[time-nuts] low-g OCXO GPSDO
Hi guys, my apologies for the commercial part in the email. Does anyone have information on the typical g-sensitivity of crystals/oscillators? We see about 1 to 2E-09 frequency change when turning typical OCXO's around on their back (a 2g turn-over). We introduced a low-g GPSDO that is especially useful in mobile applications, for example inside a vehicle, or carried around by a user in a backpack etc. A normal OCXO would drift significantly when being turned around in any direction. That's one of the big advantages of Rb's, they compensate for the crystal error after a short drift... For that kind of use, we are putting a special very low-g OCXO on our board to reduce the frequency drift as much as possible (10x improvement desired over a standard crystal). You can see a picture in our press release at: _http://www.marketwire.com/mw/release.do?id=865007sourceType=3_ (http://www.marketwire.com/mw/release.do?id=865007sourceType=3) I am very interested to see what experience folks have with low-g crystals and OCXO's. Does anyone have experience with using active Crystal compensation for varying g-vectors? How about special crystals, or three-axis-crystal compensated systems etc? thanks, bye, Said **Get trade secrets for amazing burgers. Watch Cooking with Tyler Florence on AOL Food. (http://food.aol.com/tyler-florence?video=4?NCID=aolfod000302) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] HP 5334B rackmount ears
My HP5334B tabs look like this with a 1 3/4 inch seperation for the case holes and the same for the rack mount. http://i307.photobucket.com/albums/nn306/stanleyreynolds/hp1.jpg http://i307.photobucket.com/albums/nn306/stanleyreynolds/hp2.jpg a href=http://s307.photobucket.com/albums/nn306/stanleyreynolds/?action=viewcurrent=hp1.jpg; target=_blankimg src=http://i307.photobucket.com/albums/nn306/stanleyreynolds/hp1.jpg; border=0 alt=Photobucket/a a href=http://s307.photobucket.com/albums/nn306/stanleyreynolds/?action=viewcurrent=hp2.jpg; target=_blankimg src=http://i307.photobucket.com/albums/nn306/stanleyreynolds/hp2.jpg; border=0 alt=Photobucket/a - Original Message From: [EMAIL PROTECTED] [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Thursday, June 5, 2008 12:48:21 AM Subject: Re: [time-nuts] HP 5334B rackmount ears Hi Scott- I do have two that should work. One is marked HP 3490, so if that one uses the same you should be fine. The mounting holes (ear to counter) are 1 apart and are set back .5 from the front of the flange. I'd send you a pix, but my camera is hiding somewhere. -Dave -- Original message -- From: Scott Mace [EMAIL PROTECTED] Yes, it's a 2U. I think it's option 908, option 909 or something. Scott [EMAIL PROTECTED] wrote: I think I have some; what is the height? 2RU? -Dave -- Original message -- From: Scott Mace [EMAIL PROTECTED] Does anyone know where I can get a set of rackmount ears for the 5334B? I need to rack this unit and take off the feet. Scott ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] low-g OCXO GPSDO
A normal OCXO would drift significantly when being turned around in any direction. I've actually been wondering about what physical mechanism that causes this. I could understand how it could cause a phase shift, but I can't envision the cause of frequency shift. Does anyone know? Matt ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Fw: HP 5334B rackmount ears
My HP5334B tabs look like this with a 1 3/4 inch seperation for the case holes and the same for the rack mount. http://i307.photobucket.com/albums/nn306/stanleyreynolds/hp1.jpg http://i307.photobucket.com/albums/nn306/stanleyreynolds/hp2.jpg ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] low-g OCXO GPSDO
On Thu, 2008-06-05 at 13:02 -0400, [EMAIL PROTECTED] wrote: ... I am very interested to see what experience folks have with low-g crystals and OCXO's. Does anyone have experience with using active Crystal compensation for varying g-vectors? How about special crystals, or three-axis-crystal compensated systems etc? No personal experience, but this has been referenced here before: http://www.zyfer.com/documents/whitepapers/qz_low-g_4-04.pdf thanks, bye, Said -- Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Fw: HP 5334B rackmount ears
Correction my counter is a HP5334A not B sorry don't know if they are different. - Original Message From: Stanley Reynolds [EMAIL PROTECTED] To: time-nuts@febo.com Sent: Thursday, June 5, 2008 12:27:15 PM Subject: [time-nuts] Fw: HP 5334B rackmount ears My HP5334B tabs look like this with a 1 3/4 inch seperation for the case holes and the same for the rack mount. http://i307.photobucket.com/albums/nn306/stanleyreynolds/hp1.jpg http://i307.photobucket.com/albums/nn306/stanleyreynolds/hp2.jpg ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] low-g OCXO GPSDO
I've got some presentations on low-g OCXOs technology - I'll dig them out and send you a copy. Gives quite a bit of theory and also techniques for correcting g effects. Rob Kimberley -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Matt Ettus Sent: 05 June 2008 18:26 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] low-g OCXO GPSDO A normal OCXO would drift significantly when being turned around in any direction. I've actually been wondering about what physical mechanism that causes this. I could understand how it could cause a phase shift, but I can't envision the cause of frequency shift. Does anyone know? Matt ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] low-g OCXO GPSDO
Said, See my post to Matt. I have some useful info on g correction techniques. Rob Kimberley -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: 05 June 2008 18:02 To: time-nuts@febo.com Subject: [time-nuts] low-g OCXO GPSDO Hi guys, my apologies for the commercial part in the email. Does anyone have information on the typical g-sensitivity of crystals/oscillators? We see about 1 to 2E-09 frequency change when turning typical OCXO's around on their back (a 2g turn-over). We introduced a low-g GPSDO that is especially useful in mobile applications, for example inside a vehicle, or carried around by a user in a backpack etc. A normal OCXO would drift significantly when being turned around in any direction. That's one of the big advantages of Rb's, they compensate for the crystal error after a short drift... For that kind of use, we are putting a special very low-g OCXO on our board to reduce the frequency drift as much as possible (10x improvement desired over a standard crystal). You can see a picture in our press release at: _http://www.marketwire.com/mw/release.do?id=865007sourceType=3_ (http://www.marketwire.com/mw/release.do?id=865007sourceType=3) I am very interested to see what experience folks have with low-g crystals and OCXO's. Does anyone have experience with using active Crystal compensation for varying g-vectors? How about special crystals, or three-axis-crystal compensated systems etc? thanks, bye, Said **Get trade secrets for amazing burgers. Watch Cooking with Tyler Florence on AOL Food. (http://food.aol.com/tyler-florence?video=4?NCID=aolfod000302) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Fw: HP 5334B rackmount ears
The ears I have should be the same as the one on the right side in the hp2.jpg, except for the 1 spacing. -Dave -- Original message -- From: Stanley Reynolds [EMAIL PROTECTED] Correction my counter is a HP5334A not B sorry don't know if they are different. - Original Message From: Stanley Reynolds To: time-nuts@febo.com Sent: Thursday, June 5, 2008 12:27:15 PM Subject: [time-nuts] Fw: HP 5334B rackmount ears My HP5334B tabs look like this with a 1 3/4 inch seperation for the case holes and the same for the rack mount. http://i307.photobucket.com/albums/nn306/stanleyreynolds/hp1.jpg http://i307.photobucket.com/albums/nn306/stanleyreynolds/hp2.jpg ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] low-g OCXO GPSDO
Hi Bjoern, thanks for the pointer. Unfortunately they only say FEI propriatary compensation techniques without going into details. I am interested in the details :) I am wondering if we can get down to 1 to 5E-012/g in an inexpensive way without using accelerometers etc. thanks, bye, Said In a message dated 6/5/2008 10:39:02 Pacific Daylight Time, [EMAIL PROTECTED] writes: No personal experience, but this has been referenced here before: http://www.zyfer.com/documents/whitepapers/qz_low-g_4-04.pdf **Get trade secrets for amazing burgers. Watch Cooking with Tyler Florence on AOL Food. (http://food.aol.com/tyler-florence?video=4?NCID=aolfod000302) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] An interesting behavior with my Sulzer 2.5A...
Hi Gang! Being the season of thunderstorms and protracted power outages; As my UPS quit before the power restored, I am reminded of a behavior that I have always found curious: When the power fails on my Sulzer 2.5A, for more than a few minutes, the frequency takes a quick hop lower a few parts in E9. I then get to spend a couple of days bringing it back on frequency, and find that for the next several month it begins a very slow climb up in frequency back to where it was after the short interruption in power. Any ideas on what is happening? -Chuck Harris ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] low-g OCXO GPSDO
Cool! Thanks everyone for your feedback, bye, Said In a message dated 6/5/2008 11:08:07 Pacific Daylight Time, [EMAIL PROTECTED] writes: I've got some presentations on low-g OCXOs technology - I'll dig them out and send you a copy. Gives quite a bit of theory and also techniques for correcting g effects. Rob Kimberley **Get trade secrets for amazing burgers. Watch Cooking with Tyler Florence on AOL Food. (http://food.aol.com/tyler-florence?video=4?NCID=aolfod000302) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] low-g OCXO GPSDO
The PDF link listed by Björn below actually supersedes the ones I have on file, so please ignore my previous posts. Rob Kimberley -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Björn Gabrielsson Sent: 05 June 2008 18:38 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] low-g OCXO GPSDO On Thu, 2008-06-05 at 13:02 -0400, [EMAIL PROTECTED] wrote: ... I am very interested to see what experience folks have with low-g crystals and OCXO's. Does anyone have experience with using active Crystal compensation for varying g-vectors? How about special crystals, or three-axis-crystal compensated systems etc? No personal experience, but this has been referenced here before: http://www.zyfer.com/documents/whitepapers/qz_low-g_4-04.pdf thanks, bye, Said -- Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] low-g OCXO GPSDO
They use accelerometers and were getting better than 2E-12/g in 2004 but I've been a bit out of touch since then Rob K -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: 05 June 2008 19:20 To: time-nuts@febo.com Subject: Re: [time-nuts] low-g OCXO GPSDO Hi Bjoern, thanks for the pointer. Unfortunately they only say FEI propriatary compensation techniques without going into details. I am interested in the details :) I am wondering if we can get down to 1 to 5E-012/g in an inexpensive way without using accelerometers etc. thanks, bye, Said In a message dated 6/5/2008 10:39:02 Pacific Daylight Time, [EMAIL PROTECTED] writes: No personal experience, but this has been referenced here before: http://www.zyfer.com/documents/whitepapers/qz_low-g_4-04.pdf **Get trade secrets for amazing burgers. Watch Cooking with Tyler Florence on AOL Food. (http://food.aol.com/tyler-florence?video=4?NCID=aolfod000302) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] low-g OCXO GPSDO
From: Matt Ettus [EMAIL PROTECTED] Subject: Re: [time-nuts] low-g OCXO GPSDO Date: Thu, 5 Jun 2008 10:25:43 -0700 Message-ID: [EMAIL PROTECTED] A normal OCXO would drift significantly when being turned around in any direction. I've actually been wondering about what physical mechanism that causes this. I could understand how it could cause a phase shift, but I can't envision the cause of frequency shift. Does anyone know? Anything that deforms the actual crystal will slightly change the acoustical waveequation and thus the frequency. Crystals also deforms due to electrostatics, which have been used by NIST for finegrained phase modulation. The interested can make the exercise to model the crystal in detail by solving the Schröder equations and the various stress mechanism and then how that changes the acoustical waveequations. It's that simple. :) Actually, today I have been looking for articles relating to Kalman filter estimation of exponential frequency drift. The traditional phase, frequency and frequency drift does not match data very well. Curve-matching shows much better aggrement with exponential frequency. However, normal curve-matching does not match well with real time estimation. Most articles seems to use the linear drift. Ah well. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] low-g OCXO GPSDO
Hi Rob, there are unit out there that are not accelerometer compensated, and do extremely well too. But I think these are selected quartz crystals, with quite low yield and thus quite high cost.. We are looking for the holy grail: low cost and complexity, and very high performance. Maybe accelerometers are a must. bye, Said In a message dated 6/5/2008 11:38:24 Pacific Daylight Time, [EMAIL PROTECTED] writes: They use accelerometers and were getting better than 2E-12/g in 2004 but I've been a bit out of touch since then Rob K **Get trade secrets for amazing burgers. Watch Cooking with Tyler Florence on AOL Food. (http://food.aol.com/tyler-florence?video=4?NCID=aolfod000302) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] low-g OCXO GPSDO
On Thu, 2008-06-05 at 14:58 -0400, [EMAIL PROTECTED] wrote: We are looking for the holy grail: low cost and complexity, and very high performance. Maybe accelerometers are a must. They are not that expensive anymore. ADXL330 (3 axis +-3g analog) seems to be below $6. bye, Said -- Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] low-g OCXO GPSDO
From: Matt Ettus [EMAIL PROTECTED] Subject: Re: [time-nuts] low-g OCXO GPSDO Date: Thu, 5 Jun 2008 10:25:43 -0700 Message-ID: [EMAIL PROTECTED] A normal OCXO would drift significantly when being turned around in any direction. I've actually been wondering about what physical mechanism that causes this. I could understand how it could cause a phase shift, but I can't envision the cause of frequency shift. Does anyone know? Anything that deforms the actual crystal will slightly change the acoustical waveequation and thus the frequency. Crystals also deforms due to electrostatics, which have been used by NIST for finegrained phase modulation. I wonder what would happen to g-sensitivity if you ran the crystal with a DC bias across it. If you could pre-compress the crystal electrostatically, maybe it would become less sensitive to orientation. -- john, KE5FX ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] low-g OCXO GPSDO
In message [EMAIL PROTECTED], John Miles writes: Anything that deforms the actual crystal will slightly change the acoustical waveequation and thus the frequency. Crystals also deforms due to electrostatics, which have been used by NIST for finegrained phase modulation. I wonder what would happen to g-sensitivity if you ran the crystal with a DC bias across it. If you could pre-compress the crystal electrostatically, maybe it would become less sensitive to orientation. You might help the 2g test case (180° rotation), but you would still have the trouble with the 1g test case (90° rotation). -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 [EMAIL PROTECTED] | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] low-g OCXO GPSDO
Hmm, that's not a bad price at all. bye, Said In a message dated 6/5/2008 12:19:00 Pacific Daylight Time, [EMAIL PROTECTED] writes: Maybe accelerometers are a must. They are not that expensive anymore. ADXL330 (3 axis +-3g analog) seems to be below $6. **Get trade secrets for amazing burgers. Watch Cooking with Tyler Florence on AOL Food. (http://food.aol.com/tyler-florence?video=4?NCID=aolfod000302) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] HP 5334B rackmount ears
I have a pair which came from a 5334B and which I would gladly trade for the feet :-) Didier KO4BB -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Scott Mace Sent: Wednesday, June 04, 2008 5:48 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] HP 5334B rackmount ears Does anyone know where I can get a set of rackmount ears for the 5334B? I need to rack this unit and take off the feet. Scott ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] HP 5334B rackmount ears
This is what they look like: http://tonga.globat.com/~ko4bb.com//Test_Equipment/HP_5334B_Rack_Flanges/ The right one has some scuff marks in the paint, but the metal is fine. Didier KO4BB -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Scott Mace Sent: Wednesday, June 04, 2008 5:48 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] HP 5334B rackmount ears Does anyone know where I can get a set of rackmount ears for the 5334B? I need to rack this unit and take off the feet. Scott ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. No virus found in this incoming message. Checked by AVG. Version: 8.0.100 / Virus Database: 269.24.6/1481 - Release Date: 6/3/2008 7:31 PM ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] HP 5334B rackmount ears
There are two styles of rack ears for the 5334B. One is shown in Didier's picture. The other adds ears to the front panel 'handles' and the two are not interchangeable. Handles are useful for holding probes, etc., but you could take them off and add the ears shown in Didier's pictures. Joe -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Didier Juges Sent: Thursday, June 05, 2008 5:47 PM To: 'Discussion of precise time and frequency measurement' Subject: Re: [time-nuts] HP 5334B rackmount ears This is what they look like: http://tonga.globat.com/~ko4bb.com//Test_Equipment/HP_5334B_Rack_Flanges/ The right one has some scuff marks in the paint, but the metal is fine. Didier KO4BB -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Scott Mace Sent: Wednesday, June 04, 2008 5:48 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] HP 5334B rackmount ears Does anyone know where I can get a set of rackmount ears for the 5334B? I need to rack this unit and take off the feet. Scott ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. No virus found in this incoming message. Checked by AVG. Version: 8.0.100 / Virus Database: 269.24.6/1481 - Release Date: 6/3/2008 7:31 PM ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] USB to Serial Connectors for GPS Modules
Quoth Ulrich Bangert at 2008-06-05 13:58... consider the latency times of ANYTHING on a USB provided virtual serial connection to be in the order of 1 ms. If no serial data is send but only status signals change their state the latency can even be higher. Thanks (and to the others who responded to this). Just wanted to know where I was. I will make sure that I've got real serial ports with real kernel drivers for timing applications and use USB only for non time-critical stuff, like control messages, etc. (given a module with with 2 serial ports and only 1 port available on the house computer, for instance.) Cheers M -- Matthew Smith Smiffytech - Technology Consulting Web Application Development Business: http://www.smiffytech.com/ Personal: http://www.smiffysplace.com/ LinkedIn: http://www.linkedin.com/in/smiffy ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] HP 5334B rackmount ears
Didier, this is exactly what I need. I'll contact you off-list. Scott Didier Juges wrote: I have a pair which came from a 5334B and which I would gladly trade for the feet :-) Didier KO4BB -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Scott Mace Sent: Wednesday, June 04, 2008 5:48 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] HP 5334B rackmount ears Does anyone know where I can get a set of rackmount ears for the 5334B? I need to rack this unit and take off the feet. Scott ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] USB to Serial Connectors for GPS Modules
At 04:10 PM 6/5/2008, Matthew Smith wrote: Quoth Ulrich Bangert at 2008-06-05 13:58... consider the latency times of ANYTHING on a USB provided virtual serial connection to be in the order of 1 ms. If no serial data is send but only status signals change their state the latency can even be higher. Thanks (and to the others who responded to this). Just wanted to know where I was. I will make sure that I've got real serial ports with real kernel drivers for timing applications and use USB only for non time-critical stuff, like control messages, etc. (given a module with with 2 serial ports and only 1 port available on the house computer, for instance.) Cheers M I wouldn't assume that the latency on a hardware serial port, depending on the OS, is any better than 1 ms, either. Particularly if you are expecting the process to be something like: value change on serial port line (Carrier Det) interrupt from hardware fielded by serial port ISR blocked process waiting on CD interrupt marked as ready to run indeterminate time waiting for next scheduler pass process starts running. While it might only take microseconds to fire up the ISR, it could be milliseconds before your process starts to run (unless you're using something at the device driver level?) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PCB design questions
On Monday 02 June 2008 02:19:52 pm David C. Partridge wrote: I'm now thinking ahead to the PCB requirement... http://focus.ti.com/lit/an/scaa082/scaa082.pdf http://www.ti.com/litv/pdf/scaa082 Application Notes Abstract High Speed Layout Guidelines This application report addresses high-speed signals such as clock signals and their routing and gives designers a review of the important coherences. With some simple rules, electromagnetic interference problems can be minimized without using complicated forumulas and expensive simulation tools. Section 1 gives a short introduction to theory, section 2 focuses on practical PCB design rules. Either section can be read independently. -- http://www.wearablesmartsensors.com/ http://www.softwaresafety.net/ http://www.designer-iii.com/ http://www.unusualresearch.com/ ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
