GPS antenna in silicon/RTV encapsulation

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

Am experimenting with small low cost GPS antennas and am considering as an
alternative RTV/silicon. Any information on RF attenuation of RTV/silicon
at 1.6 GHz ?
Bert Kehren

[Jim Lux]

Post by E***@public.gmane.org
Am experimenting with small low cost GPS antennas and am considering as an
alternative RTV/silicon. Any information on RF attenuation of RTV/silicon
at 1.6 GHz ?

Are you potting the antenna in a solid mass of silicone? Or using it to
seal an enclosure or what?

pure silicone is very low loss, and it probably has an epsilon around 3.
It can be loaded with silica (which is also low loss) to adjust the
mechanical properties and electrical properties. It can also be loaded
with other things (TiO2) which will increase the epsilon, but also the
loss.

the plastics that are notorious for loss are ones that have metal or
carbon loading or that are hygroscopic so they pick up water.

In the clear plastics world, Polypropylene, polyethylene and polystrene
are pretty good. Polycarbonate isn't as good, neither are various
acetals (Delrin) and acetates

Here's a chart
http://www.rfcafe.com/references/electrical/dielectric-constants-strengths.htm

or another chart
http://www.eccosorb.com/Collateral/Documents/English-US/dielectric-chart.pdf

here's a whole report from Dow on silcone rubbers as dielectrics

http://www.dtic.mil/dtic/tr/fulltext/u2/656331.pdf

They give quite low loss tangents at 10^9 cps (which I looked up on my
cps to Hz conversion chart.. That's in your frequency range) 0.0059 loss
tangent for Silastic 80.

The trick for you will be knowing what else is in your particular
silicone resin, and controlling the water content.

[nuts]

I'd be inclined to look at radome construction.

http://www.mpdigest.com/issue/articles/2008/may/mfg/default.asp

The E-3 AWACS is mostly S-2 glass, but they need the strength. For a
radome sitting outside, you might be able to do better.

The advantage to S-2 glass is you can buy it easily, especially if you
have a Tap Plastics handy. It works well with the Marine Resin they
sell, so you know it will last a long time outdoors.

You need to cure the resin in a vacuum, though not a particularly good
vacuum. There are probably guides on the internet, but here is the
basic scheme to make a fiberglass composite structure.

Make a form of the final product.

Cover the form in mylar. Tap Plastics sells the mylar too. The resin
won't stick to the mylar.

Cut the cloth to cover the form. Where you overlap, leave at least an
inch. You need both the S-2 glass and the thin fiberglass mat. The mat
is a very loose weave that can hold more resin than the glass.

The basic construction is a sandwich of cloth, mat, then cloth. You can
add more layers, but you always want mat between the cloth, and cloth
on the outside.

You will need more mylar to cover the last layer of cloth. This is to
keep the air out. It helps to have this cut ahead of time because the
resin will be hardening as you work.

Mix the resin with hardener.

Brush the mylar on the form with resin. The resin on the form is needed
to hold the cloth onto it.

Place the cloth on the form. Brush on resin.

Cover with mat. Brush on more resin.

Cover with the final layer. Apply more resin.

Apply the mylar. Use masking tape to keep it attached.

Wait two days.

Note that the form has to be "destructible", that is you need to pull
it away from the radome. Generally you use cardboard.

An alternative scheme, though I don't suggest it for a radome, is to
use a foam core. You can bush directly onto the form. You need to at
least a layer of mat then cloth on both sides of the form. Apply the
mylar and wait two days. The form is part of the final structure, so
there is nothing to remove.

Generally for antennas in radome, all you do is have a "weep" hole at
the bottom the antenna to allow air exchange.

[Jim Lux]

Post by nuts
I'd be inclined to look at radome construction.

http://www.mpdigest.com/issue/articles/2008/may/mfg/default.asp

The E-3 AWACS is mostly S-2 glass, but they need the strength. For a
radome sitting outside, you might be able to do better.

Radome design is considerably more complex than just putting something
over an antenna.

Typically, they make them as two face sheets separated by a honeycomb,
but the dimensions and materials are chosen to minimize the reflection
losses (e.g. the spacing might not be constant in the radome, depending
on the angle of incidence of the radiation). A very thin face sheet is
a tiny fraction of a wavelength, so the reflections from the two
surfaces are almost in the same phase.

For folks like time-nuts interested in parts in 1E15, this kind of thing
makes a difference; not so much because of the attenuation, but because
the reflected waves can cause a small phase shift in the apparent
carrier phase; e.g. a 20dB reflection at 90 degrees shifts the apparent
phase by about arctan(0.9)= 25 degrees.

Typically in a radome, you shoot not only for low loss, but also low
epsilon, so the reflection effects will be less.

Post by nuts
The advantage to S-2 glass is you can buy it easily, especially if you
have a Tap Plastics handy. It works well with the Marine Resin they
sell, so you know it will last a long time outdoors.

What are the dielectric properties of such a composite? There's a
reason why we don't build microwave circuits (in general) on G-10 or
FR-4 material and use more exotic Rogers or Taconic substrates. (there's
other reasons too..)

Typical fiberglass uses an acrylic resin and acrylic has the
spectacularly high loss tangent of 0.02 at only 1 MHz. The glass would
help bring the loss down (since glass has a somewhat lower tangent, and
if you have a fairly "dry" mix with small resin fraction, that helps)

FR-4 has an epsilon of about 5 at low frequencies falling to a bit more
than 4 at GHz frequencies, depending on the glass/epoxy ratio, and a
loss tangent of around 0.01 at 1-2 GHz. This is quite high compared to
sheet plastic of one sort or another.



Take home message: I wouldn't fabricate a radome out of surfboard/boat
building fiberglass unless you are very careful with the EM design.

[nuts]

I don't use the surf board resin. I use

http://www.tapplastics.com/product/fiberglass/polyester_resins/tap_marine_vinyl_ester_resin/34

I don't have specifics on what Tap sells, but vinyl ester resins have a
dielectic coeficient around 4 and dissipation of at least 0.00x. The
resin is actually better than the S-2 glass.I suppose I can ask who
makes their resin, but I don't know if anyone at a store has that
answer.

It works quite well on L-band. But to each his own. It is certainly
better than the thick PVC pipe a lot of home brew antenna makers use.
PVC degrades with UV unless you paint it, and if you paint it, who
knows what the final result will be.

The AWACS has a Al frame. Talk about reflections!

The cheap arse test for a radome is you put it in the microwave with a
bowl of water. See if the material gets hot. The S-2 with vinyl resin
works great in that test.

[Jim Lux]

Post by nuts
I don't use the surf board resin. I use

http://www.tapplastics.com/product/fiberglass/polyester_resins/tap_marine_vinyl_ester_resin/34

I don't have specifics on what Tap sells, but vinyl ester resins have a
dielectic coeficient around 4 and dissipation of at least 0.00x. The
resin is actually better than the S-2 glass.I suppose I can ask who
makes their resin, but I don't know if anyone at a store has that
answer.

ah, but this is "time nuts" and we obsess about the 14th decimal point<grin>

It kind of depends on what you're looking for. For instance, I don't
recall what the big radome over the fancy Leica multiband artichoke
antennas is like. I think it's just plastic (some UV inhibited
plastic), but it might have glass or nomex in it.

The one over the actual elements (inside the choke ring) is some fairly
exotic filled plastic in a carefully designed shape to keep the phase
center in the same place regardless of incidence angle.

1mm phase center shift is 0.005 wavelength (about 2 degrees) of carrier
phase. Over a 8 hour pass (4.3E13 cycles) that's in the 1 part in 1E15
range.

[nuts]

Then again, if you home brew antenna rots due to a poor radome, this is
all for naught. ;-) I hope you read the link I posted since it goes
into rain drops on the radome.

[Chris Albertson]

Radom for a GPS antenna. I used this for a while...

Place your patch type antenna on a small round black of plastic foam
packing material. Make a slit for the antenna cable so that the little
antann lays flat on the disk of foam and the cable comes up from the
bottom. Now find a suitable glass jar. Maybe you have finish some
pickles or whatever. Clean the jar and turn it upside down then force the
jar over the disk of foam.

If you like to mount it to a pole or mast, cut a one inch hole in the jar
lid turn the lid upside down and screw it to the a wood pole (2x4) The jar
with thread onto the lid.

Eventually the lib will rust and the flat bottom jar might not work in your
location but is is completely weather proof for zero cost. I eventually
bought a real timing GPS antenna and paced it on e 1" galvanized pipe mast.
BTW I looked at some expensive GPS antenna mounting hardware intended
to connect an antenna to a pipe and found it was functionally identical to
a pipe flange. An inverted jar lid glued to a pipe flange would make a
great radome, and then you lead the cable down the pipe. Spray paint it
all white and it would even look good.

Post by nuts
I'd be inclined to look at radome construction.

http://www.mpdigest.com/issue/articles/2008/may/mfg/default.asp

The E-3 AWACS is mostly S-2 glass, but they need the strength. For a
radome sitting outside, you might be able to do better.
The advantage to S-2 glass is you can buy it easily, especially if you
have a Tap Plastics handy. It works well with the Marine Resin they
sell, so you know it will last a long time outdoors.
You need to cure the resin in a vacuum, though not a particularly good
vacuum. There are probably guides on the internet, but here is the
basic scheme to make a fiberglass composite structure.
Make a form of the final product.
Cover the form in mylar. Tap Plastics sells the mylar too. The resin
won't stick to the mylar.
Cut the cloth to cover the form. Where you overlap, leave at least an
inch. You need both the S-2 glass and the thin fiberglass mat. The mat
is a very loose weave that can hold more resin than the glass.
The basic construction is a sandwich of cloth, mat, then cloth. You can
add more layers, but you always want mat between the cloth, and cloth
on the outside.
You will need more mylar to cover the last layer of cloth. This is to
keep the air out. It helps to have this cut ahead of time because the
resin will be hardening as you work.
Mix the resin with hardener.
Brush the mylar on the form with resin. The resin on the form is needed
to hold the cloth onto it.
Place the cloth on the form. Brush on resin.
Cover with mat. Brush on more resin.
Cover with the final layer. Apply more resin.
Apply the mylar. Use masking tape to keep it attached.
Wait two days.
Note that the form has to be "destructible", that is you need to pull
it away from the radome. Generally you use cardboard.
An alternative scheme, though I don't suggest it for a radome, is to
use a foam core. You can bush directly onto the form. You need to at
least a layer of mat then cloth on both sides of the form. Apply the
mylar and wait two days. The form is part of the final structure, so
there is nothing to remove.
Generally for antennas in radome, all you do is have a "weep" hole at
the bottom the antenna to allow air exchange.
_______________________________________________
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[Lester Veenstra]

The classic DIY test of material for RF use is give it 60 seconds in a
microwave oven.
If it gets warm, it’s not a good candidate.

The other more typical concern with "RTV" type materials are the ones using
acetic acid to cure. This outgases, condenses with water vapor to form an
corrosive material on the electronics inside a "sealed" environment. When
the unit mails, and you look inside, you find lots of "green" corrosion
inside, to the point interconnects fail. There are electronic friendly forms
of the sealant that do not have the vinegar odor.


Lester B Veenstra  MØYCM K1YCM W8YCM
lester-ZR4laLYtwi+***@public.gmane.org

US Postal Address:
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-----Original Message-----
From: time-nuts-bounces-***@public.gmane.org [mailto:time-nuts-bounces-***@public.gmane.org] On
Behalf Of Jim Lux
Sent: Monday, April 14, 2014 11:32 PM
To: time-nuts-***@public.gmane.org
Subject: Re: [time-nuts] GPS antenna in silicon/RTV encapsulation

Post by E***@public.gmane.org
Am experimenting with small low cost GPS antennas and am considering
as an alternative RTV/silicon. Any information on RF attenuation of
RTV/silicon at 1.6 GHz ?

Are you potting the antenna in a solid mass of silicone? Or using it to seal
an enclosure or what?

pure silicone is very low loss, and it probably has an epsilon around 3.
It can be loaded with silica (which is also low loss) to adjust the
mechanical properties and electrical properties. It can also be loaded
with other things (TiO2) which will increase the epsilon, but also the
loss.

the plastics that are notorious for loss are ones that have metal or carbon
loading or that are hygroscopic so they pick up water.

In the clear plastics world, Polypropylene, polyethylene and polystrene are
pretty good. Polycarbonate isn't as good, neither are various acetals
(Delrin) and acetates

Here's a chart
http://www.rfcafe.com/references/electrical/dielectric-constants-strengths.h
tm

or another chart
http://www.eccosorb.com/Collateral/Documents/English-US/dielectric-chart.pdf

here's a whole report from Dow on silcone rubbers as dielectrics

http://www.dtic.mil/dtic/tr/fulltext/u2/656331.pdf

They give quite low loss tangents at 10^9 cps (which I looked up on my cps
to Hz conversion chart.. That's in your frequency range) 0.0059 loss tangent
for Silastic 80.

The trick for you will be knowing what else is in your particular silicone
resin, and controlling the water content.


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[Jim Lux]

Post by Lester Veenstra
The classic DIY test of material for RF use is give it 60 seconds in a
microwave oven.
If it gets warm, it’s not a good candidate.

that's fine if you're looking for a gross measure of suitability.

If you're concerned about things like dielectric constant or tenths of a
dB, that's probably not as good a test.

That is, getting warm in a microwave is a sign of "certainly not
suitable", but not getting warm is not a sign of suitable.

[Martin VE3OAT]

Bert,
I don't know about 1.6 GHz but I can tell you with some authority that
before RTV/silicone is fully cured it is highly conductive to energy
at 60 Hz.
... Martin VE3OAT

Post by E***@public.gmane.org
Am experimenting with small low cost GPS antennas and am
considering as an alternative RTV/silicon. Any information
on RF attenuation of RTV/silicon at 1.6 GHz ?
Bert Kehren

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

Working off list on a super high performance GPSDO but low cost thanks to a
time nut (sorry forgot his name) he directed me to DX.com which have ublox
with antenna for lwss than $ 23. Super performance and though they are out
of the one with 1 pps all you have to do is solder directly to the module.
Have both versions. Attached you see what I did with the antenna but found
out the hard way that when it rains the concave bottom fills with water,
still works but not as good. So last night I made it flat with 3M Marine
5200 slow cure that I have extensive experience with from boating. Will take a
full week to cure but if it does not work I can always remove it and start
over
Bert Kehren

[Jim Lux]

Post by E***@public.gmane.org
Working off list on a super high performance GPSDO but low cost thanks to a
time nut (sorry forgot his name) he directed me to DX.com which have ublox
with antenna for lwss than $ 23. Super performance and though they are out
of the one with 1 pps all you have to do is solder directly to the module.
Have both versions. Attached you see what I did with the antenna but found
out the hard way that when it rains the concave bottom fills with water,
still works but not as good. So last night I made it flat with 3M Marine
5200 slow cure that I have extensive experience with from boating. Will take a
full week to cure but if it does not work I can always remove it and start
over

There is a similar approach using a small "display dome" which is
basically a round bottom beaker kind of shape designed to go on a wooden
base. It can just as easily go on a big cork or stopper, or a disk cut
out of a HDPE cutting board.


Googling "display dome" will show you copious choices. or somewhere like
"glassdomes.com"

Of course, if you have a supply of canning jars or babyfood jars, then
you can use those. Nothing says the jar has to be mounted with the axis
vertical. You could do it sideways (like a ship in a bottle) to help
solve the "rain in the punt" problem.

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

The Gerber Baby Food Jar at Wall Mart $ 0.49


In a message dated 4/15/2014 1:03:40 P.M. Eastern Daylight Time,

Working off list on a super high performance GPSDO but low cost thanks

to a

time nut (sorry forgot his name) he directed me to DX.com which have

ublox

with antenna for lwss than $ 23. Super performance and though they are

out

of the one with 1 pps all you have to do is solder directly to the

module.

Have both versions. Attached you see what I did with the antenna but

found

out the hard way that when it rains the concave bottom fills with water,
still works but not as good. So last night I made it flat with 3M Marine
5200 slow cure that I have extensive experience with from boating. Will

take a

full week to cure but if it does not work I can always remove it and

start

over

There is a similar approach using a small "display dome" which is
basically a round bottom beaker kind of shape designed to go on a wooden
base. It can just as easily go on a big cork or stopper, or a disk cut
out of a HDPE cutting board.


Googling "display dome" will show you copious choices. or somewhere like
"glassdomes.com"

Of course, if you have a supply of canning jars or babyfood jars, then
you can use those. Nothing says the jar has to be mounted with the axis
vertical. You could do it sideways (like a ship in a bottle) to help
solve the "rain in the punt" problem.


_______________________________________________
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To unsubscribe, go to
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[Jim Lux]

Post by E***@public.gmane.org
The Gerber Baby Food Jar at Wall Mart $ 0.49

Is there a particular kind of food that works best? Perhaps strained
prunes has the best regularity?

[Chris Albertson]

Actually I used a home canning type wide mouth mason jar. I thought
about a fish bowl but there are not threads for mounting. Then I got
smarter and spend $29 on a real timing antenna and it''s been on the roof
for years. The "jar on a stick" works but has very poor WAF.

Post by Jim Lux

Post by E***@public.gmane.org
The Gerber Baby Food Jar at Wall Mart $ 0.49
Is there a particular kind of food that works best? Perhaps strained

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

[Said Jackson]

Guys, someone somehow hacked my address book and has been going through it slowly and sending spam in my name. Please do not open the attachments or links if you get a link from "me".

Sent From iPhone

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

Having five GPSDO's running and some for over 14 years I have a very
sophisticated and expensive antenna system. This is part of a project that with
the disappearance of Tbolts and other commercial GPSDO's to make available
to time nuts state of the art performance at an affordable price,
specifically those that have a hard time justifying large expenditures. To me the fun
is in the challenge and maximum performance at minimum cost is fun. Stay
tuned.
Bert Kehren.


In a message dated 4/15/2014 4:05:38 P.M. Eastern Daylight Time,
albertson.chris-***@public.gmane.org writes:

Actually I used a home canning type wide mouth mason jar. I thought
about a fish bowl but there are not threads for mounting. Then I got
smarter and spend $29 on a real timing antenna and it''s been on the roof
for years. The "jar on a stick" works but has very poor WAF.

The Gerber Baby Food Jar at Wall Mart $ 0.49
Is there a particular kind of food that works best? Perhaps strained

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

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

Washed all three down the sink
Bert Kehren


In a message dated 4/15/2014 3:18:34 P.M. Eastern Daylight Time,

The Gerber Baby Food Jar at Wall Mart $ 0.49

Is there a particular kind of food that works best? Perhaps strained
prunes has the best regularity?


_______________________________________________
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To unsubscribe, go to
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and follow the instructions there.

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

For the group -


Re: [time-nuts] GPS antenna in silicon/RTV encapsula



I have been reading the comments on this for a few days. Here is the scoop - Almost every adhesive known to man is absolute bad news when applied to RF components.

Adhesives are sticky because they consist of "polar molecules" that tend t align with any RF field. Water is a polar molecule and that is why is get hot in a microwave field. So in general, adhesives are very lossy at even low RF frequencies.

There is a subset of the Microwave industry that provides well characterized adhesives to that industry. Special foams have been developed for potting of microwave antennas and even those cause changes in impedance and pattern that the designer must account for.

The parameters you are interested in are the "dielectric constant" which will determine how much the velocity of propagation is reduced in the material, and the "loss tangent" which is the microwave version of the "dissipation factor' often specified for dielectric in capacitors. You want a low dielectric constant and a very low loss tangent - approaching 0. These are not commonly in adhesives. That is
why "Potted" antennas are often potted in a foam consisting of not a lot of adhesive and a lot of low loss gas bubbles.

Google "loss tangent" for more information.

The short answer from this olde microwave engineer - do not try to pot your antenna, it will be rendered inoperative unless you use one of the microwave specified potting materials. Rather provide an air filled enclosure / radome of some very thin walled plastic.

-73 john k6iql






-----Original Message-----
From: time-nuts-request <time-nuts-request-***@public.gmane.org>
To: time-nuts <time-nuts-***@public.gmane.org>
Sent: Fri, Apr 18, 2014 10:00 am
Subject: time-nuts Digest, Vol 117, Issue 66


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Today's Topics:

1. Re: time-nuts Digest, Vol 117, Issue 61 (HagaaarTheHorrible)
2. Re: GPS antenna in silicon/RTV encapsulation (Jim Lux)
3. quartz clock/watch question (Robert Roehrig)
4. Re: time-nuts Digest, Vol 117, Issue 61 (Bob Camp)
5. Re: Measuring the accurcy of a wrist watch (Chris Albertson)


----------------------------------------------------------------------

Message: 1
Date: Fri, 18 Apr 2014 15:17:58 +0200
From: HagaaarTheHorrible <hagaaar587plus7-gM/Ye1E23mwN+***@public.gmane.org>
To: time-nuts-***@public.gmane.org
Subject: Re: [time-nuts] time-nuts Digest, Vol 117, Issue 61
Message-ID: <A14E3790-E838-4043-8344-D371F9B81200-gM/Ye1E23mwN+***@public.gmane.org>
Content-Type: text/plain; charset=us-ascii

Hi Dave and thanks for the quick answer!
My thesis is about a phase noise measurement device I developed, which primary
use is to measure phase noise/jitter of audioband DACs. I probably won't be
focussing on jitter too much but would like to know if there even is one
accepted standard definition.
For example, in the different definitions I found so far, the seperation between
jitter and wander sometimes is given to be at 1Hz, 10Hz and sometimes just mushy
definitions like "very low frequencies"...
I doubt it is that important for my thesis anyway, but I'd really like to know
for myself, so if anyone has a pointer for me it would be greatly appreciated!

Datum: 17. April 2014 11:21:25 MESZ
An: "Discussion of precise time and frequency measurement"
Betreff: Re: [time-nuts] Jitter Definition
Antwort an: Discussion of precise time and frequency measurement
It depends on what your thesis is all about- you could try some of the ITU

documents for 'official' definitions but these may or may not be relevant to
your thesis.

DaveB, NZ
Sent: Thursday, April 17, 2014 2:54 PM
Subject: [time-nuts] Jitter Definition

Hello there,
I tried searching the archives (and google, IEEE, NIST, ITU), but didn't

really find a satisfying answer, so I thought I'd ask directly.

Is there any kind of standard definition for Jitter which is commonly

accepted?

I (think I) understood Jitter and phase noise by now, yet I need to give some

references in my bachelor's thesis, so I'm looking for a definition. So far I
haven't found a real definition of the different "types" (RMS,p2p,c2c,...) and
components(RJ,DJ) of Jitter, but I guess there must be some kind of accepted
standard!?

If anyone could point me to some "official sources" which are "accepted in

the industry", I'd be very grateful.

Thanks in advance and best regards
Hag
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------------------------------

Message: 2
Date: Fri, 18 Apr 2014 06:09:14 -0700
From: Jim Lux <jimlux-***@public.gmane.org>
To: time-nuts-***@public.gmane.org
Subject: Re: [time-nuts] GPS antenna in silicon/RTV encapsulation
Message-ID: <535123FA.1030704-***@public.gmane.org>
Content-Type: text/plain; charset=windows-1252; format=flowed

The classic DIY test of material for RF use is give it 60 seconds in a
microwave oven.
If it gets warm, it?s not a good candidate.

that's fine if you're looking for a gross measure of suitability.

If you're concerned about things like dielectric constant or tenths of a
dB, that's probably not as good a test.

That is, getting warm in a microwave is a sign of "certainly not
suitable", but not getting warm is not a sign of suitable.



------------------------------

Message: 3
Date: Fri, 18 Apr 2014 08:00:01 -0700 (PDT)
From: Robert Roehrig <k9eui-/***@public.gmane.org>
To: timenuts <time-nuts-***@public.gmane.org>
Subject: [time-nuts] quartz clock/watch question
Message-ID:
<1397833201.64991.YahooMailNeo-zpER/x4socO2Y7dhQGSVAJOW+***@public.gmane.org>
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When a quartz watch or clock is assembled, what method is used to get it as
accurate as possible?


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Message: 4
Date: Fri, 18 Apr 2014 10:12:46 -0400
From: Bob Camp <lists-***@public.gmane.org>
To: Discussion of precise time and frequency measurement
<time-nuts-***@public.gmane.org>
Subject: Re: [time-nuts] time-nuts Digest, Vol 117, Issue 61
Message-ID: <E7C598ED-8903-4C55-AB96-ED5875523ECD-***@public.gmane.org>
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Hi

The dividing line between wander and jitter is a ?legal" one rather than a
physics one. It?s a breakpoint in a spec where the treatment of the noise
changes from ?do this? to ?do that?. In most cases you pass wander and you
attenuate jitter. Different specs put the line at different points based on
hoped for system performance.

Bob

Hi Dave and thanks for the quick answer!
My thesis is about a phase noise measurement device I developed, which primary

use is to measure phase noise/jitter of audioband DACs. I probably won't be
focussing on jitter too much but would like to know if there even is one
accepted standard definition.

For example, in the different definitions I found so far, the seperation

between jitter and wander sometimes is given to be at 1Hz, 10Hz and sometimes
just mushy definitions like "very low frequencies"...

I doubt it is that important for my thesis anyway, but I'd really like to know

for myself, so if anyone has a pointer for me it would be greatly appreciated!

Datum: 17. April 2014 11:21:25 MESZ
An: "Discussion of precise time and frequency measurement"
Betreff: Re: [time-nuts] Jitter Definition
Antwort an: Discussion of precise time and frequency measurement
It depends on what your thesis is all about- you could try some of the ITU

documents for 'official' definitions but these may or may not be relevant to
your thesis.

DaveB, NZ
Sent: Thursday, April 17, 2014 2:54 PM
Subject: [time-nuts] Jitter Definition

Hello there,
I tried searching the archives (and google, IEEE, NIST, ITU), but didn't

really find a satisfying answer, so I thought I'd ask directly.

Is there any kind of standard definition for Jitter which is commonly

accepted?

I (think I) understood Jitter and phase noise by now, yet I need to give

some references in my bachelor's thesis, so I'm looking for a definition. So far
I haven't found a real definition of the different "types" (RMS,p2p,c2c,...) and
components(RJ,DJ) of Jitter, but I guess there must be some kind of accepted
standard!?

If anyone could point me to some "official sources" which are "accepted in

the industry", I'd be very grateful.

Thanks in advance and best regards
Hag
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Message: 5
Date: Fri, 18 Apr 2014 08:43:53 -0700
From: Chris Albertson <albertson.chris-***@public.gmane.org>
To: Discussion of precise time and frequency measurement
<time-nuts-***@public.gmane.org>
Subject: Re: [time-nuts] Measuring the accurcy of a wrist watch
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Steel makes very good springs. Are there any non-magnetic materials that
are
close?

I think they can use some kind of non-magnetic stainless steel

Also this might be a moot point because I got a good strong signal by
placing the watch on top of the guitar strings. I did not have to restring
the guitar. The wall clock works even some inches away. You don't have
to get really close to the magnets. If you were building a sensor, just
use a plain iron core and 1/4 pound of #40 wire
--
Chris Albertson
Redondo Beach, California


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