Re: [time-nuts] float chargers for oscillator backup power
In message 6c69adeb-a4d8-4dee-a5d4-aec0fd164...@n1k.org, Bob Camp writes: HI We seem to have drifted a bit. This started out as a supply for the Z3xxx Lucent GPSDO’s. [...] Which, being telco material, is likely built to work exactly the way I described: An unclean, unregulated DC bus, and an internal DC/DC converter to clean it up and isolate it. I thought we were talking 'naked' OCXOs. One interesting setup I've seen, and which I'm contemplating next time I renovate my DC supply is this: * 30V power supply powers DC bus through diode. * Battery, also diode to DC bus * Bulk charger for filling up battery after discharge, turns once current decreases to setpoint. * Per battery DC/DC converters from the DC bus does float-charge. The two main points to this is that you can use a heavy duty bulkcharger, without paying for its losses in float-mode, and that each battery (if you have more than one) gets optimal float-charge regulation. -- 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] HP 5370, 5371, 5372, 5373
In message capxix5r0jdjynjytatfmcvfrhnt_ei0md26dtbcvuqeosp0...@mail.gmail.com , Stewart Cobb writes: Are they actually successor units? Are they upward-compatible with the 5370? Are they more accurate, or less accurate? Is there anything that a 5370 can do that the later units can't? They are much more than the 5370, but the single shot resolution is only 200ps (HP5370: 20ps) My best suggestion is to download the manual from the company formerly known as HP and read it. The main attraction in time-nut land is that they can do zero-deadtime measurement series. It's too bad they didn't build in a full ADEV(tau) plot function in them (at least the 5372A doesn't have it). I guess one could spend a winter adding the code and burn a new set of eproms, but I've never missed it that much. -- 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] Fwd: Re: Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A, Z3811A, Z3812...
when comparing bottom sides of ref0 and ref1 boards IC U207 near antenna input of ref1 seems to be missing. Goetz Original-Nachricht Betreff: Re: [time-nuts] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A, Z3811A, Z3812... Datum: Sun, 26 Oct 2014 22:24:29 + Von: Anthony Roby ar...@antamy.com Antwort an: Discussion of precise time and frequency measurement time-nuts@febo.com An: Discussion of precise time and frequency measurement time-nuts@febo.com Hal - there's nothing coming out of those connectors. I'll explore again once I can get my GPS connected to the unit and see if that changes anything. -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Hal Murray Sent: Sunday, October 26, 2014 4:11 PM To: Bob Stewart; Discussion of precise time and frequency measurement Cc: hmur...@megapathdsl.net Subject: Re: [time-nuts] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A, Z3811A, Z3812... b...@evoria.net said: Thanks for more pics. Was there any indication of where the 10MHz gets its signal? Could you see a trace, or did I miss that in the pics? I'm a bit too ham-fisted to go prodding around in mine, so I've left it closed after an initial urge to see the top of the board. If you look carefully at the pictures showing the bottom of the connector area on the 10 MHz and Antenna connectors you can see that the connectors don't share any mounting/connecting holes on the PCB. If you want 10 MHz out of the unit with the GPS module, you can get it from the center pin of the unused connector. (You may have to add other parts to get 10 MHz over there.) An alternative migh be to move the antenna connector on the GPS module from the bottom to the top, then use a pigtail lead to the panel. That may not work. From the pictures, it looks like power to the antenna is added to the trace on the bottom of the board. -- These are my opinions. 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 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] [Little OT now]Re: Cheap Frequency chip with serial output
The Teensy 3 can be programmed using the Arduino software. It's just a better Arduino, that's it. But you say you have a PI. Why not use that? send your final RF to a zero crossing detector then to a counter in the PI. I expect the PI does not have a counter, nor I would know how to set it up. Examples I found are in the 1MHz max range. Do you know which is the upper limit for it? ___ 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] float chargers for oscillator backup power
Hi Based on reports on the earlier Z3xxx’s , I would be careful about the low end of that supply range. There’s still way more range than you would ever need … Bob On Oct 26, 2014, at 11:42 PM, Bob Stewart b...@evoria.net wrote: Hi Bob, The little brick says it's happy with 18-36V. Bob From: Bob Camp kb...@n1k.org To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, October 26, 2014 10:37 PM Subject: Re: [time-nuts] float chargers for oscillator backup power HI We seem to have drifted a bit. This started out as a supply for the Z3xxx Lucent GPSDO’s. In those units, you have a 24 volt switcher that is driven off of the battery or linear supply. Since it’s designed as an isolated supply, I doubt the switcher in the GPSDO is looking for a very clean input. The same is true of it’s need for a tightly regulated input. Yes it’s efficiency will vary a bit with input and so will heat in the box. Still, not a real big deal if the voltage drops a volt or so when you go onto backup. The GPS is still running to keep everything lined up. How fast to you need to re-charge the battery bank? For me, not very fast. To keep the batteries healthy, maybe a bit faster than I would like. Lower charge current is another reason to go with a smaller battery if you can get away with it. 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 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 5370, 5371, 5372, 5373
If you making a list of HP TIAs, don't forget the E1470A -pete On Sun, Oct 26, 2014 at 10:05 PM, Stewart Cobb stewart.c...@gmail.com wrote: This list has a lot of discussion of HP 5370 time-interval counters, including the BeagleBone CPU upgrade. The usual sources seem to have HP 5371, 5372, and 5373 units available as well. From the profession of model numbers, and the cosmetics of the front panels, one might assume that these are successor units to the 5370. Are they actually successor units? Are they upward-compatible with the 5370? Are they more accurate, or less accurate? Is there anything that a 5370 can do that the later units can't? Cheers! --Stu ___ 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] [Little OT now]Re: Cheap Frequency chip with serial output
On Mon, Oct 27, 2014 at 4:29 AM, Giuseppe Marullo giuse...@marullo.it wrote: The Teensy 3 can be programmed using the Arduino software. It's just a better Arduino, that's it. But you say you have a PI. Why not use that? send your final RF to a zero crossing detector then to a counter in the PI. I expect the PI does not have a counter, nor I would know how to set it up. Examples I found are in the 1MHz max range. Do you know which is the upper limit for it? Don't know much about PI. if it will count to 1MHz them place a divide by 30 hardware chip in front of the PI.You will still get good enough resolution for tuning an old tube based radio. -- Chris Albertson Redondo Beach, California ___ 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] Cheap Frequency chip with serial output
Rather than read the bandswitch, a very common ham radio solution is to have the frequency counter read both the VFO and the crystal oscillator frequency and do the math with the last IF offset as part of the equation. At least one unit can also reads the BFO frequency. Although the low end PIC only has one counter, some gating can allow it to sequentially read the VFO, crystal oscillator, and BFO and then do the math. The AADE DFD2 is pretty sweet but they aren't currently selling the unit. Still it is the right way to do it. http://www.aade.com/dfd2.htm Tim N3QE On Sat, Oct 25, 2014 at 10:26 PM, Giuseppe Marullo giuse...@marullo.it wrote: Hello, just wanted to know if there is any very cheap pre programmed pic or something similar to get frequency of a Yaesu FT-102 radio. I need it to know its frequency, either the VFO alone (sub 6MHz) or possibly its real rx and tx frequency (up to 30MHz). Using the VFO would be easier but then I will have to probe the mechanical band commutator. I know Arduino could be a solution, just wanted to know if something smaller is available, possibly with rs232. TIA Giuseppe Marullo IW2JWW - JN45RQ ___ 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] 10MHz Rubidium reference source for frequency
Chris, I’m curious how you have the PLL set up for the 5680 and GPS. Do you have any schematics, docs, etc? I’m currently building a GPSDO based on James Miller’s design, and have a separate box with a 5680 in it (also grabbed from eBay for $40, since it “wouldn’t lock”, which was a simple fix). Thanks! -Ryan Stasel On Oct 26, 2014, at 6:51 PM, Chris Albertson albertson.ch...@gmail.com wrote: On Sun, Oct 26, 2014 at 2:05 PM, Karen Tadevosyan ra3...@mail.ru wrote: I hope to use homemade GPSDO for the rubidium oscillator calibration. You can save a little if you build a GPS disciplined Rb. It is just like building a GPSDO but you use the Rb in place of the OCXO. Saves money and I think gives better results because you do not have to transfer frequency from the crystal to the Rb. Unless you need the OCXO for some other reason. I was luck to have bought the FE5680 back when they were $35 each. They work well enough for my 10 digit frequency counter. -- Chris Albertson Redondo Beach, California ___ 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] 10MHz Rubidium reference source for frequency counter
Bert, Thank you for the interesting GPSDO/FE5680A proposal. I will contact you off list. Karen, ra3apw Date: Sun, 26 Oct 2014 17:22:45 -0400 From: ewkeh...@aol.com Karen To a large degree it depends on what you want to use it for. HP 5065 is considered top of the line and PRS 10 is a very nice Rb but lately I have seen lamp oscillator failures. I like FRK, well documented easy to modify and if done right super performance. As part of a GPSDO project using the FE 5680A that my Swiss friend Juerg and I have worked on for a year and is now in Beta test is also an alternative. We are done with FE 5680A so Juerg has his along with a GPSDO for sale. If you want a affordable Rb that has GPS control that is an alternative. Unit has less than 6 month running time so like new. Bert Kehren in Miami ___ 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] 10MHz Rubidium reference source for frequency counter
John, Thank you for the links (I visited few times before) and your recommendations. Really I am looking for a source with a good short range stability performance between 1 and 10 seconds. I will prepare additional description of my task with more details shortly ... Special Thanks for your TimeLab software which I use for ADEV and PN measurements. Karen, ra3apw Date: Sun, 26 Oct 2014 14:28:24 -0700 From: John Miles j...@miles.io Can I have your recommendation regarding a choice of 10 MHz rubidium source (available now on eBay like FE-5680; LPRO-101; LPFRS; FRS etc.) as a reference signal for my frequency counter Pendulum CNT-91. You might take a look at the plots at http://www.ke5fx.com/rb.htm if you haven't already, and also at http://febo.com/pages/oscillators/rubes/ . These will give you an idea what to expect from some of the popular Rb models. The PRS10 mentioned by Said is a great choice for long-term measurements, but it's also the most expensive of the ones you are likely to find on the surplus market. Interestingly, if you want the best performance between 1 and 10 seconds the PRS10 is actually the worst of the ones I measured. But the CNT-91 probably will not be able to see the difference, since its single-shot resolution is a bit worse than the HP 5370B counter (see attached plot). Caveats: 1) No rubidium standard will give its best long-term performance until it has been allowed to run undisturbed for at least a few days. 2) These plots shouldn't be taken too seriously because of the (very) small number of examples tested under inconsistent environmental conditions. -- john, KE5FX Miles Design LLC ___ 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] 10MHz Rubidium reference source for frequencycounter
Really I am looking for a source with a good short range stability performance between 1 and 10 seconds. If that is your goal, I'm not sure a cheap rubidium is necessary, or even a good choice. Many plain OCXO have better phase noise and better stability over tau 1 to 10 seconds. Also for this you may not need a GPSDO. That will give you better absolute accuracy, but it may not improve short-term stability. In fact many GPSDO make stability worse from, say, tau 10 to 100 seconds as a byproduct of making stability better for tau 1000+ seconds. Your frequency counter is superb; the Pendulum CNT-91 is my favorite. Can you tell us what you are actually trying to measure? I'm a little confused by the use of CNT-91, eBay rubidium, GPSDO, and good 1 - 10 second stability all in the same sentence. /tvb ___ 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] 10MHz Rubidium reference source for frequency counter
Hi Charles: The SRS PRS-10 is based on their 10 MHz SC-10 oscillator. This is what I installed in the Gibbs rack box and made use of it's the power supplies and added down counters to get a 1 PPS output. http://www.thinksrs.com/products/SC10.htm There are options for phase noise and aging and I suspect these same options could be used when ordering the PRS-10. Maybe Tom has data on some of the SC-10 oscillators? Mail_Attachment -- Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html http://www.prc68.com/I/DietNutrition.html Charles Steinmetz wrote: Karen wrote: Really I am looking for a source with a good short range stability performance between 1 and 10 seconds. I concur with everything Tom wrote. If that is your goal, the best you are likely to do is with a good, free-running (non-disciplined) OCXO. That will have the best stability you can get (short of a hydrogen maser) from 0.1 seconds to ~100 seconds. For the convenience of having automatic drift correction, many of us use GPSDOs and turn off the disciplining before making measurements. I might consider a PRS10 as an alternative, but certainly no other compact Rb, disciplined or otherwise. Even the rack-mount HP 5065 can't beat a good free-running OCXO. Many of the compact Rb units (and especially the FE5680) have nasty output waveforms with many spurs. Best regards, Charles ___ 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] 10MHz Rubidium reference source for frequency counter
Many thanks for all your recommendations. Let me provide more details for understanding of my task. I am playing with a GPSDO project on base of uBlox NEO-7M (http://www.ra3apw.ru/ublox-neo-7m-ocxo-gpsdo/) - sorry, text in Russian. One of the main step – ADEV measurement of a developed GPSDO. My ADEV measure stand consists of a frequency counter Pendulum CNT-91 with TimeBase option 19 + GPIB interface + KE5FX TimeLab software (TNX again John). As option for CNT-91’s reference source I can use a homemade GPSDO on base of G3RUH design. IMHO, in this condition a frequency stability of my GPSDO project should be higher than a stability of CNT-91’s reference OCXO. Taking into account that rubidium source has a better short range stability than OCXO or GPSDO I hope to find an external rubidium as 10 MHz reference source instead of internal OCXO of counter. If my reasoning is not right could you please correct them as I am not an expert in this area. Karen, ra3apw Date: Sun, 26 Oct 2014 14:45:00 -0700 From: Brooke Clarke bro...@pacific.net Hi Karen: The ones you mention are all stand alone Rb oscillators that need to be calibrated to set their frequency. This was the historical way that crystal oscillators were calibrated every year or so. The great advantage of Rb over crystal oscillators is that their drift is specified in months instead of days. A much better - more modern idea - is the GPS Disciplined Oscillator (GPSDO). It keeps the oscillator calibrated in real time. A popular crystal based GPSDO is the Trimble ThunderBolt: http://www.prc68.com/I/ThunderBolt.shtml Another crystal based GPSDO is the HP Z3805: http://www.prc68.com/I/Z3805A.html There are many more commercial GPSDOs and this list has discussions that show they can be a do it yourself project for under maybe $10, but require a number of sophisticated skills. I have the just released LTE-Lite GPSDO Evaluation Kit with 10MHz TCXO on order. Seems to offer good performance for the dollar. http://www.ebay.com/itm/171504585820 The only advantage of a Rb GPSDO over a crystal GPSDO is for the case where the GPS updating has not happened for some time. This might be due to a power failure lasting some days or that the oscillator will be used where there's no GPS access and it only gets calibrated then used much later. The Stanford Research PRS-10 Rb oscillator can be used stand alone where it time stamps an external 1 Pulse Per Second input, or as part of a GPSDO where an external GPS receiver supplies it with a 1 PPS input. http://www.prc68.com/I/PRS10.shtml The Thunderbolt can be custom modified to drive an external Rb oscillator, like the ones you mentioned, but that requires some technical sophistication. Note the ThunderBolt and Z3805 are complete GPSDOs in a box, just connect power and a GPS antenna. The PRS-10 requires an external GPS receiver and antenna. A a practical matter that means it's more work to maintain the PRS-10 because there's more opportunity for problems like disconnecting a cable. PS Stanford Research offered a version of their SR620 Time Interval counter that included a Rb oscillator (not a GPSDO) that some government agencies purchased, but for normal use you really don't need a Rb oscillator, so the CNT-91R appears to be a similar way so sell it to a government with a lot of money to spare. So don't feel pressured to use an Rb oscillator. http://www.prc68.com/I/TandFTE.shtml#SR620 Mail_Attachment -- Have Fun, Brooke Clarke, N6GCE http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html http://www.prc68.com/I/DietNutrition.html ___ 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] 10MHz Rubidium reference source for frequency counter
Karen wrote: Really I am looking for a source with a good short range stability performance between 1 and 10 seconds. I concur with everything Tom wrote. If that is your goal, the best you are likely to do is with a good, free-running (non-disciplined) OCXO. That will have the best stability you can get (short of a hydrogen maser) from 0.1 seconds to ~100 seconds. For the convenience of having automatic drift correction, many of us use GPSDOs and turn off the disciplining before making measurements. I might consider a PRS10 as an alternative, but certainly no other compact Rb, disciplined or otherwise. Even the rack-mount HP 5065 can't beat a good free-running OCXO. Many of the compact Rb units (and especially the FE5680) have nasty output waveforms with many spurs. Best regards, Charles ___ 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] 10MHz Rubidium reference source for frequency counter
Karen, a good double oven OCXO such as Morion etc will give you much better short term stability than most Rudidiums can give you. By a factor of 10 or even 100 sometimes below 10s measurement interval. The Rb's are better anywhere from 100s to many 1000 seconds. bye, Said In a message dated 10/27/2014 13:57:14 Pacific Daylight Time, ra3...@mail.ru writes: Many thanks for all your recommendations. Let me provide more details for understanding of my task. I am playing with a GPSDO project on base of uBlox NEO-7M (http://www.ra3apw.ru/ublox-neo-7m-ocxo-gpsdo/) - sorry, text in Russian. One of the main step – ADEV measurement of a developed GPSDO. My ADEV measure stand consists of a frequency counter Pendulum CNT-91 with TimeBase option 19 + GPIB interface + KE5FX TimeLab software (TNX again John). As option for CNT-91’s reference source I can use a homemade GPSDO on base of G3RUH design. IMHO, in this condition a frequency stability of my GPSDO project should be higher than a stability of CNT-91’s reference OCXO. Taking into account that rubidium source has a better short range stability than OCXO or GPSDO I hope to find an external rubidium as 10 MHz reference source instead of internal OCXO of counter. If my reasoning is not right could you please correct them as I am not an expert in this area. Karen, ra3apw Date: Sun, 26 Oct 2014 14:45:00 -0700 From: Brooke Clarke bro...@pacific.net Hi Karen: The ones you mention are all stand alone Rb oscillators that need to be calibrated to set their frequency. This was the historical way that crystal oscillators were calibrated every year or so. The great advantage of Rb over crystal oscillators is that their drift is specified in months instead of days. A much better - more modern idea - is the GPS Disciplined Oscillator (GPSDO). It keeps the oscillator calibrated in real time. A popular crystal based GPSDO is the Trimble ThunderBolt: http://www.prc68.com/I/ThunderBolt.shtml Another crystal based GPSDO is the HP Z3805: http://www.prc68.com/I/Z3805A.html There are many more commercial GPSDOs and this list has discussions that show they can be a do it yourself project for under maybe $10, but require a number of sophisticated skills. I have the just released LTE-Lite GPSDO Evaluation Kit with 10MHz TCXO on order. Seems to offer good performance for the dollar. http://www.ebay.com/itm/171504585820 The only advantage of a Rb GPSDO over a crystal GPSDO is for the case where the GPS updating has not happened for some time. This might be due to a power failure lasting some days or that the oscillator will be used where there's no GPS access and it only gets calibrated then used much later. The Stanford Research PRS-10 Rb oscillator can be used stand alone where it time stamps an external 1 Pulse Per Second input, or as part of a GPSDO where an external GPS receiver supplies it with a 1 PPS input. http://www.prc68.com/I/PRS10.shtml The Thunderbolt can be custom modified to drive an external Rb oscillator, like the ones you mentioned, but that requires some technical sophistication. Note the ThunderBolt and Z3805 are complete GPSDOs in a box, just connect power and a GPS antenna. The PRS-10 requires an external GPS receiver and antenna. A a practical matter that means it's more work to maintain the PRS-10 because there's more opportunity for problems like disconnecting a cable. PS Stanford Research offered a version of their SR620 Time Interval counter that included a Rb oscillator (not a GPSDO) that some government agencies purchased, but for normal use you really don't need a Rb oscillator, so the CNT-91R appears to be a similar way so sell it to a government with a lot of money to spare. So don't feel pressured to use an Rb oscillator. http://www.prc68.com/I/TandFTE.shtml#SR620 Mail_Attachment -- Have Fun, Brooke Clarke, N6GCE http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html http://www.prc68.com/I/DietNutrition.html ___ 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] 10MHz Rubidium reference source for frequency
On Mon, Oct 27, 2014 at 9:10 AM, Ryan Stasel rsta...@uoregon.edu wrote: Chris, I’m curious how you have the PLL set up for the 5680 and GPS. Do you have any schematics, docs, etc? I used a simplified version of the design posted by Lars Walenius. Simplified in that I took out 90% of the software using only the few lines that were needed. The controller is basically PID but with VERY low gain. Some one who is smarter might be able to make it settle faster but I didn't care. Phase detector is a HC4046 chip The output is filtered with LC filter then read using ADC on Arduino. The PID tries to keep this value are some arbitrary constant value Lars' idea was to make this as simple as could be. Mine was to make it even more simple. I found I could not remove any of his hardware parts but I could make the software much smaller. -- Chris Albertson Redondo Beach, California ___ 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] 10MHz Rubidium reference source for frequencycounter
Thanks for the explanation. In this case you should buy both a cheap Rb and good OCXO from eBay. This will allow you to explore the resolution of your CNT-91 as well as make several pair-wise plots using TimeLab. Remember that no one frequency reference will suite all occasions. Sometimes the ones with best phase noise do not have the best ADEV. The ones with best short-term stability may not have the best long-term stability. The one with best long-term stability (e.g., sawtooth corrected/GPS 1PPS) needs to be sampled over long time scales. So a variety of time/frequency sources is nice to have. A NEO-7M GPSDO sounds like a fun project. I agree with Said that a Morion would be a nice oscillator to discipline. The Rb may be useful to validate the mid-term performance of the GPSDO and help determine the tuning of your algorithms. /tvb - Original Message - From: Karen Tadevosyan ra3...@mail.ru To: time-nuts@febo.com Sent: Monday, October 27, 2014 1:01 PM Subject: Re: [time-nuts] 10MHz Rubidium reference source for frequencycounter Many thanks for all your recommendations. Let me provide more details for understanding of my task. I am playing with a GPSDO project on base of uBlox NEO-7M (http://www.ra3apw.ru/ublox-neo-7m-ocxo-gpsdo/) - sorry, text in Russian. One of the main step – ADEV measurement of a developed GPSDO. My ADEV measure stand consists of a frequency counter Pendulum CNT-91 with TimeBase option 19 + GPIB interface + KE5FX TimeLab software (TNX again John). As option for CNT-91’s reference source I can use a homemade GPSDO on base of G3RUH design. IMHO, in this condition a frequency stability of my GPSDO project should be higher than a stability of CNT-91’s reference OCXO. Taking into account that rubidium source has a better short range stability than OCXO or GPSDO I hope to find an external rubidium as 10 MHz reference source instead of internal OCXO of counter. If my reasoning is not right could you please correct them as I am not an expert in this area. Karen, ra3apw Date: Sun, 26 Oct 2014 14:45:00 -0700 From: Brooke Clarke bro...@pacific.net Hi Karen: The ones you mention are all stand alone Rb oscillators that need to be calibrated to set their frequency. This was the historical way that crystal oscillators were calibrated every year or so. The great advantage of Rb over crystal oscillators is that their drift is specified in months instead of days. A much better - more modern idea - is the GPS Disciplined Oscillator (GPSDO). It keeps the oscillator calibrated in real time. A popular crystal based GPSDO is the Trimble ThunderBolt: http://www.prc68.com/I/ThunderBolt.shtml Another crystal based GPSDO is the HP Z3805: http://www.prc68.com/I/Z3805A.html There are many more commercial GPSDOs and this list has discussions that show they can be a do it yourself project for under maybe $10, but require a number of sophisticated skills. I have the just released LTE-Lite GPSDO Evaluation Kit with 10MHz TCXO on order. Seems to offer good performance for the dollar. http://www.ebay.com/itm/171504585820 The only advantage of a Rb GPSDO over a crystal GPSDO is for the case where the GPS updating has not happened for some time. This might be due to a power failure lasting some days or that the oscillator will be used where there's no GPS access and it only gets calibrated then used much later. The Stanford Research PRS-10 Rb oscillator can be used stand alone where it time stamps an external 1 Pulse Per Second input, or as part of a GPSDO where an external GPS receiver supplies it with a 1 PPS input. http://www.prc68.com/I/PRS10.shtml The Thunderbolt can be custom modified to drive an external Rb oscillator, like the ones you mentioned, but that requires some technical sophistication. Note the ThunderBolt and Z3805 are complete GPSDOs in a box, just connect power and a GPS antenna. The PRS-10 requires an external GPS receiver and antenna. A a practical matter that means it's more work to maintain the PRS-10 because there's more opportunity for problems like disconnecting a cable. PS Stanford Research offered a version of their SR620 Time Interval counter that included a Rb oscillator (not a GPSDO) that some government agencies purchased, but for normal use you really don't need a Rb oscillator, so the CNT-91R appears to be a similar way so sell it to a government with a lot of money to spare. So don't feel pressured to use an Rb oscillator. http://www.prc68.com/I/TandFTE.shtml#SR620 Mail_Attachment -- Have Fun, Brooke Clarke, N6GCE http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html http://www.prc68.com/I/DietNutrition.html ___ 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] 10MHz Rubidium reference source for frequency counter
Hello Karen, I think you are confusing and/or mixing the terms stability and accuracy with respect to your project. It all depends upon your measurement period and the property being measured. A GPSDO will never beat a truly, very high quality OCXO on a short term basis in the stability department. For that matter most Rubidium's that you find on auction sites won't either. Accuracy, on the other hand, is another matter. A good and properly setup GPSDO will provide long term accuracy (years) with a Rubidium (months), calibrated, in second place and the very high quality OCXO (up to days) is last, again, with respect to accuracy. BillWB6BNQ Karen Tadevosyan wrote: Many thanks for all your recommendations. Let me provide more details for understanding of my task. I am playing with a GPSDO project on base of uBlox NEO-7M (http://www.ra3apw.ru/ublox-neo-7m-ocxo-gpsdo/) - sorry, text in Russian. One of the main step – ADEV measurement of a developed GPSDO. My ADEV measure stand consists of a frequency counter Pendulum CNT-91 with TimeBase option 19 + GPIB interface + KE5FX TimeLab software (TNX again John). As option for CNT-91’s reference source I can use a homemade GPSDO on base of G3RUH design. IMHO, in this condition a frequency stability of my GPSDO project should be higher than a stability of CNT-91’s reference OCXO. Taking into account that rubidium source has a better short range stability than OCXO or GPSDO I hope to find an external rubidium as 10 MHz reference source instead of internal OCXO of counter. If my reasoning is not right could you please correct them as I am not an expert in this area. Karen, ra3apw Date: Sun, 26 Oct 2014 14:45:00 -0700 From: Brooke Clarke bro...@pacific.net Hi Karen: The ones you mention are all stand alone Rb oscillators that need to be calibrated to set their frequency. This was the historical way that crystal oscillators were calibrated every year or so. The great advantage of Rb over crystal oscillators is that their drift is specified in months instead of days. A much better - more modern idea - is the GPS Disciplined Oscillator (GPSDO). It keeps the oscillator calibrated in real time. A popular crystal based GPSDO is the Trimble ThunderBolt: http://www.prc68.com/I/ThunderBolt.shtml Another crystal based GPSDO is the HP Z3805: http://www.prc68.com/I/Z3805A.html There are many more commercial GPSDOs and this list has discussions that show they can be a do it yourself project for under maybe $10, but require a number of sophisticated skills. I have the just released LTE-Lite GPSDO Evaluation Kit with 10MHz TCXO on order. Seems to offer good performance for the dollar. http://www.ebay.com/itm/171504585820 The only advantage of a Rb GPSDO over a crystal GPSDO is for the case where the GPS updating has not happened for some time. This might be due to a power failure lasting some days or that the oscillator will be used where there's no GPS access and it only gets calibrated then used much later. The Stanford Research PRS-10 Rb oscillator can be used stand alone where it time stamps an external 1 Pulse Per Second input, or as part of a GPSDO where an external GPS receiver supplies it with a 1 PPS input. http://www.prc68.com/I/PRS10.shtml The Thunderbolt can be custom modified to drive an external Rb oscillator, like the ones you mentioned, but that requires some technical sophistication. Note the ThunderBolt and Z3805 are complete GPSDOs in a box, just connect power and a GPS antenna. The PRS-10 requires an external GPS receiver and antenna. A a practical matter that means it's more work to maintain the PRS-10 because there's more opportunity for problems like disconnecting a cable. PS Stanford Research offered a version of their SR620 Time Interval counter that included a Rb oscillator (not a GPSDO) that some government agencies purchased, but for normal use you really don't need a Rb oscillator, so the CNT-91R appears to be a similar way so sell it to a government with a lot of money to spare. So don't feel pressured to use an Rb oscillator. http://www.prc68.com/I/TandFTE.shtml#SR620 Mail_Attachment -- Have Fun, Brooke Clarke, N6GCE http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html http://www.prc68.com/I/DietNutrition.html ___ 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.
