Re: [time-nuts] Fury - Rubidium
Hi Scott, a cool thing to try is to put the unit into manual holdover by issuing the command sync:holdover:init The unit will act as if the GPS antenna has been removed, but GPSCon will continue to show the 1PPS phase drift against GPS. Thus you can see how stable your LPRO is over time when the unit is in holdover. You can restart normal locking with the command sync:holdover:rec:init On a good DOCXO, we would see less than 2000ns drift over a day when the unit has been stable for a week or so. I believe the limits of the time interval display are about +/- 2000ns. bye, Said In a message dated 7/27/2010 08:42:01 Pacific Daylight Time, sm...@intt.net writes: I test it by changing the antenna delay. It should recover within a reasonable time. Bumping the coarsedac is typically too much change and takes longer to recover. I run it with a 20ns offset to my z3801a, and they always stay within 20ns of other. I've had the Fury running for about 5400 hours since the last reboot, running v1.21 firmware. It stays within +-10ns, usually it's between +-5ns. Over 24hrs, gpscon reports TI average 0.15 or so and stddev around 2.5ns. ___ 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] Fury - Rubidium - PIS
Hi Pretty much all Rb's tune by changing the magnetic field. Bob On Jul 28, 2010, at 12:52 AM, saidj...@aol.com wrote: Hi Scott, yes, Rb's tend to have many orders of magnitude smaller control ranges than OCXO's, so it takes longer to phase lock. What's even worse is hysterisis, eg. we have seen units that jump back and forth between two control voltage values. This tends to happen in TCXO's and Rbs from what I can tell, not so much in good OCXO's. It seems that these units do not change their output frequency until the EFC voltage change reaches some threshold, then the frequency jumps in a large value. OCXO's seem to react instantly to even the slightest LSB changes on our 24 bit DAC. Many Rb's and TCXO's seem to have this spring-like effect, and that causes some chasing of the phase as the oscillators ignores the EFC voltage changes until they reach a certain level, at which time they over-compensate and the effect reverses. I am wondering if adding some dithering noise would help prevent this effect, where the noise bandwidt is below the Rb's control bandwidth so as not to add ADEV instability... Does anyone know how popular Rb's adjust their frequency? Is it through linear methods such as Varactor diodes? Or do they use an ADC to sample the EFC voltage, thus creating quantization errors that could be the cause of the hysterisis we sometimes see? Brian, on a locked DOCXO unit (after a day or so typically) we would like to see below 5ns SD on the GPS TI. Good DOCXO units regularly achieve 2.5ns. No reason a good Rb should not be able to achieve that as well. The DOCXO unit running at the University of Colima for example regularly achieves ~1.8ns SD. For some reason the TI indicator has not been visible for some months now though, but the plot still speaks for itself. Notice also the small control voltage range of less than 50 microvolts typically: _http://resco.ucol.mx/Fury/gpsstat.htm_ (http://resco.ucol.mx/Fury/gpsstat.htm) bye, Said In a message dated 7/27/2010 20:11:00 Pacific Daylight Time, sm...@intt.net writes: After _MANY_ hours of watching and playing with different settings, I came to the conclusion that you just need to be patient when using Fury+Rb, don't expect it to converge like an OCXO, but it will over a few hours and give you a good result as long as you have stable power and shield it from air streams. ___ 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] Fury - Rubidium
Said, I would like to take advantage of the Fury TempCo capabilities when using an Rb. I have been looking for the thru-hole pad which you say is next to C67 but I can't find a C67. Consider that I am over 60 and eyesight is challenged but I have found C68 with nearby pads. Can you give us some additional components nearby to zero in on this allusive component. Thanks! Regards... Don - Original Message - From: saidj...@aol.com To: time-nuts@febo.com Sent: Tuesday, July 27, 2010 9:07 PM Subject: Re: [time-nuts] Fury - Rubidium Hi Scott, yes the pads are there, you can use the through-hole pad right next to C67 and a standard ground pad for the Thermistor. There will be 10.5V across the thermistor. Connect the thermistor to your Rb case. You should be able to connect two 10K Thermistors in parallel to get a good reading without excessive self-heating of the thermistors, while generating enough current through them that can be measured by the ADC. You can check the thermistor current using the meas? command. If the thermistor is not drawing enough current for the ADC, then simply place a 2.2K resistor in parallel to it. The software needs to be enabled to support measuring and applying a tempco correction, by default I think the boards were shipped with only aging compensation enabled. Us the following command to enable tempco correction: serv:tas 2,288,600,50,0.05 Check the settings with: serv:tas? The first number is the mode (0 is all off, 1 is aging only, 2 is aging and tempco correction). The second number is the memory usage, 288 points in this case. The third number is the sensing frequency in seconds, so 10 minute intervals in this example. 288 points * 10 minutes is 48 hours of memory. The fourth number is the maximum phase offset allowed for a sense point, in this case +/-50ns. The last item is the required frequency error estimate for a sense point, in this case +/-0.05ppb. bye, Said In a message dated 7/27/2010 17:07:31 Pacific Daylight Time, sm...@intt.net writes: Said, Did the OEM units (from way back) ship with an open pad for the thermistor? I thought that wouldn't work unless it was drawing oven current from the Fury. It would be neat to add some tempco into the mix instead of just trying to shield it from HVAC cycling. The particular LPRO-101 that I'm using now, doesn't seem to be as sensitive as others to temp. I was using a different LPRO originally and when I plotted the Fury board temp sensor with GPSCON you could see the impact of the cycling, now with this one you would be hard pressed to pick it out. The X72 was very sensitive to temp changes, EFC tracked the temp quite well. 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] Fury - Rubidium
Hi I know I am repeating my self but reading Brian's experience with a FRS and the Shera controller, here I go again. Not having any luck contacting Brooks Shera, I did fool the controller with hardware changes and have very good results controlling a FRK-H. Comparing it with a Cesium, it is right up there limited only by my present measuring capabilities. Rubidium's are today available for less than $ 100 so are Tbolt's. How ever a Tbolt is a timing device and most of us have no ability or info to change it to a frequency device. Again I ask is there any interest to revive the Brooks Shera design with a few updates? Total hardware cost would be less than $ 40 not counting the GPS receiver. The result would be a world class standard for less than $ 200 counting all of you that already have rubidium's or high performance OCXO's it would be less than $ 100. An other advantage if done right it could also be a programmable digital loop to discipline a high performance oscillator to for example a not so hot short term rubidium. My problem to complete the project is I am an admitted ZERO when it comes to code and software. Bert Kehren In a message dated 7/27/2010 8:46:37 P.M. Eastern Daylight Time, kilodelta4foxm...@gmail.com writes: I read the article on PID on Wikipedia last night. I do not fully understand it, but I see/learning some of the relationship. I did a test on the FRS-C rubidium. The average frequency was 10 000 000.0025 hertz at the rubidium 10 turn dial dial setting of 255, and the control voltage out of the pot was 1.7900 volts. I recorded the frequency for a while and then changed frequency to see how long it took to get there. I changed the dial setting to 516(3.5800V) and it took 8 seconds for the rubidium to change frequency and settle on a average frequency of 10, 000 000.0131 hertz. I did another test and the rubidium dial setting was 000 for a control voltage of 0.068V and the average frequency was 9 999 999.9933 hertz. The dial setting was changed to 721 for a control voltage of 4.V and the average frequency was 10 000 000.0216 hertz The measurements were taken with a HP5370B time interval counter referenced to a HP5065A rubidium oscillator. The data was recorded using a ProLogix GPIB adapter. The data was recorded in 10 minute intervals with the data coming in at one measurement a second. When the frequency was changed, I allowed 20 minutes between the recordings. Based on the above measurements, Said, can you recommend some starting point for the DAC Gain, EFC Scale, and the EFC Damping ? Also from previous measurements, I know this particular rubidium was at 9x10E-11 at 0.1 sec, 1.8x10E-11 at 1 second, 5x10E-12 at 10 seconds, 1.5x10E-12 at 100 seconds, 7x10E-13 for 1000 seconds, and 2.5x10E-13 for 1 seconds - running on a Shera GPS controller - which the PIC was modified for this rubidium (it was changed from a 30 second time interval measurement to 120 seconds, and Shera changed the sensitivity of the PIC to 1X10-9/volt). Thanks to Don and Scott for the ops info. Thanks Brian KD4FM On 7/27/2010 2:57 PM, saidj...@aol.com wrote: Hi guys, it may help to increase DAC gain to get faster recovery times from bumps etc. On an OCXO, the frequency recovery from an upset should happen within a couple of minutes, definitely less than 15 minutes to achieve frequency lock. The phase recovery (to 0ns offset) may take a couple of hours to do. If it takes a very long time to recover, then I think increasing the DAC gain, or alternatively the EFCS and PHASECO together may help. Wikipedia has some good instructions on how to optimize PID type controller gains to get the fastest response with minimal noise... Also, please make sure to disable temperature compensation when using the external source, unless a thermistor is connected to the board, sensing the Rb temperature. Otherwise the temperature compensation may add noise due to it scaling the gain to huge values due to the missing thermistor. bye, Said In a message dated 7/27/2010 09:58:41 Pacific Daylight Time, true-...@swbell.net writes: My experience is very similar to Scott's. I ran many hours with both an LPRO-101 and FE-5680A. The disciplining behavior and Fury settings were the same for either Rb. My biggest disappointment was the recovery time due to various common or intentional bumps or especially, after power loss. I also had to let the system settle in for a week before acceptable tracking smoothed out. Any long term slope to the EFC trace (gpscon) caused excessive hunting and this didn't settle down until the Rb was VERY stable. My gpscon TI and stddev was virtually the same as Scott's if I had EFCS set to 1.0 to 1.5 but recovery was unacceptable (maybe 24-hours) so I usually ran at 2.0 or 3.0 with slight degrading of stddev to
Re: [time-nuts] Fury - Rubidium
In a message dated 28/07/2010 18:10:18 GMT Daylight Time, ewkeh...@aol.com writes: How ever a Tbolt is a timing device and most of us have no ability or info to change it to a frequency device. Hi Bert Is it possible you're confusing the Thunderbolt with something else? Surely, being a 10MHz GPS disciplined oscillator, the Thunderbolt is very much a frequency device? regards Nigel GM8PZR ___ 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] Fury - Rubidium
Hi Don, sorry about the hassle, please see the attached image of a Fury GPSDO PCB. C67 is on the bottom side of the PCB. The hole is one of the five mounting holes of the OCXO, close to the edge of the PCB, next to one of the SMA connectors. I drew a white circle around it. You can solder the two thermistor wires simply across that capacitor (the other side of the cap is connected to ground), or you can connect one wire to the hole next to C67, and the other wire to a ground post on one of the connectors. Hope that helps, Said In a message dated 7/28/2010 09:19:58 Pacific Daylight Time, true-...@swbell.net writes: Said, I would like to take advantage of the Fury TempCo capabilities when using an Rb. I have been looking for the thru-hole pad which you say is next to C67 but I can't find a C67. Consider that I am over 60 and eyesight is challenged but I have found C68 with nearby pads. Can you give us some additional components nearby to zero in on this allusive component. Thanks! Regards... Don C67.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] Fury - Rubidium - PIS
Hi Bob, do we know the resolution of that change for different Rb units? Ergo, will a say 10 microvolt change in EFC voltage actually make a difference in the output frequency or be lost in hysterisis? Thanks, Said In a message dated 7/28/2010 04:23:34 Pacific Daylight Time, li...@rtty.us writes: Hi Pretty much all Rb's tune by changing the magnetic field. Bob ___ 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] Updated Shera controller
Bert, I for one, would be interested in that. ___ 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] Updated Shera controller
What could you help with? Bert In a message dated 7/28/2010 3:05:26 P.M. Eastern Daylight Time, wpxs...@gmail.com writes: Bert, I for one, would be interested in that. ___ 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] Updated Shera controller
Instead of copying the Shera controller albeit with higher resolution its probably more cost effective to choose a microprocessor with built in time stamping capability. The PIC24FJ128GA for example allows 30ns timestamping resolution via its external timer capture inputs. Other microprocessors (or DSPs) are available with even higher timestamping resolution. Since modern GPS timing receivers can have a timing noise of a few ns (after sawtooth correction) it may also be useful to use a simple time to digital converter (eg TAC + ADC) to achieve a resolution of 1ns or so. Several microprocessors have built in ADCs with sufficient resolution and low leakage to allow trimpots, external buffer opamps etc to be dispensed with. The trimpots being replaced by interleaved software calibration. The microprocessor initiates a TAC calibration cycle after each external PPS event is timestamped. The resultant sequence of calibration coefficients can then be filtered and used to correct the PPS fine time stamp sequence. If the microprocessor also has a couple of PWM outputs then these can be used to implement a high resolution synchronously filtered DAC The synchronously filtered DAC requires a stable reference, a couple of opamps, a few analog switches plus a few resistors and capacitors. Neither the resistors or capacitors need to be extremely close tolerance parts. Bruce ewkeh...@aol.com wrote: What could you help with? Bert In a message dated 7/28/2010 3:05:26 P.M. Eastern Daylight Time, wpxs...@gmail.com writes: Bert, I for one, would be interested in that. ___ 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] Updated Shera controller
In message 4c5092fa.2030...@xtra.co.nz, Bruce Griffiths writes: Instead of copying the Shera controller albeit with higher resolution its probably more cost effective to choose a microprocessor with built in time stamping capability. Uhm, isn't this exactly where you want to use the still-smelling-like-brand-new-car PICTIC II with a good DAC and a microcontroller ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@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. ___ 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] Updated Shera controller
Yes, you are absolutely right and I have tried to get Richard to do it. Bert In a message dated 7/28/2010 4:47:46 P.M. Eastern Daylight Time, p...@phk.freebsd.dk writes: In message 4c5092fa.2030...@xtra.co.nz, Bruce Griffiths writes: Instead of copying the Shera controller albeit with higher resolution its probably more cost effective to choose a microprocessor with built in time stamping capability. Uhm, isn't this exactly where you want to use the still-smelling-like-brand-new-car PICTIC II with a good DAC and a microcontroller ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@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. ___ 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] Updated Shera controller
One more comment $ 40 would cover every thing including PC board, May go up to 50 depending what D/A you use. Bert In a message dated 7/28/2010 4:47:46 P.M. Eastern Daylight Time, p...@phk.freebsd.dk writes: In message 4c5092fa.2030...@xtra.co.nz, Bruce Griffiths writes: Instead of copying the Shera controller albeit with higher resolution its probably more cost effective to choose a microprocessor with built in time stamping capability. Uhm, isn't this exactly where you want to use the still-smelling-like-brand-new-car PICTIC II with a good DAC and a microcontroller ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@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. ___ 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] Updated Shera controller
ewkeh...@aol.com wrote: One more comment $ 40 would cover every thing including PC board, May go up to 50 depending what D/A you use. Bert In a message dated 7/28/2010 4:47:46 P.M. Eastern Daylight Time, p...@phk.freebsd.dk writes: In message4c5092fa.2030...@xtra.co.nz, Bruce Griffiths writes: Instead of copying the Shera controller albeit with higher resolution its probably more cost effective to choose a microprocessor with built in time stamping capability. Uhm, isn't this exactly where you want to use the still-smelling-like-brand-new-car PICTIC II with a good DAC and a microcontroller ? Not really its both overkill as it doesnt timestamp, it only measures a time interval and underkill in that theres no DAC. There are also some concerns about the settling time of the TAC buffer opamp which isnt strictly necessary for the lower resolution required in this application. PPS timestamping only needs a single TAC. Bruce ___ 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] Fury - Rubidium
Nigel I do not think so. Early on I did try a Tbolt and did run a comparison with my Cesium, maybe I did something wrong, but to me it looked like they where changing the OCXO frequency to correct timing. I got rid of it and instead modified my Shera for Rubidium. Any comments out there from people controlling their rubidium with a Tbolt replacing the OCXO? Bert In a message dated 7/28/2010 2:45:53 P.M. Eastern Daylight Time, gandal...@aol.com writes: In a message dated 28/07/2010 18:10:18 GMT Daylight Time, ewkeh...@aol.com writes: How ever a Tbolt is a timing device and most of us have no ability or info to change it to a frequency device. Hi Bert Is it possible you're confusing the Thunderbolt with something else? Surely, being a 10MHz GPS disciplined oscillator, the Thunderbolt is very much a frequency device? regards Nigel GM8PZR ___ 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] Updated Shera controller
Full circle back to the software, the number of units sold, the cost per hour and time to complete project would determine the software cost. Would not surprise me if the software would be the biggest expense till you break the 1000 unit mark unless the cost per hour was very low. As a hardware guy at heart it is hard for me to assign a cost/value to software ;-) Stanley - Original Message From: ewkeh...@aol.com ewkeh...@aol.com To: time-nuts@febo.com Sent: Wed, July 28, 2010 4:08:25 PM Subject: Re: [time-nuts] Updated Shera controller One more comment $ 40 would cover every thing including PC board, May go up to 50 depending what D/A you use. Bert In a message dated 7/28/2010 4:47:46 P.M. Eastern Daylight Time, p...@phk.freebsd.dk writes: In message 4c5092fa.2030...@xtra.co.nz, Bruce Griffiths writes: Instead of copying the Shera controller albeit with higher resolution its probably more cost effective to choose a microprocessor with built in time stamping capability. Uhm, isn't this exactly where you want to use the still-smelling-like-brand-new-car PICTIC II with a good DAC and a microcontroller ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@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. ___ 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] Updated Shera controller
I assume that some one will donate their time end effort like I am presently doing on the Dual Mixer I have spend in excess of $1000 on the project and untold hours and do not expect any payback. I thought that is what time-nuts is all about. Bert Kehren In a message dated 7/28/2010 6:06:39 P.M. Eastern Daylight Time, stanley_reyno...@yahoo.com writes: Full circle back to the software, the number of units sold, the cost per hour and time to complete project would determine the software cost. Would not surprise me if the software would be the biggest expense till you break the 1000 unit mark unless the cost per hour was very low. As a hardware guy at heart it is hard for me to assign a cost/value to software ;-) Stanley - Original Message From: ewkeh...@aol.com ewkeh...@aol.com To: time-nuts@febo.com Sent: Wed, July 28, 2010 4:08:25 PM Subject: Re: [time-nuts] Updated Shera controller One more comment $ 40 would cover every thing including PC board, May go up to 50 depending what D/A you use. Bert In a message dated 7/28/2010 4:47:46 P.M. Eastern Daylight Time, p...@phk.freebsd.dk writes: In message 4c5092fa.2030...@xtra.co.nz, Bruce Griffiths writes: Instead of copying the Shera controller albeit with higher resolution its probably more cost effective to choose a microprocessor with built in time stamping capability. Uhm, isn't this exactly where you want to use the still-smelling-like-brand-new-car PICTIC II with a good DAC and a microcontroller ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@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. ___ 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] Updated Shera controller
Paul, Interesting you should point this out as the PICTIC was a spin-off of a 5-year effort to modernize the Shera controller for my own use. The 42ns TIC in the Shera was a weak point and a different TIC with higher resolution was needed if sawtooth correction was desired. My GPSMAX controller uses a smart divider to supply a synchronized 1PPS to the panel and a delayed 500K to the PICTIC front end allowing the 1PPS timing to be varied by adjusting the controller setpoint. Just the TS274 portion of the PICTIC II interpolator is used for a gain of 400 with the gain reduced to 100 to give 1ns resolution. Over 100 serial commands allow remote operation and monitoring over a serial link, and all process variables can be displayed or adjusted on command. Accumulation times of 30, 60, 120, and 240 seconds were added for higher stability sources. Accumulated sawtooth data from a Motorola GPS is used to correct the accumulated TIC value prior to subtracting the setpoint and sending the error to the Shera filter. The filter output passes thru a scaler and is added to a correction register, then the correction register value is sent to a 23-bit DAC similar to the 22-bit design used in the SRS PRS10 Rb. The correction register can be loaded directly by serial command to set the frequency offset, eliminating the offset trimmer and associated loss of sensitivity and noise pickup. The scaler allows loop gain adjustment for differing oscillators by software command without changing resistors and allows a direct to DAC connection for many oscillators. A temperature sensor and 1PPS fail detection were added along with age and temperature compensation in holdover. The direct to DAC connection and the higher resolution of the interpolating front end adds sufficient gain for use with most Rb sources. Richard In message 4c5092fa.2030...@xtra.co.nz, Bruce Griffiths writes: Instead of copying the Shera controller albeit with higher resolution its probably more cost effective to choose a microprocessor with built in time stamping capability. Uhm, isn't this exactly where you want to use the still-smelling-like-brand-new-car PICTIC II with a good DAC and a microcontroller ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@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. ___ 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] Updated Shera controller
FYI, The TS272/TS274 have a slew rate of 5.5v/us at unity gain, the max voltage on the cap is 2.7v in the new design, and the voltage is read 10us after sample complete, so the buffer should have time to stabilize after the sample before being read. Richard Bruce wrote: Not really its both overkill as it doesnt timestamp, it only measures a time interval and underkill in that theres no DAC. There are also some concerns about the settling time of the TAC buffer opamp which isnt strictly necessary for the lower resolution required in this application. PPS timestamping only needs a single TAC. Bruce ___ 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] Updated Shera controller
Bert, In discussions with Brooks Shera the approach we are contemplating is an interpolating TIC and 0-5v output add-on board for use with his controller board. Minor modifications to the AA engineering board will route the XO to an interpolating front end and route the outputs back to the controller board. The +/- 3v output will route to the new board, which will supply 0-5v for an Rb. A new controller PIC would be added, and the upgrade would be complete. So don't get rid of those old Shera controllers just yet, an upgrade is in the works. It won't have the features of the GPSMAX as Brooks thinks we need to KISS the design, but it will increase the resolution and gain so the original board can be used with Rubidium sources. Richard Yes, you are absolutely right and I have tried to get Richard to do it. Bert In a message dated 7/28/2010 4:47:46 P.M. Eastern Daylight Time, p...@phk.freebsd.dk writes: In message 4c5092fa.2030...@xtra.co.nz, Bruce Griffiths writes: Instead of copying the Shera controller albeit with higher resolution its probably more cost effective to choose a microprocessor with built in time stamping capability. Uhm, isn't this exactly where you want to use the still-smelling-like-brand-new-car PICTIC II with a good DAC and a microcontroller ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@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. ___ 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] TBolt - Rubidium
Hi, I am very slowly putting together a LPRO with a thermal bootstrap temperature control and clean power supplies (in a separate box). The LPRO is on a 1/4 inch aluminium plate with fins on the other side. The LPRO and plate are in a foam plastic insulation jacket. A small brushless DC fan on the back of the box will suck air over the fins and it is used to control the temperature of the plate mounting the LPRO. It seems to hold temperature to about 1/10 degree. The unit is going into a steel box to further reduce the ambient magnetic flux. The frequency trim of the LPRO is a pair of trim pots (coarse and fine) with a quality voltage reference. Initially a phase detector and chart recorder will be used with a TBolt to set the frequency of the LPRO. However what I would like to do is use a TBolt to discipline the LPRO so that short and long term accuracy was maximised. Has anyone set up an LPRO with a TBOLT? How was it done? Was it successful? cheers, Neville Michie ___ 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] Fury - Rubidium
After about 19hours of holdover, only ~45ns. Now let's see how well it recovers. Scott On 07/28/2010 01:02 AM, saidj...@aol.com wrote: Hi Scott, a cool thing to try is to put the unit into manual holdover by issuing the command sync:holdover:init The unit will act as if the GPS antenna has been removed, but GPSCon will continue to show the 1PPS phase drift against GPS. Thus you can see how stable your LPRO is over time when the unit is in holdover. You can restart normal locking with the command sync:holdover:rec:init On a good DOCXO, we would see less than 2000ns drift over a day when the unit has been stable for a week or so. I believe the limits of the time interval display are about +/- 2000ns. bye, Said In a message dated 7/27/2010 08:42:01 Pacific Daylight Time, sm...@intt.net writes: I test it by changing the antenna delay. It should recover within a reasonable time. Bumping the coarsedac is typically too much change and takes longer to recover. I run it with a 20ns offset to my z3801a, and they always stay within 20ns of other. I've had the Fury running for about 5400 hours since the last reboot, running v1.21 firmware. It stays within +-10ns, usually it's between +-5ns. Over 24hrs, gpscon reports TI average 0.15 or so and stddev around 2.5ns. ___ 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. attachment: export.png___ 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] Pictic II boards are here !
Please, for two pieces, how do I pay , for France ? Thanks Bernard. - Original Message - From: Stanley Reynolds stanley_reyno...@yahoo.com To: time-nuts@febo.com Sent: Wednesday, July 21, 2010 12:08 AM Subject: [time-nuts] Pictic II boards are here ! Paypal to stanley_reyno...@yahoo.com . Yes I still have extra boards. Stanley ___ 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. --- Orange vous informe que cet e-mail a ete controle par l'anti-virus mail. Aucun virus connu a ce jour par nos services n'a ete detecte. ___ 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] TBolt - Rubidium
Hi I think there are some significant hurdles to overcome with a TBolt directly driving a Rb. The TBolt assumes it can pull the oscillator pretty far in order to align the pps signals. It also looks like the internal math may not be very happy with Rb sensitivities. I think better results will be had with a loop between the TBolt OCXO and the Rb. Bob On Jul 28, 2010, at 8:11 PM, Neville Michie namic...@gmail.com wrote: Hi, I am very slowly putting together a LPRO with a thermal bootstrap temperature control and clean power supplies (in a separate box). The LPRO is on a 1/4 inch aluminium plate with fins on the other side. The LPRO and plate are in a foam plastic insulation jacket. A small brushless DC fan on the back of the box will suck air over the fins and it is used to control the temperature of the plate mounting the LPRO. It seems to hold temperature to about 1/10 degree. The unit is going into a steel box to further reduce the ambient magnetic flux. The frequency trim of the LPRO is a pair of trim pots (coarse and fine) with a quality voltage reference. Initially a phase detector and chart recorder will be used with a TBolt to set the frequency of the LPRO. However what I would like to do is use a TBolt to discipline the LPRO so that short and long term accuracy was maximised.t Has anyone set up an LPRO with a TBOLT? How was it done? Was it successful? cheers, Neville Michie ___ 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] HP 5335A Option 040
Greetings to the timekeepers. I have enjoyed many of the comments on this list over the past few years. I have a HP 5335A counter with Option 040. I have found info on options 10, 20 and 30. Can anyone on the list provide any info on option 040? Thanks in advance. Gordon gpba...@compuserve.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.
[time-nuts] (no subject)
Thankyou to all those who responded to my question...Don. ___ 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] Fury - Rubidium
That's an average accuracy of 6.6E-013 over 19 hours. Impressive. bye, Said In a message dated 7/28/2010 18:21:12 Pacific Daylight Time, sm...@intt.net writes: After about 19hours of holdover, only ~45ns. Now let's see how well it recovers. Scott On 07/28/2010 01:02 AM, saidj...@aol.com wrote: Hi Scott, a cool thing to try is to put the unit into manual holdover by issuing the command sync:holdover:init The unit will act as if the GPS antenna has been removed, but GPSCon will continue to show the 1PPS phase drift against GPS. Thus you can see how stable your LPRO is over time when the unit is in holdover. You can restart normal locking with the command sync:holdover:rec:init On a good DOCXO, we would see less than 2000ns drift over a day when the unit has been stable for a week or so. I believe the limits of the time interval display are about +/- 2000ns. bye, Said ___ 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] Fury - Rubidium
Recovery from holdover was fine as well. Scott On 07/28/2010 11:21 PM, saidj...@aol.com wrote: That's an average accuracy of 6.6E-013 over 19 hours. Impressive. bye, Said In a message dated 7/28/2010 18:21:12 Pacific Daylight Time, sm...@intt.net writes: After about 19hours of holdover, only ~45ns. Now let's see how well it recovers. Scott On 07/28/2010 01:02 AM, saidj...@aol.com wrote: Hi Scott, a cool thing to try is to put the unit into manual holdover by issuing the command sync:holdover:init The unit will act as if the GPS antenna has been removed, but GPSCon will continue to show the 1PPS phase drift against GPS. Thus you can see how stable your LPRO is over time when the unit is in holdover. You can restart normal locking with the command sync:holdover:rec:init On a good DOCXO, we would see less than 2000ns drift over a day when the unit has been stable for a week or so. I believe the limits of the time interval display are about +/- 2000ns. bye, Said ___ 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. attachment: export.png___ 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 5335A Option 040
From a 1993 HP Catalog: HP5335A Option 40 Expanded HP-IB Control Adds remote selection of low-pass filter, ac/dc coupling, attenuator, dc triggering level, and input impedance for Channels A and B. On 7/28/2010 7:24 PM, Gordon Batey wrote: Greetings to the timekeepers. I have enjoyed many of the comments on this list over the past few years. I have a HP 5335A counter with Option 040. I have found info on options 10, 20 and 30. Can anyone on the list provide any info on option 040? Thanks in advance. Gordon gpba...@compuserve.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. ___ 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 5335A Option 040
And two extra buttons in the group on the right (now 8 total there). John Allen -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Rex Sent: Thursday, July 29, 2010 1:06 AM To: gpba...@compuserve.com; Discussion of precise time and frequency measurement Subject: Re: [time-nuts] HP 5335A Option 040 From a 1993 HP Catalog: HP5335A Option 40 Expanded HP-IB Control Adds remote selection of low-pass filter, ac/dc coupling, attenuator, dc triggering level, and input impedance for Channels A and B. On 7/28/2010 7:24 PM, Gordon Batey wrote: Greetings to the timekeepers. I have enjoyed many of the comments on this list over the past few years. I have a HP 5335A counter with Option 040. I have found info on options 10, 20 and 30. Can anyone on the list provide any info on option 040? Thanks in advance. Gordon gpba...@compuserve.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. ___ 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] HP 5335A Option 040
The manual on the Agilent site (preliminary) doesn't mention 040, but the later manual (available from Artekmedia) does. John Allen -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Gordon Batey Sent: Wednesday, July 28, 2010 10:24 PM To: time-nuts@febo.com Subject: [time-nuts] HP 5335A Option 040 Greetings to the timekeepers. I have enjoyed many of the comments on this list over the past few years. I have a HP 5335A counter with Option 040. I have found info on options 10, 20 and 30. Can anyone on the list provide any info on option 040? Thanks in advance. Gordon gpba...@compuserve.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. ___ 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] Updated Shera controller
stanley_reyno...@yahoo.com said: Full circle back to the software, the number of units sold, the cost per hour and time to complete project would determine the software cost. Would not surprise me if the software would be the biggest expense till you break the 1000 unit mark unless the cost per hour was very low. As a hardware guy at heart it is hard for me to assign a cost/value to software ;-) That line of thinking is probably appropriate for a commercial project. For a hobby/volunteer project, software can be free. Consider Lady Heather as an example. In this context, there are two types of software. There is the software you run on the board you build. There is also the software you use to develop the software you run. I'm assuming a volunteer would write the software just like volunteers have designed boards. I'm not familiar with windows. I think PIC and AVR come with free software for windows which works well with their low cost development platforms. The compiler may be crippled to get you to buy the real version from somebody, but I'm pretty sure it's good enough to get well off the ground. I'm not familiar with what's available from the vendors for ARM. gcc has good support for PIC, AVR, and ARM. There may be better, but it's well past good enough. (It runs on windows if you use cygwin.) If you aren't using the vendor packages, you also need a utility to download the compiled bits. I'm pretty sure I could find one, and/or write one from scratch. There might be a third type of software, a library that you use in the software you write, say a FFT package that's optimized for the CPU you are using. In the context of low volume hobby projects, it's probably simpler/cheaper to use a bigger/faster CPU. Or perhaps you need an OS. If you depend on a commercial OS, somebody would have to buy a license. Linux is free and runs on ARM. NetBSD runs on ARM. I'm not sure about the other BSD variants. That's 1/2 :) I expect most of the code we would be interested in would be low level, just collect the data and pass it off to a PC to do the number crunching, display, and archiving. As such it doesn't need an OS. -- These are my opinions, not necessarily my employer's. I hate spam. ___ 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] FS: 5370A
Ok guys, it has been sitting on my floor far too long and I don't know when I'll get around to working on it. When I last messed with it, I went through quite a few of the performance tests and IIRC, most passed. It measures frequency ok, but it's off a bit on TI measurements. I intended to open it up and get things up to spec, but never finished. It does have one intermittant BNC on the front panel that I haven't re-soldered yet. I'm not sure what the current prices are, but I know what I paid for it. How about $100 (less than I paid) plus shipping? Continental US only, please. I'll even throw in a fan that I was going to mount on the back heatsink. PM me. No need to clog up the list. Joe Gray W5JG ___ 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.
