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 <[email protected]> To: time-nuts <[email protected]> Sent: Fri, Apr 18, 2014 10:00 am Subject: time-nuts Digest, Vol 117, Issue 66 Send time-nuts mailing list submissions to [email protected] To subscribe or unsubscribe via the World Wide Web, visit https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts or, via email, send a message with subject or body 'help' to [email protected] You can reach the person managing the list at [email protected] When replying, please edit your Subject line so it is more specific than "Re: Contents of time-nuts digest..." 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 <[email protected]> To: [email protected] Subject: Re: [time-nuts] time-nuts Digest, Vol 117, Issue 61 Message-ID: <[email protected]> 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! > > > > Von: "Dave Brown" <[email protected]> > Datum: 17. April 2014 11:21:25 MESZ > An: "Discussion of precise time and frequency measurement" <[email protected]> > Betreff: Re: [time-nuts] Jitter Definition > Antwort an: Discussion of precise time and frequency measurement <[email protected]> > > > 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 > > ----- Original Message ----- From: "HagaaarTheHorrible" > <[email protected]> > To: <[email protected]> > 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. >> >> In short: >> 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 >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > > > ------------------------------ Message: 2 Date: Fri, 18 Apr 2014 06:09:14 -0700 From: Jim Lux <[email protected]> To: [email protected] Subject: Re: [time-nuts] GPS antenna in silicon/RTV encapsulation Message-ID: <[email protected]> Content-Type: text/plain; charset=windows-1252; format=flowed On 4/17/14, 11:09 AM, Lester Veenstra wrote: > 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 <[email protected]> To: timenuts <[email protected]> Subject: [time-nuts] quartz clock/watch question Message-ID: <[email protected]> Content-Type: text/plain; charset=us-ascii When a quartz watch or clock is assembled, what method is used to get it as accurate as possible? ------------------------------ Message: 4 Date: Fri, 18 Apr 2014 10:12:46 -0400 From: Bob Camp <[email protected]> To: Discussion of precise time and frequency measurement <[email protected]> Subject: Re: [time-nuts] time-nuts Digest, Vol 117, Issue 61 Message-ID: <[email protected]> Content-Type: text/plain; charset=windows-1252 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 On Apr 18, 2014, at 9:17 AM, HagaaarTheHorrible <[email protected]> wrote: > 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! > > > > > > >> >> >> >> Von: "Dave Brown" <[email protected]> >> Datum: 17. April 2014 11:21:25 MESZ >> An: "Discussion of precise time and frequency measurement" <[email protected]> >> Betreff: Re: [time-nuts] Jitter Definition >> Antwort an: Discussion of precise time and frequency measurement <[email protected]> >> >> >> 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 >> >> ----- Original Message ----- From: "HagaaarTheHorrible" >> <[email protected]> >> To: <[email protected]> >> 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. >>> >>> In short: >>> 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 >>> _______________________________________________ >>> time-nuts mailing list -- [email protected] >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >> >> >> > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ------------------------------ Message: 5 Date: Fri, 18 Apr 2014 08:43:53 -0700 From: Chris Albertson <[email protected]> To: Discussion of precise time and frequency measurement <[email protected]> Subject: Re: [time-nuts] Measuring the accurcy of a wrist watch Message-ID: <CABbxVHuGHW=goo5rxbjhosjlspyfrxpt+shpc2azrwwfx_0...@mail.gmail.com> Content-Type: text/plain; charset=UTF-8 On Thu, Apr 17, 2014 at 11:12 PM, Hal Murray <[email protected]>wrote: > > > 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 ------------------------------ _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts End of time-nuts Digest, Vol 117, Issue 66 ****************************************** _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
