Post by Paul Bicknell
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Alex Pummer
2018-12-04 03:32:13 UTC
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that address is incorrect:  Website: www.EversetClocks.com

Alex
Post by Paul Bicknell
Hi All
There is a 60 Khz frequency standard operating in the UK
So do the two signals interfere with each other?
Paul
-----Original Message-----
Van Baak
Sent: 04 December 2018 02:12
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] new WWVB BPSK dev board
https://universal-solder.ca/product/everset-es100-cob-wwvb-60khz-bpsk-receiv
er-kit-with-2-antennas/
Note it includes the antenna(s). Also has links to documentation.
It would be very nice if a bunch of time nuts around the country played with
these and reported results.
Prior to this, the only device that you could buy which used the enhanced
WWVB format was the La Crosse 404-1235UA-SS UltrAtomic clock. It was not
developer friendly, so a dev board with the Everset ES100 chip is good news.
The maker / hacker / Arduino crowd may enjoy a fresh source of accurate
time; something independent of GPS or NTP. Some technical postings about
reception quality, acquisition speed, and timing precision would be most
welcome.
/tvb
_______________________________________________
To unsubscribe, go to
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and follow the instructions there.
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Checked by AVG - www.avg.com
Version: 2016.0.8048 / Virus Database: 4793/15883 - Release Date: 08/14/18
Internal Virus Database is out of date.
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paul swed
2018-12-04 04:01:01 UTC
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I am on the east coast and the everset chips work very well I have had a
unit for musty be 5 years and ran tests for them. So at least here in
Boston it does very fine.
Hope that helps.
Regards
Paul
WB8TSL
that address is incorrect: Website: www.EversetClocks.com
Alex
Post by Paul Bicknell
Hi All
There is a 60 Khz frequency standard operating in the UK
So do the two signals interfere with each other?
Paul
-----Original Message-----
Tom
Post by Paul Bicknell
Van Baak
Sent: 04 December 2018 02:12
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] new WWVB BPSK dev board
https://universal-solder.ca/product/everset-es100-cob-wwvb-60khz-bpsk-receiv
Post by Paul Bicknell
er-kit-with-2-antennas/
Note it includes the antenna(s). Also has links to documentation.
It would be very nice if a bunch of time nuts around the country played
with
Post by Paul Bicknell
these and reported results.
Prior to this, the only device that you could buy which used the enhanced
WWVB format was the La Crosse 404-1235UA-SS UltrAtomic clock. It was not
developer friendly, so a dev board with the Everset ES100 chip is good
news.
Post by Paul Bicknell
The maker / hacker / Arduino crowd may enjoy a fresh source of accurate
time; something independent of GPS or NTP. Some technical postings about
reception quality, acquisition speed, and timing precision would be most
welcome.
/tvb
_______________________________________________
To unsubscribe, go to
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
-----
No virus found in this message.
Checked by AVG - www.avg.com
08/14/18
Post by Paul Bicknell
Internal Virus Database is out of date.
_______________________________________________
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Post by Paul Bicknell
and follow the instructions there.
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Eric Garner
2018-12-04 05:02:24 UTC
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This seems relatively expensive for a little wirebonded board of this type.
It seems like the sort of thing that you would normally find on aliexpress
or ebay for a few dollars.

It it because the es100 is otherwise unobtanium?

Eric
Post by Tom Van Baak
https://universal-solder.ca/product/everset-es100-cob-wwvb-60khz-bpsk-receiver-kit-with-2-antennas/
Note it includes the antenna(s). Also has links to documentation.
It would be very nice if a bunch of time nuts around the country played
with these and reported results.
Prior to this, the only device that you could buy which used the enhanced
WWVB format was the La Crosse 404-1235UA-SS UltrAtomic clock. It was not
developer friendly, so a dev board with the Everset ES100 chip is good news.
The maker / hacker / Arduino crowd may enjoy a fresh source of accurate
time; something independent of GPS or NTP. Some technical postings about
reception quality, acquisition speed, and timing precision would be most
welcome.
/tvb
_______________________________________________
To unsubscribe, go to
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and follow the instructions there.
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paul swed
2018-12-04 14:50:20 UTC
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I assume thats exactly the case. I also thought it was pretty high.
The actual clocks are about $50 or less I believe. So the board seems a bit
off.
Regards
Paul
WB8TSL
Post by Eric Garner
This seems relatively expensive for a little wirebonded board of this type.
It seems like the sort of thing that you would normally find on aliexpress
or ebay for a few dollars.
It it because the es100 is otherwise unobtanium?
Eric
https://universal-solder.ca/product/everset-es100-cob-wwvb-60khz-bpsk-receiver-kit-with-2-antennas/
Post by Tom Van Baak
Note it includes the antenna(s). Also has links to documentation.
It would be very nice if a bunch of time nuts around the country played
with these and reported results.
Prior to this, the only device that you could buy which used the enhanced
WWVB format was the La Crosse 404-1235UA-SS UltrAtomic clock. It was not
developer friendly, so a dev board with the Everset ES100 chip is good
news.
Post by Tom Van Baak
The maker / hacker / Arduino crowd may enjoy a fresh source of accurate
time; something independent of GPS or NTP. Some technical postings about
reception quality, acquisition speed, and timing precision would be most
welcome.
/tvb
_______________________________________________
To unsubscribe, go to
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
_______________________________________________
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Majdi S. Abbas
2018-12-04 16:25:40 UTC
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$69 CAD is roughly $50 USD.

Expensive for what it is but easier to work with than gutting a working clock and no more expensive.

I ordered one. Curious to see what sort of precision we can get from an i2c interface.

If nothing else I suppose I can toss a six digit i2c 7 segment module at it and roll my own WWVB desk clock.

—msa
Post by paul swed
I assume thats exactly the case. I also thought it was pretty high.
The actual clocks are about $50 or less I believe. So the board seems a bit
off.
Regards
Paul
WB8TSL
Post by Eric Garner
This seems relatively expensive for a little wirebonded board of this type.
It seems like the sort of thing that you would normally find on aliexpress
or ebay for a few dollars.
It it because the es100 is otherwise unobtanium?
Eric
https://universal-solder.ca/product/everset-es100-cob-wwvb-60khz-bpsk-receiver-kit-with-2-antennas/
Post by Tom Van Baak
Note it includes the antenna(s). Also has links to documentation.
It would be very nice if a bunch of time nuts around the country played
with these and reported results.
Prior to this, the only device that you could buy which used the enhanced
WWVB format was the La Crosse 404-1235UA-SS UltrAtomic clock. It was not
developer friendly, so a dev board with the Everset ES100 chip is good
news.
Post by Tom Van Baak
The maker / hacker / Arduino crowd may enjoy a fresh source of accurate
time; something independent of GPS or NTP. Some technical postings about
reception quality, acquisition speed, and timing precision would be most
welcome.
/tvb
_______________________________________________
To unsubscribe, go to
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
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paul swed
2018-12-04 16:34:12 UTC
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Majdi good for you. You will have fun. OK precision thats a slippery slope.
The documentation will indicate the sequence time and length and as I
recall the chip produces a result every 90 seconds using the long phase.
There is a short phase after you have acquired that is something like 30
seconds. But I recall it was tricky aligning to the second. That was the
BPSK edge. Anyhow it does work.
I hear they ship some arduino code with it. That would be fun to look at. I
used whats was called a SXB at the time. Worked fine.
Regards
Paul
Post by Majdi S. Abbas
$69 CAD is roughly $50 USD.
Expensive for what it is but easier to work with than gutting a working
clock and no more expensive.
I ordered one. Curious to see what sort of precision we can get from an i2c interface.
If nothing else I suppose I can toss a six digit i2c 7 segment module at
it and roll my own WWVB desk clock.
—msa
Post by paul swed
I assume thats exactly the case. I also thought it was pretty high.
The actual clocks are about $50 or less I believe. So the board seems a
bit
Post by paul swed
off.
Regards
Paul
WB8TSL
Post by Eric Garner
This seems relatively expensive for a little wirebonded board of this
type.
Post by paul swed
Post by Eric Garner
It seems like the sort of thing that you would normally find on
aliexpress
Post by paul swed
Post by Eric Garner
or ebay for a few dollars.
It it because the es100 is otherwise unobtanium?
Eric
https://universal-solder.ca/product/everset-es100-cob-wwvb-60khz-bpsk-receiver-kit-with-2-antennas/
Post by paul swed
Post by Eric Garner
Post by Tom Van Baak
Note it includes the antenna(s). Also has links to documentation.
It would be very nice if a bunch of time nuts around the country played
with these and reported results.
Prior to this, the only device that you could buy which used the
enhanced
Post by paul swed
Post by Eric Garner
Post by Tom Van Baak
WWVB format was the La Crosse 404-1235UA-SS UltrAtomic clock. It was
not
Post by paul swed
Post by Eric Garner
Post by Tom Van Baak
developer friendly, so a dev board with the Everset ES100 chip is good
news.
Post by Tom Van Baak
The maker / hacker / Arduino crowd may enjoy a fresh source of accurate
time; something independent of GPS or NTP. Some technical postings
about
Post by paul swed
Post by Eric Garner
Post by Tom Van Baak
reception quality, acquisition speed, and timing precision would be
most
Post by paul swed
Post by Eric Garner
Post by Tom Van Baak
welcome.
/tvb
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Post by paul swed
and follow the instructions there.
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Bob kb8tq
2018-12-04 16:48:23 UTC
Reply
Permalink
Hi

The I2C clock rate is going to matter a bit in terms of what you can achieve.
Since the device is targeted at low power, the max practical baud rate may
not be very high. I2C can have a lot of wait in it ... There are a lot of registers
dumped after each “reception attempt”.

There also is the basic question of how the IRQ flag relates to the time the
chip “sees”. If it’s actually WWVB time sync’d then that’s a useful thing.

None of this is likely to be an issue in a wall clock. If they can run at a “tens of ms”
sort of level that’s more than good enough. We really want to get to microseconds
don’t we :)

Bob
Post by Majdi S. Abbas
$69 CAD is roughly $50 USD.
Expensive for what it is but easier to work with than gutting a working clock and no more expensive.
I ordered one. Curious to see what sort of precision we can get from an i2c interface.
If nothing else I suppose I can toss a six digit i2c 7 segment module at it and roll my own WWVB desk clock.
—msa
Post by paul swed
I assume thats exactly the case. I also thought it was pretty high.
The actual clocks are about $50 or less I believe. So the board seems a bit
off.
Regards
Paul
WB8TSL
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and foll
Tim Shoppa
2018-12-04 17:00:02 UTC
Reply
Permalink
Because of the Q of WWVB's transmit antenna (at least 300 by my back of the
envelope estimates), I don't think we could ever claim a WWVB PPS edge
sharper than 5 milliseconds and that might be optimistic.

Tim N3QE
Post by Bob kb8tq
Hi
The I2C clock rate is going to matter a bit in terms of what you can achieve.
Since the device is targeted at low power, the max practical baud rate may
not be very high. I2C can have a lot of wait in it ... There are a lot of registers
dumped after each “reception attempt”.
There also is the basic question of how the IRQ flag relates to the time the
chip “sees”. If it’s actually WWVB time sync’d then that’s a useful thing.
None of this is likely to be an issue in a wall clock. If they can run at
a “tens of ms”
sort of level that’s more than good enough. We really want to get to microseconds
don’t we :)
Bob
Post by Majdi S. Abbas
$69 CAD is roughly $50 USD.
Expensive for what it is but easier to work with than gutting a working
clock and no more expensive.
Post by Majdi S. Abbas
I ordered one. Curious to see what sort of precision we can get from an
i2c interface.
Post by Majdi S. Abbas
If nothing else I suppose I can toss a six digit i2c 7 segment module at
it and roll my own WWVB desk clock.
Post by Majdi S. Abbas
—msa
Post by paul swed
I assume thats exactly the case. I also thought it was pretty high.
The actual clocks are about $50 or less I believe. So the board seems a
bit
Post by Majdi S. Abbas
Post by paul swed
off.
Regards
Paul
WB8TSL
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jimlux
2018-12-04 18:02:33 UTC
Reply
Permalink
Post by Tim Shoppa
Because of the Q of WWVB's transmit antenna (at least 300 by my back of the
envelope estimates), I don't think we could ever claim a WWVB PPS edge
sharper than 5 milliseconds and that might be optimistic.
Sure you can.. you do a matched filter to the waveform, so you're not
just looking at a single zero crossing or cycle. Getting fraction of a
degree phase accuracy from a strong signal is entirely possible.

A Q of 300 implies a bandwidth of 200Hz, which would, if a single
section, be a delay of a few milliseconds. But that delay should be
constant. What might be the limit on precision is whether the delay
through the antenna and the ultimate radiated phase changes with, say,
temperature or soil properties.
Post by Tim Shoppa
Tim N3QE
Post by Bob kb8tq
Hi
The I2C clock rate is going to matter a bit in terms of what you can achieve.
Since the device is targeted at low power, the max practical baud rate may
not be very high. I2C can have a lot of wait in it ... There are a lot of registers
dumped after each “reception attempt”.
There also is the basic question of how the IRQ flag relates to the time the
chip “sees”. If it’s actually WWVB time sync’d then that’s a useful thing.
None of this is likely to be an issue in a wall clock. If they can run at
a “tens of ms”
sort of level that’s more than good enough. We really want to get to microseconds
don’t we :)
Bob
Post by Majdi S. Abbas
$69 CAD is roughly $50 USD.
Expensive for what it is but easier to work with than gutting a working
clock and no more expensive.
Post by Majdi S. Abbas
I ordered one. Curious to see what sort of precision we can get from an
i2c interface.
Post by Majdi S. Abbas
If nothing else I suppose I can toss a six digit i2c 7 segment module at
it and roll my own WWVB desk clock.
Post by Majdi S. Abbas
—msa
Post by paul swed
I assume thats exactly the case. I also thought it was pretty high.
The actual clocks are about $50 or less I believe. So the board seems a
bit
Post by Majdi S. Abbas
Post by paul swed
off.
Regards
Paul
WB8TSL
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a
Poul-Henning Kamp
2018-12-04 18:49:49 UTC
Reply
Permalink
--------
Post by jimlux
Post by Tim Shoppa
Because of the Q of WWVB's transmit antenna (at least 300 by my back of the
envelope estimates), I don't think we could ever claim a WWVB PPS edge
sharper than 5 milliseconds and that might be optimistic.
Sure you can.. you do a matched filter to the waveform, so you're not
just looking at a single zero crossing or cycle. Getting fraction of a
degree phase accuracy from a strong signal is entirely possible.
See also: Loran-C ?

And with the new phase modulation, you can do get down in low
microseconds at tau=1, but the atmosphere will ruin longer taus.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
***@FreeBSD.ORG | TCP/IP since RFC 956
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Never attribute to malice what can adequately be explained by incompetence.

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John Ackermann. N8UR
2018-12-04 17:03:40 UTC
Reply
Permalink
I ordered one, too.  It looks like there's an IRQ line that goes low +/- 100 ms of the second mark.  It will be interesting to see how stable that is in real life.
Post by Majdi S. Abbas
$69 CAD is roughly $50 USD.
Expensive for what it is but easier to work with than gutting a working
clock and no more expensive.
I ordered one. Curious to see what sort of precision we can get from an i2c interface.
If nothing else I suppose I can toss a six digit i2c 7 segment module
at it and roll my own WWVB desk clock.
—msa
Post by paul swed
I assume thats exactly the case. I also thought it was pretty high.
The actual clocks are about $50 or less I believe. So the board seems
a bit
Post by paul swed
off.
Regards
Paul
WB8TSL
Post by Eric Garner
This seems relatively expensive for a little wirebonded board of
this type.
Post by paul swed
Post by Eric Garner
It seems like the sort of thing that you would normally find on
aliexpress
Post by paul swed
Post by Eric Garner
or ebay for a few dollars.
It it because the es100 is otherwise unobtanium?
Eric
https://universal-solder.ca/product/everset-es100-cob-wwvb-60khz-bpsk-receiver-kit-with-2-antennas/
Post by paul swed
Post by Eric Garner
Post by Tom Van Baak
Note it includes the antenna(s). Also has links to documentation.
It would be very nice if a bunch of time nuts around the country
played
Post by paul swed
Post by Eric Garner
Post by Tom Van Baak
with these and reported results.
Prior to this, the only device that you could buy which used the
enhanced
Post by paul swed
Post by Eric Garner
Post by Tom Van Baak
WWVB format was the La Crosse 404-1235UA-SS UltrAtomic clock. It
was not
Post by paul swed
Post by Eric Garner
Post by Tom Van Baak
developer friendly, so a dev board with the Everset ES100 chip is
good
Post by paul swed
Post by Eric Garner
news.
Post by Tom Van Baak
The maker / hacker / Arduino crowd may enjoy a fresh source of
accurate
Post by paul swed
Post by Eric Garner
Post by Tom Van Baak
time; something independent of GPS or NTP. Some technical postings
about
Post by paul swed
Post by Eric Garner
Post by Tom Van Baak
reception quality, acquisition speed, and timing precision would be
most
Post by paul swed
Post by Eric Garner
Post by Tom Van Baak
welcome.
/tvb
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Post by paul swed
and follow the instructions there.
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gandalfg8--- via time-nuts
2018-12-04 12:11:59 UTC
Reply
Permalink
Hi Paul,



It was shifted over 11 years ago, very obligingly timed to follow my move from the South East to Scotland:-),

so I suspect any resulting propogational changes would have been well documented by now.



Nigel GM8PZR



Hi thank you Bob for the mail

Do you realise the 60 Khz Transmitter in the UK was moved from Rugby in the
centre of England north by more than 200 miles
Paul
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Paul Bicknell
2018-12-04 23:57:24 UTC
Reply
Permalink
Hi Nigel

I moved from Warwickshire to west Sussex south of the downs 20 years ago
and all was OK But since it moved I have not bean able to use the 60 Khz
reference I am thinking of setting up a reference to use the one in France
I think it is 192 Khz
And then I can do a frequency difference between the 2
Also Looking for a rabid

Best regards Paul

-----Original Message-----
From: time-nuts [mailto:time-nuts-***@lists.febo.com] On Behalf Of
gandalfg8--- via time-nuts
Sent: 04 December 2018 12:12
To: time-***@lists.febo.com
Cc: ***@aol.com
Subject: [time-nuts] new WWVB BPSK dev board

Hi Paul,

It was shifted over 11 years ago, very obligingly timed to follow my move
from the South East to Scotland:-),

so I suspect any resulting propogational changes would have been well
documented by now.

Nigel GM8PZR

Hi thank you Bob for the mail

Do you realise the 60 Khz Transmitter in the UK was moved from Rugby in the
centre of England north by more than 200 miles
Paul
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Gilles Clement
2018-12-05 02:29:05 UTC
Reply
Permalink
Hi,
In France the carrier frequency is 162khz (Allouis)
Phase modulated over one minute.
Gilles.

Envoyé de mon iPad
Post by Paul Bicknell
Hi Nigel
I moved from Warwickshire to west Sussex south of the downs 20 years ago
and all was OK But since it moved I have not bean able to use the 60 Khz
reference I am thinking of setting up a reference to use the one in France
I think it is 192 Khz
And then I can do a frequency difference between the 2
Also Looking for a rabid
Best regards Paul
-----Original Message-----
gandalfg8--- via time-nuts
Sent: 04 December 2018 12:12
Subject: [time-nuts] new WWVB BPSK dev board
Hi Paul,
It was shifted over 11 years ago, very obligingly timed to follow my move
from the South East to Scotland:-),
so I suspect any resulting propogational changes would have been well documented by now.
Nigel GM8PZR
Hi thank you Bob for the mail
Do you realise the 60 Khz Transmitter in the UK was moved from Rugby in the
centre of England north by more than 200 miles
Paul
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Richard (Rick) Karlquist
2018-12-05 14:29:01 UTC
Reply
Permalink
Post by Gilles Clement
Hi,
In France the carrier frequency is 162khz (Allouis)
Phase modulated over one minute.
Gilles.
Interesting: isn't 162 kHz within the European
Long Wave Broadcast Band? Wouldn't there be a
problem with QRM from these megawatt stations?
Excuse the naive questions; we don't have longwave
in the states, so no experience here.

Rick

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jimlux
2018-12-05 14:42:04 UTC
Reply
Permalink
Post by Gilles Clement
Hi,
In France the carrier frequency is 162khz (Allouis)
Phase modulated over one minute.
Gilles.
Interesting:  isn't 162 kHz within the European
Long Wave Broadcast Band?  Wouldn't there be a
problem with QRM from these megawatt stations?
Excuse the naive questions; we don't have longwave
in the states, so no experience here.
Indeed. I was just tuning around with some of the Kiwi SDRs suggested by
phk. Front end selectivity or plenty of dynamic range in the ADC would
be important.

I suppose, though, that the integration time is quite long, so from a
"recovering the bits" standpoint, the detection bandwidth can be quite
narrow, and your desired signal might be buried in the grass of the raw
samples.


I also tried to see some 60kHz in the US.. no joy yet.. but I'll load up
the client and see if I can capture some bits.



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Attila Kinali
2018-12-05 14:47:00 UTC
Reply
Permalink
On Wed, 5 Dec 2018 06:29:01 -0800
Post by Richard (Rick) Karlquist
Interesting: isn't 162 kHz within the European
Long Wave Broadcast Band? Wouldn't there be a
problem with QRM from these megawatt stations?
Excuse the naive questions; we don't have longwave
in the states, so no experience here.
Indeed it is. Allouis is a former LW band radio station,
which the French used as time signal station as well[1].
But that also means that it is a much stronger transmitter
than e.g. DCF77 (2MW vs 50kW if wikipedia is correct)

Attila Kinali

[1] https://en.wikipedia.org/wiki/Allouis_longwave_transmitter
--
It is upon moral qualities that a society is ultimately founded. All
the prosperity and technological sophistication in the world is of no
use without that foundation.
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Magnus Danielson
2018-12-05 14:57:50 UTC
Reply
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Hi,
Post by Attila Kinali
On Wed, 5 Dec 2018 06:29:01 -0800
Post by Richard (Rick) Karlquist
Interesting: isn't 162 kHz within the European
Long Wave Broadcast Band? Wouldn't there be a
problem with QRM from these megawatt stations?
Excuse the naive questions; we don't have longwave
in the states, so no experience here.
Indeed it is. Allouis is a former LW band radio station,
which the French used as time signal station as well[1].
But that also means that it is a much stronger transmitter
than e.g. DCF77 (2MW vs 50kW if wikipedia is correct)
I think I recall that they where running Allouis at half power, but then
1 MW is not all bad.

Looking at it using a Kiwi receiver just north of Stockholm, it comes in
nice and clean with 100 Hz sidebands from what looks like a PM whose 4th
sideband is nearly suppressed, so is 8th, 12/13, 21... so slightly more
that 4th and multiples.

The fun part is that I coould very quickly check this sitting with my
laptop at work, remote sensing and SDR at it's finest.

It would be fun to develop some extensions for KiwiSDR.

The Loran-C/Chayka plug-in does not calculate position, so already there
would be some fun little mini-project to attempt.

Cheers,
Magnus
Post by Attila Kinali
Attila Kinali
[1] https://en.wikipedia.org/wiki/Allouis_longwave_transmitter
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Poul-Henning Kamp
2018-12-05 15:27:10 UTC
Reply
Permalink
--------
Post by Magnus Danielson
Looking at it using a Kiwi receiver just north of Stockholm, it comes in
nice and clean with 100 Hz sidebands from what looks like a PM whose 4th
sideband is nearly suppressed, so is 8th, 12/13, 21... so slightly more
that 4th and multiples.
It looks like both 162 and 198 has gotten more modulation after
Loran-C disappeared, and I wonder if submarines are involved ?
Post by Magnus Danielson
The Loran-C/Chayka plug-in does not calculate position, so already there
would be some fun little mini-project to attempt.
If only there were some Loran-C stations left :-)
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
***@FreeBSD.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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Magnus Danielson
2018-12-05 16:17:40 UTC
Reply
Permalink
Hi,
Post by Poul-Henning Kamp
--------
Post by Magnus Danielson
Looking at it using a Kiwi receiver just north of Stockholm, it comes in
nice and clean with 100 Hz sidebands from what looks like a PM whose 4th
sideband is nearly suppressed, so is 8th, 12/13, 21... so slightly more
that 4th and multiples.
It looks like both 162 and 198 has gotten more modulation after
Loran-C disappeared, and I wonder if submarines are involved ?
Maybe, or there is other relevant reasons.
Post by Poul-Henning Kamp
Post by Magnus Danielson
The Loran-C/Chayka plug-in does not calculate position, so already there
would be some fun little mini-project to attempt.
If only there were some Loran-C stations left :-)
I could see the GRI 8000 Chayka constellation thought.

Cheers,
Magnus

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Poul-Henning Kamp
2018-12-05 16:41:21 UTC
Reply
Permalink
--------
Post by Magnus Danielson
Post by Poul-Henning Kamp
Post by Magnus Danielson
The Loran-C/Chayka plug-in does not calculate position, so already there
would be some fun little mini-project to attempt.
If only there were some Loran-C stations left :-)
I could see the GRI 8000 Chayka constellation thought.
I have never been able to calculate a plausible position from that
here in Denmark, I'd be very interested to see your calculations if
you succeed.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
***@FreeBSD.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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Magnus Danielson
2018-12-05 18:00:46 UTC
Reply
Permalink
Hi,
Post by Poul-Henning Kamp
--------
Post by Magnus Danielson
Post by Poul-Henning Kamp
Post by Magnus Danielson
The Loran-C/Chayka plug-in does not calculate position, so already there
would be some fun little mini-project to attempt.
If only there were some Loran-C stations left :-)
I could see the GRI 8000 Chayka constellation thought.
I have never been able to calculate a plausible position from that
here in Denmark, I'd be very interested to see your calculations if
you succeed.
Oh, yes, I just remembered that there is a suitable receiver which I
could borrow next week.

The antenna and receiver that we setup sits in a remote location away
from our "mountain", so it's alone in the woods. As QRM-free as you can
get it in this neighborhood. I could see the GRI 8000 network, so it
should be possible to do something.

Cheers,
Magnus

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Club-Internet Clemgill
2018-12-05 17:53:33 UTC
Reply
Permalink
Hi,
The Allouis phase modulation is as follows :
- sawtooth phase shift of the 162kHz carrier with 40rad/sec slope => +/- 1 rad shift => +/- 6,36Hz carrier frequency shift
- sequence of full sawtooth periods of length 100msec => frequency 10Hz
- one full period sawtooth codes a « 0 » bit
- two full periods sawtooth code a « 1 » bit
- One bit only is coded per second in each minute => 59 bits available because...
- 59th second is silent (no phase modulation)

Gilles.
Post by Poul-Henning Kamp
--------
Post by Magnus Danielson
Looking at it using a Kiwi receiver just north of Stockholm, it comes in
nice and clean with 100 Hz sidebands from what looks like a PM whose 4th
sideband is nearly suppressed, so is 8th, 12/13, 21... so slightly more
that 4th and multiples.
It looks like both 162 and 198 has gotten more modulation after
Loran-C disappeared, and I wonder if submarines are involved ?
Post by Magnus Danielson
The Loran-C/Chayka plug-in does not calculate position, so already there
would be some fun little mini-project to attempt.
If only there were some Loran-C stations left :-)
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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Poul-Henning Kamp
2018-12-05 20:23:59 UTC
Reply
Permalink
--------
Post by Club-Internet Clemgill
- One bit only is coded per second in each minute => 59 bits available because...
- 59th second is silent (no phase modulation)
I belive this is wrong.

The timecode (substantially the same as DCF77) occupies only one
bit (the first) in each second, but more bits are encoded each
second after the first one, I belive for some kind of "telecontrol"
scheme.

See 4th plot from the top for (old) evidence:

http://phk.freebsd.dk/loran-c/CW/
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
***@FreeBSD.ORG | TCP/IP since RFC 956
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Pieter-Tjerk de Boer
2018-12-05 21:54:29 UTC
Reply
Permalink
Post by Poul-Henning Kamp
--------
Post by Club-Internet Clemgill
- One bit only is coded per second in each minute => 59 bits available because...
- 59th second is silent (no phase modulation)
I belive this is wrong.
The timecode (substantially the same as DCF77) occupies only one
bit (the first) in each second, but more bits are encoded each
second after the first one, I belive for some kind of "telecontrol"
scheme.
Yes, that's correct.
In the remaining part in each second, more bits are transmitted, using
a more complex three-level modulation scheme, with a data packet format
defined for it.
However, it has never been used for actual user data (so I was told by
someone from CFHM, the organisation behind this time signal).

So effectively it is only transmitting idle frames, which boils down to a
1-minute-long ever repeating pseudo-random sequence.
Being completely predictable, this sequence could be used to improve timing
receiver accuracy.

The Allouis signal can be seen live here: http://websdr.ewi.utwente.nl:8901/tdf/

And here's another, perhaps even more nutty, example of decoding the signal:
http://www.pa3fwm.nl/signals/clock-lille-flandres/

Regards,
Pieter-Tjerk, PA3FWM


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Tim Shoppa
2018-12-04 16:35:19 UTC
Reply
Permalink
Thanks for the heads up Tom! I ordered one and if it comes before the end
of the year I may have some time over the holidays to do acquisition test
from Maryland and maybe some cross-comparison with GPS PPS.

Here in Maryland I have somewhat unreliable reception on commercial
non-BPSK WWVB clocks at my house. My Casio Waveceptor watch is 99%+
reliable when I'm asleep on the 2nd floor but much less likely to work in
the basement. I can reliably hear the amplitude-keyed WWVB carrier on a LF
receiver with a homebrew loop (about 3 foot by 3 foot) in the evenings but
it takes some imagination to think I can hear it during the daytime.

Tim N3QE
Post by Tom Van Baak
https://universal-solder.ca/product/everset-es100-cob-wwvb-60khz-bpsk-receiver-kit-with-2-antennas/
Note it includes the antenna(s). Also has links to documentation.
It would be very nice if a bunch of time nuts around the country played
with these and reported results.
Prior to this, the only device that you could buy which used the enhanced
WWVB format was the La Crosse 404-1235UA-SS UltrAtomic clock. It was not
developer friendly, so a dev board with the Everset ES100 chip is good news.
The maker / hacker / Arduino crowd may enjoy a fresh source of accurate
time; something independent of GPS or NTP. Some technical postings about
reception quality, acquisition speed, and timing precision would be most
welcome.
/tvb
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David G. McGaw
2018-12-04 16:52:44 UTC
Reply
Permalink
It does a very good job of pulling the signal out of the noise.  It
works in NH, traditionally a fringe region, in all but the most shielded
of rooms.  I also had occasion to test it for Everset in Kangerlussuaq,
Greenland.  I found it had no trouble acquiring at any time of the day. 
If the ES100 does not do well enough for you, there is supposedly an
ES200 available that uses a longer sequence for even more sensitivity.

The one thing I wish is that there were access to the synchronized
analog signal and/or a 1PPS.  Even a top of the minute would be useful. 
It only has the I2C digital interface.

73,

David N1HAC
Post by Tim Shoppa
Thanks for the heads up Tom! I ordered one and if it comes before the end
of the year I may have some time over the holidays to do acquisition test
from Maryland and maybe some cross-comparison with GPS PPS.
Here in Maryland I have somewhat unreliable reception on commercial
non-BPSK WWVB clocks at my house. My Casio Waveceptor watch is 99%+
reliable when I'm asleep on the 2nd floor but much less likely to work in
the basement. I can reliably hear the amplitude-keyed WWVB carrier on a LF
receiver with a homebrew loop (about 3 foot by 3 foot) in the evenings but
it takes some imagination to think I can hear it during the daytime.
Tim N3QE
Post by Tom Van Baak
https://universal-solder.ca/product/everset-es100-cob-wwvb-60khz-bpsk-receiver-kit-with-2-antennas/
Note it includes the antenna(s). Also has links to documentation.
It would be very nice if a bunch of time nuts around the country played
with these and reported results.
Prior to this, the only device that you could buy which used the enhanced
WWVB format was the La Crosse 404-1235UA-SS UltrAtomic clock. It was not
developer friendly, so a dev board with the Everset ES100 chip is good news.
The maker / hacker / Arduino crowd may enjoy a fresh source of accurate
time; something independent of GPS or NTP. Some technical postings about
reception quality, acquisition speed, and timing precision would be most
welcome.
/tvb
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Adrian Godwin
2018-12-04 16:59:28 UTC
Reply
Permalink
I understand why a low-volume shipment of what started as a board costing a
few pennies costs $50, but does that simply mean that low-cost parts aren't
the right answer for this sort of application ?

How would an SDR based on a raspberry pi zero, a suitable ADC and a tuned
rx circuit compare ?
It does a very good job of pulling the signal out of the noise. It
works in NH, traditionally a fringe region, in all but the most shielded
of rooms. I also had occasion to test it for Everset in Kangerlussuaq,
Greenland. I found it had no trouble acquiring at any time of the day.
If the ES100 does not do well enough for you, there is supposedly an
ES200 available that uses a longer sequence for even more sensitivity.
The one thing I wish is that there were access to the synchronized
analog signal and/or a 1PPS. Even a top of the minute would be useful.
It only has the I2C digital interface.
73,
David N1HAC
Post by Tim Shoppa
Thanks for the heads up Tom! I ordered one and if it comes before the end
of the year I may have some time over the holidays to do acquisition test
from Maryland and maybe some cross-comparison with GPS PPS.
Here in Maryland I have somewhat unreliable reception on commercial
non-BPSK WWVB clocks at my house. My Casio Waveceptor watch is 99%+
reliable when I'm asleep on the 2nd floor but much less likely to work in
the basement. I can reliably hear the amplitude-keyed WWVB carrier on a
LF
Post by Tim Shoppa
receiver with a homebrew loop (about 3 foot by 3 foot) in the evenings
but
Post by Tim Shoppa
it takes some imagination to think I can hear it during the daytime.
Tim N3QE
https://universal-solder.ca/product/everset-es100-cob-wwvb-60khz-bpsk-receiver-kit-with-2-antennas/
Post by Tim Shoppa
Post by Tom Van Baak
Note it includes the antenna(s). Also has links to documentation.
It would be very nice if a bunch of time nuts around the country played
with these and reported results.
Prior to this, the only device that you could buy which used the
enhanced
Post by Tim Shoppa
Post by Tom Van Baak
WWVB format was the La Crosse 404-1235UA-SS UltrAtomic clock. It was not
developer friendly, so a dev board with the Everset ES100 chip is good
news.
Post by Tim Shoppa
Post by Tom Van Baak
The maker / hacker / Arduino crowd may enjoy a fresh source of accurate
time; something independent of GPS or NTP. Some technical postings about
reception quality, acquisition speed, and timing precision would be most
welcome.
/tvb
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jimlux
2018-12-04 17:58:35 UTC
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Permalink
Post by Adrian Godwin
I understand why a low-volume shipment of what started as a board costing a
few pennies costs $50, but does that simply mean that low-cost parts aren't
the right answer for this sort of application ?
How would an SDR based on a raspberry pi zero, a suitable ADC and a tuned
rx circuit compare ?
"suitable ADC" and "tuned Rx circuit" would greatly interact.. the more
narrow band your Rx, the fewer bits you'd need in your ADC - The Teensy
($20 arduino clone) can sample at well over 100ksps with a 16 bit (13-14
ENOB) differential input, and I'll bet you could make a simple PSK
demodulator in software, either on the Teensy or on the host PC (which
could be a RPi or Beagle) connected via USB.


https://www.pjrc.com/store/teensy32.html

They also sell a higher performance audio interface that might be useful:
https://www.pjrc.com/store/teensy3_audio.html
Although it's 44.1 kHz sample rate - but might actually support other rates.


So the real question is where can you find an inexpensive 60kHz front
end amplifier.

The computer (whether arduino, teensy, beagle, or Rpi) isn't the
limiting thing, it's the RF to digital interface. -

Find a $20 60kHz narrow band receiver/ADC , and the rest is straightforward.




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Poul-Henning Kamp
2018-12-04 18:47:13 UTC
Reply
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--------
Post by Adrian Godwin
How would an SDR based on a raspberry pi zero, a suitable ADC and a tuned
rx circuit compare ?
You can do a LOT more fun stuff that way, and it isn't even hard.

If you clock a 1MSPS ADC from an OCXO you can discipline it to whatever
VLF signal you prefer (or an ensemble of them)
--
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Hal Murray
2018-12-04 18:07:42 UTC
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The one thing I wish is that there were access to the synchronized analog
signal and/or a 1PPS.  Even a top of the minute would be useful.  It only
has the I2C digital interface.
It also has an IRQ signal.

The data sheet said it's 100 ms after the second, but I didn't see any
accuracy info but I didn't look carefully.
--
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David G. McGaw
2018-12-04 18:34:03 UTC
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As was said, IRQ delay is +/-100 mS from the second edge, hardly what a
Time-Nut is looking for.

David
Post by Hal Murray
The one thing I wish is that there were access to the synchronized analog
signal and/or a 1PPS.  Even a top of the minute would be useful.  It only
has the I2C digital interface.
It also has an IRQ signal.
The data sheet said it's 100 ms after the second, but I didn't see any
accuracy info but I didn't look carefully.
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Hal Murray
2018-12-04 19:00:09 UTC
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Post by David G. McGaw
As was said, IRQ delay is +/-100 mS from the second edge, hardly what a
Time-Nut is looking for.
There is no problem with a delay as long as it is constant. If I know what it
is, then I can correct for it.

The problem is the noise/jitter on the delay. I'm sure somebody will have
data soon.
--
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David G. McGaw
2018-12-04 20:08:29 UTC
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That is the specified jitter. They have also said in communications that it has about 50mS resolution. That is as close as they are willing to say a system can be synchronized with it. Perhaps someone will discover a clever way to enhance that.

BTW, I have been told it has also been successfully tested for lock in Brazil. Is there anyone in Australia want to give it a try? Perth is almost directly opposite Fort Collins. :-)

David N1HAC


On 12/4/18 2:00 PM, Hal Murray wrote:




As was said, IRQ delay is +/-100 mS from the second edge, hardly what a
Time-Nut is looking for.



There is no problem with a delay as long as it is constant. If I know what it
is, then I can correct for it.

The problem is the noise/jitter on the delay. I'm sure somebody will have
data soon.




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Poul-Henning Kamp
2018-12-04 20:14:03 UTC
Reply
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--------
Post by David G. McGaw
BTW, I have been told it has also been successfully tested for lock in Brazil. Is there anyone in Australia want to give it a try? Perth is almost directly opposite Fort Collins. :-)
Write a WWVB extension to KiwiSDR so you can try it all over the world ?
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
***@FreeBSD.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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Bob kb8tq
2018-12-04 20:21:15 UTC
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Hi

We’ve been chatting about how drop dead simple it is to spend a couple minutes and come
up with a SDR for the new modulation for …. ummm ….. errr …. how many years now? :)
So far not a lot has turned up.

Bob
Post by Poul-Henning Kamp
--------
Post by David G. McGaw
BTW, I have been told it has also been successfully tested for lock in Brazil. Is there anyone in Australia want to give it a try? Perth is almost directly opposite Fort Collins. :-)
Write a WWVB extension to KiwiSDR so you can try it all over the world ?
--
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FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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Poul-Henning Kamp
2018-12-04 20:31:25 UTC
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--------
Post by Bob kb8tq
We’ve been chatting about how drop dead simple it is to spend a couple minutes and come
up with a SDR for the new modulation for …. ummm ….. errr …. how many years now? :)
So far not a lot has turned up.
All I can say is that people dont know what they're missing ;-)
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
***@FreeBSD.ORG | TCP/IP since RFC 956
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David Van Horn
2018-12-05 13:16:41 UTC
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For other reasons and other bands (650m), I am very interested in narrow band SDR, but I have not found a platform to get started on.


-----Original Message-----
From: time-nuts <time-nuts-***@lists.febo.com> On Behalf Of Poul-Henning Kamp
Sent: Tuesday, December 4, 2018 1:31 PM
To: Discussion of precise time and frequency measurement <time-***@lists.febo.com>; Bob kb8tq <***@n1k.org>
Subject: Re: [time-nuts] new WWVB BPSK dev board

--------
Post by Bob kb8tq
We’ve been chatting about how drop dead simple it is to spend a couple
minutes and come up with a SDR for the new modulation for …. ummm …..
errr …. how many years now? :) So far not a lot has turned up.
All I can say is that people dont know what they're missing ;-)


--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
***@FreeBSD.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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jimlux
2018-12-04 21:12:48 UTC
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Post by Bob kb8tq
Hi
We’ve been chatting about how drop dead simple it is to spend a couple minutes and come
up with a SDR for the new modulation for …. ummm ….. errr …. how many years now? :)
So far not a lot has turned up.
if someone will digitize the signal at some reasonable data rate and bit
depth and send me some minutes of data, I'll see if I can code up a
simple decoder that would run on a low end processor.

It's just BPSK at 1 bit/second, after all.

I maintain that it's the lack of a cheap RF front end that is the sticky
point.
Post by Bob kb8tq
Bob
Post by Poul-Henning Kamp
--------
Post by David G. McGaw
BTW, I have been told it has also been successfully tested for lock in Brazil. Is there anyone in Australia want to give it a try? Perth is almost directly opposite Fort Collins. :-)
Write a WWVB extension to KiwiSDR so you can try it all over the world ?
--
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Attila Kinali
2018-12-04 21:48:16 UTC
Reply
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On Tue, 4 Dec 2018 13:12:48 -0800
Post by jimlux
I maintain that it's the lack of a cheap RF front end that is the sticky
point.
Doing a 2-3 stage transistor based amplifier should give the signal
enough gain to be sampled with the ADC of a uC. I have such a design
sitting around, that I did a couple of years back for DCF77, but never
got around to actually built it (see attachment).

It is meant to be run from 4V, so that one can use an unstable/noisy
5V source with an 4V LDO and should give ~70dB of total gain. I used
BC547 in the simulation, but any NPN with decent h_fe and f_t should
do (eg 2N2222, 2N3904,...). The 2N5484 is a bit harder to replace,
as I selected it for its low V_th and narrow specified V_th range.

All that is needed for this to work is a tuned antenna, ie a ferrite
rod with a capcitor on it that is approximately tuned to 60/77.5kHz.

Attila Kinali
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Bob kb8tq
2018-12-04 22:37:06 UTC
Reply
Permalink
Hi

Given the large “fade” of WWVB over a 24 hour period (it’s not always ground
wave ….) most decent receivers in the past have run a front end with AGC on it.
Indeed 24 bit ADC’s ( > 16 bit ENOB) are out there for not a massive amount of
money.

It is a bit unclear just how much fade you need to compensate for until you get
past the “that’s enough” point. There are a number of nasty points in the country
you would need to check out. Since you also are trying to deal with an enormous
amount of “crud” at the same time, there may not be an exact answer.

Bob
Post by Attila Kinali
On Tue, 4 Dec 2018 13:12:48 -0800
Post by jimlux
I maintain that it's the lack of a cheap RF front end that is the sticky
point.
Doing a 2-3 stage transistor based amplifier should give the signal
enough gain to be sampled with the ADC of a uC. I have such a design
sitting around, that I did a couple of years back for DCF77, but never
got around to actually built it (see attachment).
It is meant to be run from 4V, so that one can use an unstable/noisy
5V source with an 4V LDO and should give ~70dB of total gain. I used
BC547 in the simulation, but any NPN with decent h_fe and f_t should
do (eg 2N2222, 2N3904,...). The 2N5484 is a bit harder to replace,
as I selected it for its low V_th and narrow specified V_th range.
All that is needed for this to work is a tuned antenna, ie a ferrite
rod with a capcitor on it that is approximately tuned to 60/77.5kHz.
Attila Kinali
--
<JaberWorky> The bad part of Zurich is where the degenerates
throw DARK chocolate at you.
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jimlux
2018-12-04 22:44:38 UTC
Reply
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Post by Attila Kinali
On Tue, 4 Dec 2018 13:12:48 -0800
Post by jimlux
I maintain that it's the lack of a cheap RF front end that is the sticky
point.
Doing a 2-3 stage transistor based amplifier should give the signal
enough gain to be sampled with the ADC of a uC. I have such a design
sitting around, that I did a couple of years back for DCF77, but never
got around to actually built it (see attachment).
It is meant to be run from 4V, so that one can use an unstable/noisy
5V source with an 4V LDO and should give ~70dB of total gain. I used
BC547 in the simulation, but any NPN with decent h_fe and f_t should
do (eg 2N2222, 2N3904,...). The 2N5484 is a bit harder to replace,
as I selected it for its low V_th and narrow specified V_th range.
All that is needed for this to work is a tuned antenna, ie a ferrite
rod with a capcitor on it that is approximately tuned to 60/77.5kHz.
Attila Kinali
17 passive components and 4 active components. plus the loopstick and
tuning cap. I think you'd need pretty substantial volumes to get the
"assembled and delivered" price below $20.

I usually use the rule of thumb that the BOM cost has to be 1/5th to
1/10th the retail price. So $2.
You might get there.. the MMBF5484 is 12 cents in qty 100. I assume you
can find a NPN for less than 10 cents - The LDO might be the most
expensive part.





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Attila Kinali
2018-12-05 14:03:04 UTC
Reply
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On Tue, 4 Dec 2018 14:44:38 -0800
Post by jimlux
17 passive components and 4 active components. plus the loopstick and
tuning cap. I think you'd need pretty substantial volumes to get the
"assembled and delivered" price below $20.
Oh. Sorry, I misunderstood. My design was never intended for mass-production,
but for a one-off board to experiment with DCF77. For that, a couple
transistors and passives are cheaper than getting some kind of chip.
While for mass production, even at "low" volumes of 1000/y, I'd immediatly
go for a small chip to do the frontend.


Attila Kinali
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the prosperity and technological sophistication in the world is of no
use without that foundation.
-- Miss Matheson, The Diamond Age, Neal Stephenson

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Poul-Henning Kamp
2018-12-04 22:52:52 UTC
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--------
Post by Attila Kinali
On Tue, 4 Dec 2018 13:12:48 -0800
I maintain that it's the lack of a cheap RF front end that is the sticky point.
Then you have misunderstood how little you actually need.

This is the "front-end" I ran most of my VLF experiments with:

http://phk.freebsd.dk/loran-c/Antenna/

A single AD797 and via 10m of coax directly into an ADC.

Modern capacitor-based ADCs work fine with even very small signals,
many can be run with sub-volt VREF and still be perfectly happy.

There really isn't anything to it...

The only reason I'm not active in VLF any more is that I have to
choose between VLF reception or my robotic lawn-mowers, and with
5000m² of lawn, that is not even a close call.
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jimlux
2018-12-04 23:08:23 UTC
Reply
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Post by Poul-Henning Kamp
--------
Post by Attila Kinali
On Tue, 4 Dec 2018 13:12:48 -0800
I maintain that it's the lack of a cheap RF front end that is the sticky point.
Then you have misunderstood how little you actually need.
I should clarify - "cheap *off-the-shelf* catalog RF front end"

In my old codger-ness with limited free time, I'm just not wild about
wiring up circuits from scratch. And, I like to see other people
duplicate what I've done, so I've tended to move towards "I can buy that
widget for $20-100" kinds of things.

Hence my 4 channel RTL-SDR+beagle phased array.

I'm going to bet that the 8 bit RTL-SDR isn't going to work on 60kHz.


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2018-12-04 23:54:29 UTC
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--------
Post by jimlux
I'm going to bet that the 8 bit RTL-SDR isn't going to work on 60kHz.
I don't know about the RTL-SDR, but 8 bits will get you quite far with
slow moving time signals like WWVB because you can average for minutes
if you want - provided you feed the ADC a good stable clock.
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David G. McGaw
2018-12-05 04:09:07 UTC
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Actually, an RTL-SDR can because there is direct access to the ADC
available by soldering to internal pads:
www.rtl-sdr.com/rtl-sdr-direct-sampling-mode/  That will give you 8-bit,
14.4Msps.

But as has also been said, a good sound card sampling 24 bits at 192kHz
can be used.

David N1HAC
Post by Poul-Henning Kamp
--------
Post by jimlux
I'm going to bet that the 8 bit RTL-SDR isn't going to work on 60kHz.
I don't know about the RTL-SDR, but 8 bits will get you quite far with
slow moving time signals like WWVB because you can average for minutes
if you want - provided you feed the ADC a good stable clock.
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David G. McGaw
2018-12-05 04:16:52 UTC
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Sorry about that garbled link.  Blame Dartmouth's over-zealous IT. Just
look for "rtl-sdr direct sampling mode" at rtl-sdr dot com.
Post by David G. McGaw
Actually, an RTL-SDR can because there is direct access to the ADC
https://na01.safelinks.protection.outlook.com/?url=www.rtl-sdr.com%2Frtl-sdr-direct-sampling-mode%2F&amp;data=02%7C01%7Cdavid.g.mcgaw%40dartmouth.edu%7C26d18a151e124b336e5008d65a679402%7C995b093648d640e5a31ebf689ec9446f%7C0%7C0%7C636795798255645762&amp;sdata=k7qbMd66xKxoL28CemtFlw5cbhLHMgU01NZlOnfY7Lw%3D&amp;reserved=0  That will give you 8-bit,
14.4Msps.
But as has also been said, a good sound card sampling 24 bits at 192kHz
can be used.
David N1HAC
Post by Poul-Henning Kamp
--------
Post by jimlux
I'm going to bet that the 8 bit RTL-SDR isn't going to work on 60kHz.
I don't know about the RTL-SDR, but 8 bits will get you quite far with
slow moving time signals like WWVB because you can average for minutes
if you want - provided you feed the ADC a good stable clock.
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David G. McGaw
2018-12-05 04:20:06 UTC
Reply
Permalink
Maybe the link came through the list OK?
Post by David G. McGaw
Sorry about that garbled link.  Blame Dartmouth's over-zealous IT. Just
look for "rtl-sdr direct sampling mode" at rtl-sdr dot com.
Post by David G. McGaw
Actually, an RTL-SDR can because there is direct access to the ADC
https://na01.safelinks.protection.outlook.com/?url=www.rtl-sdr.com%2Frtl-sdr-direct-sampling-mode%2F&amp;data=02%7C01%7Cdavid.g.mcgaw%40dartmouth.edu%7C60246767b871406285c808d65a68a8a7%7C995b093648d640e5a31ebf689ec9446f%7C0%7C0%7C636795802882698879&amp;sdata=qu9IZ7jrigjcDqD%2B1d9daSfIHttr3Nn%2Fh0L5mg%2FTsbg%3D&amp;reserved=0  That will give you 8-bit,
14.4Msps.
But as has also been said, a good sound card sampling 24 bits at 192kHz
can be used.
David N1HAC
Post by Poul-Henning Kamp
--------
Post by jimlux
I'm going to bet that the 8 bit RTL-SDR isn't going to work on 60kHz.
I don't know about the RTL-SDR, but 8 bits will get you quite far with
slow moving time signals like WWVB because you can average for minutes
if you want - provided you feed the ADC a good stable clock.
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jimlux
2018-12-05 04:24:05 UTC
Reply
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Post by David G. McGaw
Actually, an RTL-SDR can because there is direct access to the ADC
www.rtl-sdr.com/rtl-sdr-direct-sampling-mode/  That will give you 8-bit,
14.4Msps.
I'm not sure a 8bit ADC gives enough dynamic range, even after
downconversion.
The RTL-SDR is a pretty noisy receiver, too.
Post by David G. McGaw
But as has also been said, a good sound card sampling 24 bits at 192kHz
can be used.
David N1HAC
Post by Poul-Henning Kamp
--------
Post by jimlux
I'm going to bet that the 8 bit RTL-SDR isn't going to work on 60kHz.
I don't know about the RTL-SDR, but 8 bits will get you quite far with
slow moving time signals like WWVB because you can average for minutes
if you want - provided you feed the ADC a good stable clock.
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Alex Pummer
2018-12-05 18:49:38 UTC
Reply
Permalink
There is a problem with most pre-amplifiers and also particularly with
anything up font of the sampling; to get  good data the amplitude of the
sampled signal has to have relative high levels, comparable to
microphone output level -- up to 50mV -- if one wanted to use the sound
cart input. Additionally to that the sound card has it's internal
amplifier before the A to D converter. Unfortunately the "vicinity" of
the 60kHz is not a quite area, but it is full with noise of house hold
and industrial origin. I spent substantial time to investigate that
noises and I found many unsuspected sources. I may own household I have
on tooth cleaning jet for every day use, which was replaced recently wit
a new one since the previous one was more than fifteen years old and
started to show old age problems. The new unit looking from the outside
was very similar to the old one except that the old had one AC motor the
new one has a DC motor with a switching mode power supply, which is with
the motor's commutator generating RF noise up to the TV bands disturbing
the reception and of course generating enough interference to overload
any sound card with pre -amplifier. I am very curious how did they get
that device -- the water jet-- trough the FCC test  or did not ever
border to do it? But that water jet  is not alone, just look your own
computer's including it's power supply. You no not need any very
sophisticated instrument just some old spectrum analyzer, which is
running on it's own without any computer connection, and you will what
is out there, sweep so between 35kHz to 100kHz use one coils as antenna
with a diameter of 2' to 3' and at least thirty turns. With that set up
you will be able to see WWVB to. If you turn the coil's axis
perpendicular to the direction from your position to Forth Collins in
Colorado, you will see the --AM also-- modulated WWVB at 60kHz. These
illegal carriers with very large amplitude are able to overload the
input of the sound card's -- or any other --A to D converter. The old
WWVB receivers for the at the time just AM modulated signal used to use
crystal filter for good reason, which is not usable any more since the
frequency spreading of the phase modulation will not fit into the
crystal filter's band width, and the settling time of the filter's
output will cause one additional AM modulation.   By using some
selection and very linear amplification I was able to get did I get a
120mVp_p signal from WWVB and compared it's phase stability  to the
phase of one other 60kHz signal derived from a GPS receiver with one
u-blox board. If there is interest  I could describe how did I do it.

73

KJ6UHN

Alex
Post by David G. McGaw
Actually, an RTL-SDR can because there is direct access to the ADC
www.rtl-sdr.com/rtl-sdr-direct-sampling-mode/  That will give you 8-bit,
14.4Msps.
But as has also been said, a good sound card sampling 24 bits at 192kHz
can be used.
David N1HAC
Post by Poul-Henning Kamp
--------
Post by jimlux
I'm going to bet that the 8 bit RTL-SDR isn't going to work on 60kHz.
I don't know about the RTL-SDR, but 8 bits will get you quite far with
slow moving time signals like WWVB because you can average for minutes
if you want - provided you feed the ADC a good stable clock.
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Bob kb8tq
2018-12-05 19:47:59 UTC
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Hi

The “good sound card” in this case is indeed not quite as easy to find
as one might think. Most people playing with audio rarely are concerned
once you get past 20KHz or so. Finding a card that stays quiet past
40 KHz can be tough. Even on a 192 KHz card, one can find anti-alias
filters cutting in way before the hoped for ~90 KHz passband is reached.

Bob
There is a problem with most pre-amplifiers and also particularly with anything up font of the sampling; to get good data the amplitude of the sampled signal has to have relative high levels, comparable to microphone output level -- up to 50mV -- if one wanted to use the sound cart input. Additionally to that the sound card has it's internal amplifier before the A to D converter. Unfortunately the "vicinity" of the 60kHz is not a quite area, but it is full with noise of house hold and industrial origin. I spent substantial time to investigate that noises and I found many unsuspected sources. I may own household I have on tooth cleaning jet for every day use, which was replaced recently wit a new one since the previous one was more than fifteen years old and started to show old age problems. The new unit looking from the outside was very similar to the old one except that the old had one AC motor the new one has a DC motor with a switching mode power supply, which is with the motor's commutator generating RF noise up to the TV bands disturbing the reception and of course generating enough interference to overload any sound card with pre -amplifier. I am very curious how did they get that device -- the water jet-- trough the FCC test or did not ever border to do it? But that water jet is not alone, just look your own computer's including it's power supply. You no not need any very sophisticated instrument just some old spectrum analyzer, which is running on it's own without any computer connection, and you will what is out there, sweep so between 35kHz to 100kHz use one coils as antenna with a diameter of 2' to 3' and at least thirty turns. With that set up you will be able to see WWVB to. If you turn the coil's axis perpendicular to the direction from your position to Forth Collins in Colorado, you will see the --AM also-- modulated WWVB at 60kHz. These illegal carriers with very large amplitude are able to overload the input of the sound card's -- or any other --A to D converter. The old WWVB receivers for the at the time just AM modulated signal used to use crystal filter for good reason, which is not usable any more since the frequency spreading of the phase modulation will not fit into the crystal filter's band width, and the settling time of the filter's output will cause one additional AM modulation. By using some selection and very linear amplification I was able to get did I get a 120mVp_p signal from WWVB and compared it's phase stability to the phase of one other 60kHz signal derived from a GPS receiver with one u-blox board. If there is interest I could describe how did I do it.
73
KJ6UHN
Alex
Post by David G. McGaw
Actually, an RTL-SDR can because there is direct access to the ADC
www.rtl-sdr.com/rtl-sdr-direct-sampling-mode/ That will give you 8-bit,
14.4Msps.
But as has also been said, a good sound card sampling 24 bits at 192kHz
can be used.
David N1HAC
Post by Poul-Henning Kamp
--------
Post by jimlux
I'm going to bet that the 8 bit RTL-SDR isn't going to work on 60kHz.
I don't know about the RTL-SDR, but 8 bits will get you quite far with
slow moving time signals like WWVB because you can average for minutes
if you want - provided you feed the ADC a good stable clock.
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Iain Young
2018-12-05 00:04:26 UTC
Reply
Permalink
Post by jimlux
Post by Poul-Henning Kamp
--------
Post by Attila Kinali
On Tue, 4 Dec 2018 13:12:48 -0800
I maintain that it's the lack of a cheap RF front end that is the sticky point.
Then you have misunderstood how little you actually need.
I should clarify - "cheap *off-the-shelf* catalog RF front end"
In my old codger-ness with limited free time, I'm just not wild about
wiring up circuits from scratch.  And, I like to see other people
duplicate what I've done, so I've tended to move towards "I can buy that
widget for $20-100" kinds of things.
Hence my 4 channel RTL-SDR+beagle phased array.
I'm going to bet that the 8 bit RTL-SDR isn't going to work on 60kHz.
Probably not - Even the Funcube dongle down that low doesn't pick up
MSF from here in the UK, and at 66kHz I get BBC Radio 4 (198/3=66..)

However, my main SDR PC has a 192kHz soundcard. Feed that with my
LF active antenna, and MSF, DCF, amongst others come booming in.

Don't discount an active antenna plus a soundcard or ADC that will
sample 192kHz


Iain

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W7SLS
2018-12-05 02:08:59 UTC
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Hello,

Great discussion on this and other topics here.

Just looked up the specs for the SDRPlay RSP2:
1 kHz to 2 GHz.
Should be fine for 60 kHz.

Now to look closer at previous posts for 60 kHz antennas, how to get raw data out of the RSP2 (other than pretty pictures), and see where it fits on the project list.

Regards,
Scott W7SLS
Post by Iain Young
Post by jimlux
Post by Poul-Henning Kamp
--------
Post by Attila Kinali
On Tue, 4 Dec 2018 13:12:48 -0800
I maintain that it's the lack of a cheap RF front end that is the sticky point.
Then you have misunderstood how little you actually need.
I should clarify - "cheap *off-the-shelf* catalog RF front end"
In my old codger-ness with limited free time, I'm just not wild about wiring up circuits from scratch. And, I like to see other people duplicate what I've done, so I've tended to move towards "I can buy that widget for $20-100" kinds of things.
Hence my 4 channel RTL-SDR+beagle phased array.
I'm going to bet that the 8 bit RTL-SDR isn't going to work on 60kHz.
Probably not - Even the Funcube dongle down that low doesn't pick up
MSF from here in the UK, and at 66kHz I get BBC Radio 4 (198/3=66..)
However, my main SDR PC has a 192kHz soundcard. Feed that with my
LF active antenna, and MSF, DCF, amongst others come booming in.
Don't discount an active antenna plus a soundcard or ADC that will
sample 192kHz
Iain
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David G. McGaw
2018-12-05 04:13:58 UTC
Reply
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Any of the RSPs from SDRPlay will cover it and they are great units,
starting at $109 US.  I am literally using an RSP1A right now.

David N1AHC
Post by W7SLS
Hello,
Great discussion on this and other topics here.
1 kHz to 2 GHz.
Should be fine for 60 kHz.
Now to look closer at previous posts for 60 kHz antennas, how to get raw data out of the RSP2 (other than pretty pictures), and see where it fits on the project list.
Regards,
Scott W7SLS
Post by Iain Young
Post by jimlux
Post by Poul-Henning Kamp
--------
Post by Attila Kinali
On Tue, 4 Dec 2018 13:12:48 -0800
I maintain that it's the lack of a cheap RF front end that is the sticky point.
Then you have misunderstood how little you actually need.
I should clarify - "cheap *off-the-shelf* catalog RF front end"
In my old codger-ness with limited free time, I'm just not wild about wiring up circuits from scratch. And, I like to see other people duplicate what I've done, so I've tended to move towards "I can buy that widget for $20-100" kinds of things.
Hence my 4 channel RTL-SDR+beagle phased array.
I'm going to bet that the 8 bit RTL-SDR isn't going to work on 60kHz.
Probably not - Even the Funcube dongle down that low doesn't pick up
MSF from here in the UK, and at 66kHz I get BBC Radio 4 (198/3=66..)
However, my main SDR PC has a 192kHz soundcard. Feed that with my
LF active antenna, and MSF, DCF, amongst others come booming in.
Don't discount an active antenna plus a soundcard or ADC that will
sample 192kHz
Iain
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Bob kb8tq
2018-12-04 21:29:39 UTC
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Hi

So, backing off a bit:

Assuming you are going to compare two data points a bit over 24 hours apart (100,000 seconds):

Accuracy of reading pair Result pp Result sci

100 ms 1 ppm 1x10^-6
10 ms 100 ppb 1x10^-7
1 ms 10 ppb 1x10^-8
100 us 1 ppb 1x10^-9
10 us 100 ppt 1x10^-10
1 us 10 ppt 1x10^-11

At 100 ms, you need to go for a *lot* of days before you get out of the “that’s interesting ….. yawn …”
category. Since it’s a pair you are concerned about, each might have a 50 ms error to get you to the
100 ms total. It’s still plenty good enough for a typical wall clock.

At one day you don’t cross into “as good as a free running Rb” territory until you get below 100 us.
That’s also the point you hit roughly the typical GPS module’s performance at 1 second.
If you want to get a “Time Nuts” grade solution, microseconds are indeed the units to worry about.

Assuming you hit can 100 us per pair, and want to get into the 1 to 10 ppt range, you are out around
100 days for each “run”. That seems like a long time to wait.

Since one period is 16.667 us, hitting well below 100 us implies keeping track of which cycle is which. Getting
to 10 us is just above a 180 degree phase error and 1 us is still above 10 degrees.

I’d say that for a practical “Time Nut" device … you need the equivalent of cycle tracking at the very least.

Indeed, as mentioned by … somebody …. this all can be done and … ummm …. has been done for similar
signals by …errr …somebody :)

Bob
Post by David G. McGaw
That is the specified jitter. They have also said in communications that it has about 50mS resolution. That is as close as they are willing to say a system can be synchronized with it. Perhaps someone will discover a clever way to enhance that.
BTW, I have been told it has also been successfully tested for lock in Brazil. Is there anyone in Australia want to give it a try? Perth is almost directly opposite Fort Collins. :-)
David N1HAC
As was said, IRQ delay is +/-100 mS from the second edge, hardly what a
Time-Nut is looking for.
There is no problem with a delay as long as it is constant. If I know what it
is, then I can correct for it.
The problem is the noise/jitter on the delay. I'm sure somebody will have
data soon.
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Poul-Henning Kamp
2018-12-04 21:38:03 UTC
Reply
Permalink
--------
Post by Bob kb8tq
If you want to get a “Time Nuts” grade solution, microseconds are indeed the units to worry about.
One of the reasons why I play with VLF is to have a sanity-check on GPS, and depending on your application
even +/- 100msec can be sufficient there.

But for anything more than that, you *have* to get hold of the carrier and not just the modulation.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
***@FreeBSD.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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Attila Kinali
2018-12-04 21:21:00 UTC
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Moin,

On Mon, 3 Dec 2018 18:11:30 -0800
Post by Tom Van Baak
https://universal-solder.ca/product/everset-es100-cob-wwvb-60khz-bpsk-receiver-kit-with-2-antennas/
Note it includes the antenna(s). Also has links to documentation.
As this is becoming a topic again, and the EverSet people still
claim that the BPSK modulation of WWVB makes it more resilient
to jamming and easier to receive, I would like to restate
what I've written some years ago [1,2]:

BPSK by itself does not improve timing. At most it improves reception
by having a constant power envelope. But in case of WWVB, where
the AM modulation is still kept, this is not the case. The phase
changes do not help reception at all. In order to help reception,
one needs to send a _known_ bit string in order for a corrolator
in the receiver to pick the signal out of the noise. The only
known bits in the BPSK signal are the first 12 bits of each minute.
Compare this to DCF77 which encodes 512 bits every _second_.
Ie while DCF77 gets something like 10-20dB easier to pick out
of noise, but when using BPSK, WWVB gets... uhmm.. zero improvement.

All the BPSK modulation of WWVB does is
1) Make the signal unusable for any carrier phase tracking receiver
2) Add a second type of bit stream onto the signal for additional
information to be encoded
3) Generate a revenue stream for companies who sell new WWVB receivers.

For more information, read [2]

Attila Kinali

[1] https://www.febo.com/pipermail/time-nuts/2013-July/060456.html
[2] https://www.febo.com/pipermail/time-nuts/2013-July/060471.html
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throw DARK chocolate at you.

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Gregory Maxwell
2018-12-04 21:42:41 UTC
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Post by Attila Kinali
known bits in the BPSK signal are the first 12 bits of each minute.
This seems transparently incorrect to me. If your receiver has access
to only a tiny chunk of signal and no idea of anything else then yes,
but that isn't a realistic restriction. Given that we know the signal
is a clock all the bits are almost perfectly predictable. Unless I'm
confused about something about the signal.

The result is that you have some additional delay in learning the
carrier phase-- since an optimal decoder will make use of both past
and future signal to predict the bitstream, but that isn't really any
challenge against the PLL time constants that would be used.

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Attila Kinali
2018-12-05 13:55:00 UTC
Reply
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On Tue, 4 Dec 2018 21:42:41 +0000
Post by Gregory Maxwell
Post by Attila Kinali
known bits in the BPSK signal are the first 12 bits of each minute.
This seems transparently incorrect to me. If your receiver has access
to only a tiny chunk of signal and no idea of anything else then yes,
but that isn't a realistic restriction. Given that we know the signal
is a clock all the bits are almost perfectly predictable. Unless I'm
confused about something about the signal.
Yes. True. Once you aquired the signal you can guess quite a few bits
of the next minute. But this gives at best 60 bits per minute of
information for the BPSK correlator. Compare this to 512 bits per _second_
of DCF77. Ie DCF77 has 500 times more information to work with and
to pull the signal out of the noise than WWVB.

Or to put it differently: you could say the same for the AM signal.
Once you know what bits will be transmitted, you can do a matched filter
and get an increase in signal quality. Of course, AM is not as easy to
use this technique on and the gain is less, but at these low rates,
it's basically identical.

As I explained in one of the mails I linked to, the reason why BPSK
helps with getting signal out of the noise is the pseudo-random signal
modulated ontop of it, that gives _a_lot_ of additional information
to the signal and de-correlates it from the usual jammers (single frequency
narrow band and wide-band noise-like jammers)[1]. The WWVB does not do
that. The additional spreading of the spectrum of the signal is minimal
and in the order of the spreading due to the AM modulation.

Attila Kinali


[1] This is not tied to BPSK as modulation, but works with
any modulation. The key point here is making the spectrum wide
and predictable. See https://en.wikipedia.org/wiki/Spread_spectrum
--
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the prosperity and technological sophistication in the world is of no
use without that foundation.
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Bob kb8tq
2018-12-04 21:43:57 UTC
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Hi

Again to re-go over what has been said in the past:

Unless they start filling the “extra” bits on the WWVB signal with something
(are they doing this ????) the whole modulation pattern is predictable. Once
you know what time it is “now” what happens from then on can all be calculated.
I believe TVB has already done this part of it.

A “proper” receiver might take the AM and PM modulation signals and generate
an “expected” signal from them once the time now is known. Correlating against
that signal would seem to be the way to get this done.

The one thing the Everest chips do indeed do is demonstrate that initial signal
acquisition can be done under really awful conditions. Getting the same info off
of WWVB with AM only …. not so much ….At least not so much with a receiver
chip that is out on the market.

Bob
Post by Attila Kinali
Moin,
On Mon, 3 Dec 2018 18:11:30 -0800
Post by Tom Van Baak
https://universal-solder.ca/product/everset-es100-cob-wwvb-60khz-bpsk-receiver-kit-with-2-antennas/
Note it includes the antenna(s). Also has links to documentation.
As this is becoming a topic again, and the EverSet people still
claim that the BPSK modulation of WWVB makes it more resilient
to jamming and easier to receive, I would like to restate
BPSK by itself does not improve timing. At most it improves reception
by having a constant power envelope. But in case of WWVB, where
the AM modulation is still kept, this is not the case. The phase
changes do not help reception at all. In order to help reception,
one needs to send a _known_ bit string in order for a corrolator
in the receiver to pick the signal out of the noise. The only
known bits in the BPSK signal are the first 12 bits of each minute.
Compare this to DCF77 which encodes 512 bits every _second_.
Ie while DCF77 gets something like 10-20dB easier to pick out
of noise, but when using BPSK, WWVB gets... uhmm.. zero improvement.
All the BPSK modulation of WWVB does is
1) Make the signal unusable for any carrier phase tracking receiver
2) Add a second type of bit stream onto the signal for additional
information to be encoded
3) Generate a revenue stream for companies who sell new WWVB receivers.
For more information, read [2]
Attila Kinali
[1] https://www.febo.com/pipermail/time-nuts/2013-July/060456.html
[2] https://www.febo.com/pipermail/time-nuts/2013-July/060471.html
--
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throw DARK chocolate at you.
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Attila Kinali
2018-12-05 13:56:56 UTC
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Hi Bob,

On Tue, 4 Dec 2018 16:43:57 -0500
Post by Bob kb8tq
The one thing the Everest chips do indeed do is demonstrate that initial signal
acquisition can be done under really awful conditions. Getting the same info off
of WWVB with AM only …. not so much ….At least not so much with a receiver
chip that is out on the market.
I have not seen any measurement/demonstration of this property yet.
And my back of the envelope calculations showed that BPSK modulation
shouldn't give any substantial gain. Do you have any references where
I could read up on this aquisition gain?

Attila Kinali
--
It is upon moral qualities that a society is ultimately founded. All
the prosperity and technological sophistication in the world is of no
use without that foundation.
-- Miss Matheson, The Diamond Age, Neal Stephenson

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Bob kb8tq
2018-12-05 14:34:46 UTC
Reply
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Hi

There have been several posts in this thread documenting some pretty
amazing performance for the chip. The wall clock I have here (with
what I assume is the same chip) does *way* better than anything I’ve
had before.

Bob
Post by Attila Kinali
Hi Bob,
On Tue, 4 Dec 2018 16:43:57 -0500
Post by Bob kb8tq
The one thing the Everest chips do indeed do is demonstrate that initial signal
acquisition can be done under really awful conditions. Getting the same info off
of WWVB with AM only …. not so much ….At least not so much with a receiver
chip that is out on the market.
I have not seen any measurement/demonstration of this property yet.
And my back of the envelope calculations showed that BPSK modulation
shouldn't give any substantial gain. Do you have any references where
I could read up on this aquisition gain?
Attila Kinali
--
It is upon moral qualities that a society is ultimately founded. All
the prosperity and technological sophistication in the world is of no
use without that foundation.
-- Miss Matheson, The Diamond Age, Neal Stephenson
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Graham / KE9H
2018-12-05 15:27:21 UTC
Reply
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I also ordered one of the EverSet Dev Boards.
Pricey for a one IC "glop-top" package, but I would like to see how it
performs.
But, I could not duplicate quantity one for the price, either.
I also note that they sold out about mid day yesterday, so Tom's
announcement cleaned them out.

As far as the claimed 20 (ish) dB gain of the BPSK modulation scheme, if
you read the papers, it is a system gain, not just a gain from BPSK
modulation, involving error correcting coding and extended correlation
across six minute sequences.

--- Graham
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Poul-Henning Kamp
2018-12-04 22:56:54 UTC
Reply
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--------
Post by Attila Kinali
BPSK by itself does not improve timing. At most it improves reception
by having a constant power envelope. But in case of WWVB, where
the AM modulation is still kept, this is not the case. The phase
changes do not help reception at all. In order to help reception,
one needs to send a _known_ bit string in order for a corrolator
in the receiver to pick the signal out of the noise.
They do that in the "long" sequence, read their spec.

The fact that it is one out of 100-some known sequences does not
significantly change that situation.

And the BPSK does improve timing.

If you have access to, and tracks the carrier, you can nail the
timing all the way down to 1/your_sample_rate.

Been there, done that with DCF77 no big deal.

Even the weird phase-modulation of RDF and BBC on 198kHz can be
nailed down very precisely that way.

But the crucial thing is: You need to digitize the carrier.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
***@FreeBSD.ORG | TCP/IP since RFC 956
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Attila Kinali
2018-12-05 14:09:43 UTC
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Hey Poul-Henning!

On Tue, 04 Dec 2018 22:56:54 +0000
Post by Poul-Henning Kamp
And the BPSK does improve timing.
If you have access to, and tracks the carrier, you can nail the
timing all the way down to 1/your_sample_rate.
Yes, but the same is true for pure AM modulation. If you sample
and track the carrier digitally, then you get quite a bit of
processing gain due to the long integration time. My point is that
the WWVB BPSK modulation does not give (much of) an advantage
over the AM modulation because the amount of known information
is so low.... That is, unless I miss something and there is actually
an advantage that can be exploited.

Attila Kinali
--
It is upon moral qualities that a society is ultimately founded. All
the prosperity and technological sophistication in the world is of no
use without that foundation.
-- Miss Matheson, The Diamond Age, Neal Stephenson

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Poul-Henning Kamp
2018-12-05 15:24:24 UTC
Reply
Permalink
--------
Post by Attila Kinali
On Tue, 04 Dec 2018 22:56:54 +0000
Post by Poul-Henning Kamp
And the BPSK does improve timing.
If you have access to, and tracks the carrier, you can nail the
timing all the way down to 1/your_sample_rate.
Yes, but the same is true for pure AM modulation.
No, it is not, because the AM modulation is subject to
the very narrow bandwidth of the transmission antenna which
smears the flank out over several carrier cycles.

The BPSK phase reversal is not smeared out the same way.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
***@FreeBSD.ORG | TCP/IP since RFC 956
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Never attribute to malice what can adequately be explained by incompetence.

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John Moran, Scawby Design
2018-12-04 22:28:30 UTC
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I'm a little puzzled as to why people keep calling 60kHz - 'RF'. Many Hi-Fi audio amplifiers go higher than that.

As for an 'RF' front end, there are dozens of off-the-shelf op-amps that can amplify the signal from a tuned ferrite rod aerial sufficiently to then feed into a decent A-D and then a micro.

Analog Devices have A-Ds that digitize the carrier of 12GHz RF signals so I think we should be able to manage 60kHz ... the problem then being to process the resulting data stream.

However, fast A-Ds are not particularly cheap and you would need circa 50MHz sample rate to resolve 1deg of the carrier, and TVB has already stated that there are no time benefits to BPSK, so this is all just an interesting technical exercise, isn't it?

John Moran
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Poul-Henning Kamp
2018-12-04 23:03:19 UTC
Reply
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--------
Post by John Moran, Scawby Design
However, fast A-Ds are not particularly cheap and you would need
circa 50MHz sample rate to resolve 1deg of the carrier, and TVB has
already stated that there are no time benefits to BPSK, so this is
all just an interesting technical exercise, isn't it?
I admit it would be interesting to do the allan variance on it,
but measuring the carrier to 1 degree in every single cycle is
waaaaay overkill.

1 MHz sampling rate is fine, but go for 5 or 10 MHz so you can
drive the ADC directly from your house-standard.

And BPSK *does* improve the timing, because you can very precisely
measure when the change of phase happens, and it since it happens
at a carrier zero-crossing you can filter it down to +/- sample.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
***@FreeBSD.ORG | TCP/IP since RFC 956
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Poul-Henning Kamp
2018-12-05 08:02:38 UTC
Reply
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--------
I think I will get distracted over Christmas sketching out some designs ...
Grab som I+Q samples from a kiwisdr somewhere and start playing with
signals instead.

If you like it, start making hardware.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
***@FreeBSD.ORG | TCP/IP since RFC 956
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jimlux
2018-12-04 23:04:52 UTC
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Post by John Moran, Scawby Design
I'm a little puzzled as to why people keep calling 60kHz - 'RF'. Many Hi-Fi audio amplifiers go higher than that.
As for an 'RF' front end, there are dozens of off-the-shelf op-amps that can amplify the signal from a tuned ferrite rod aerial sufficiently to then feed into a decent A-D and then a micro.
yes, and someone has to pick one of them and put it on a board, with a
voltage regulator and other parts.

It's not complex, but it's also not something you can buy off the shelf,
plug into your RPi and start coding up the filter.
Post by John Moran, Scawby Design
Analog Devices have A-Ds that digitize the carrier of 12GHz RF signals so I think we should be able to manage 60kHz ... the problem then being to process the resulting data stream.
I don't think the ADC is the challenge - a decent tuned front end with
some gain so that the signal is around a volt, and you can feed the
onchip ADC of most microcontrollers and you'll be all set.

If you had a wide open front end, with AM broadcast, all manner of RFI,
and so forth, you'd probably need more bits. But a few kHz sample rate
would probably work, if your sample and hold was good - if it isn't then
maybe a couple hundred kHz sample rate.

Easy to do with most microcontrollers on an off the shelf board.
Post by John Moran, Scawby Design
However, fast A-Ds are not particularly cheap and you would need circa 50MHz sample rate to resolve 1deg of the carrier, and TVB has already stated that there are no time benefits to BPSK, so this is all just an interesting technical exercise, isn't it?
Your sample rate doesn't have to be anywhere near the resolution - what
you do is fit a sine wave to the samples you have and you can easily get
sub-sample accuracy. The important thing is the SNR. Higher sample
rates do help, because they basically give you that Sqrt(N) improvement
in SNR over a single sample.


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gandalfg8--- via time-nuts
2018-12-05 09:15:52 UTC
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I feel guilty now:-)
Obviously MSF is strong up here but I was able to receive it from Rugby when I first moved north using a directional LF antenna and was under the impression coverage was still ok throughout the UK, although it seems I was wrong on that.

The French station is TDF transmitted from Allouis on 162KHz.It previously also carried an AM broadcast station, although that was shut down some time ago which simplifies things a bit, and it comes in here at a similar level to MSF as it's much higher power to start with.

Don't rule out Droitwich on 198KHz though, that's rubidium rather than caesium controlled but still very useful as an off air reference.There's a bit of a traceability issue up here due to the use of local repeaters but I still keep a Halcyon PFS1 as a backup and for the built in DDS.
Nigel GM8PZR

Hi Nigel

I moved from Warwickshire to west Sussex  south of the downs 20 years ago
and all was OK But since it moved I have not bean able to use the 60 Khz
reference  I am thinking of setting up a reference to use the one in France
I think it is 192 Khz
And then I can do a frequency difference between the 2
Also Looking for a rabid

Best regards Paul
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Poul-Henning Kamp
2018-12-05 09:32:22 UTC
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--------

Try this:

https://sdr.hu/

Pick a european receiver, most of them have antennas that
will do VLF, otherwise pick another.

Enter 162 KHz

Press the two arrows pointing towards each other, twice

Pick extension "iq_display"

Change from "density" to "points"

Click on "160"

See live phase modulation

Change frequency to 198 kHz

Change frequency to 77.5 kHz

...

Then, if you want to really play:

https://github.com/hcab14/kiwiclient

allows you to capture and save the raw IQ data.

If necessary read:

https://www.dspguide.com/

Now, stop talking and start coding :-)
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
***@FreeBSD.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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ew via time-nuts
2018-12-05 12:48:21 UTC
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It just took me four days for three year old  LACross clock in Florida to sync up after battery change                     Bert Kehren
In a message dated 12/4/2018 4:22:17 PM Eastern Standard Time, ***@kinali.ch writes:

Moin,

On Mon, 3 Dec 2018 18:11:30 -0800
Post by Tom Van Baak
https://universal-solder.ca/product/everset-es100-cob-wwvb-60khz-bpsk-receiver-kit-with-2-antennas/
Note it includes the antenna(s). Also has links to documentation.
As this is becoming a topic again, and the EverSet people still
claim that the BPSK modulation of WWVB makes it more resilient
to jamming and easier to receive, I would like to restate
what I've written some years ago [1,2]:

BPSK by itself does not improve timing. At most it improves reception
by having a constant power envelope. But in case of WWVB, where
the AM modulation is still kept, this is not the case. The phase
changes do not help reception at all. In order to help reception,
one needs to send a _known_ bit string in order for a corrolator
in the receiver to pick the signal out of the noise. The only
known bits in the BPSK signal are the first 12 bits of each minute.
Compare this to DCF77 which encodes 512 bits every _second_.
Ie while DCF77 gets something like 10-20dB  easier to pick out
of noise, but when using BPSK, WWVB gets... uhmm..  zero improvement.

All the BPSK modulation of WWVB does is
1) Make the signal unusable for any carrier phase tracking receiver
2) Add a second type of bit stream onto the signal for additional
  information to be encoded
3) Generate a revenue stream for companies who sell new WWVB receivers.

For more information, read [2]

            Attila Kinali

[1] https://www.febo.com/pipermail/time-nuts/2013-July/060456.html
[2] https://www.febo.com/pipermail/time-nuts/2013-July/060471.html
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                throw DARK chocolate at you.

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UNIVERSAL-SOLDERR Canada
2018-12-07 17:59:52 UTC
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I want to say some things about the ES100 development kits we offer in our
Universal-Solder online store.



First of all, please keep in mind that the entire development was done to
fix reception issues with the older AM standard. When the WWV stations were
installed, there wasn't a remarkable amount of "electro smog" those days,
and the reception was probably more related to the length of your loopstick.
Today we have a completely different situation, and standard "atomic clocks"
pick up noise from so many devices like your phone charger, your flat
screen, or even your 120V LED light bulbs, but are because of a lack on
digital processing and filtering hardly capable of finding the amplitude
shift in the noise floor. And this is, where BPSK comes to play, and what it
was developed for: For a new generation of "atomic clocks" with substantial
better reception in difficult or noisy environment, and within buildings.



This said, WWVB BPSK is not meant to be more precisely than the AM standard,
and in my opinion it can't even be, since there is digital signal processing
and data transmission protocols involved. But who cares, when the second
hand on a wall clock is 50ms behind? I actually hope the time error, caused
by the function of the microcontroller and data communication, is better
predictable, and time-nuts will figure out how to predict it.



Some of you heard about the other chip, the ES200, since it was reviewed
somewhere a while ago. But there is actually no plan I would know about, to
have these chips manufactured.



Finally, I want you to understand, that WWVB BPSK and the ES100 chip is
still a low volume product, but with a multi-million development effort. And
what we sell is a development kit, not a Chinese mass product. The price
will most likely drop over the time, but a special deal with La Crosse, to
make an affordable wall clock happen, can't by no means be the reference
price for such a development kit. In the price of 68.50 CAD (roughly 52 USD)
is also shipping included, which is not less than a minimum of 10 CAD to
destinations in the US, where most of the kits go. But this is part of our
shipping policy, to offer free shipping when the order value is over 30
bucks, and is not limited to the ES100 kits.



The said above is my personal opinion, and neither influenced by, nor
concerted with EverSet Technologies.



Volker Forster

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