[time-nuts] multiple timing
Ran across the following; has 16 counter-timers and USB interface. http://accesio.com/go.cgi?p=../usb-oem/usb-ctr-15.html Might do the job. Don -- Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind. R. Bacon If you don't know what it is, don't poke it. Ghost in the Shell Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.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] FPGA counter/timer
Some time ago we initiated thoughts about development of a FPGA setup to replace the HP stuff. Here it is, I think: http://vigo.com.pl/index.php/en/english_menu/products/measurement_instruments/time_frequency_counters I'm trying to get a price. Don -- Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind. R. Bacon If you don't know what it is, don't poke it. Ghost in the Shell Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.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] Lucent RFTG-m-XO GPSDO
I have been playing with one of these units, and noticed that there has been some discussion on them before on this list, so I wondered if anyone might have any suggestions. Basically, the unit powers up correctly, but the No GPS LED never goes off - this obviously could be because it's broken or doesn't like my antenna, but with some of these telecom GPSDOs you have to manually trigger a site survey if you move them to another location. Does anyone know if this Lucent box is like that? Everything else seems to be working - once the OK light comes on the 15MHz output is enbled, the No GPS LED goes from solid to blinking if you disconnect the antenna - it just doesn't want to get GPS lock. I suppose I could pull the Oncore board (a UT+ according to the label) out of it and test that on it's own - but I thiought I would see if maybe it's a known issue first. ___ 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] HP5065A digital clock update
Just finished rebuilding the digital clock, and all is well. The original clock IC was still good, so the display board stayed with minimal rework - only new interface and power system needed. Made a number of improvements: 1. Eliminated original power/interface board and clock setting buttons. 2. Isolated clock power common from chassis so no current through front panel. 3. Added electromagnetic shield surrounding entire module. All connections via feed-through caps. 4. Added local bypassing of LED currents at drivers and on clock IC power. 5. New power system with shunt regulator for LED power, making it a constant current load, to isolate the large step changes in segment and scan currents from the main supply. Also includes more filtering and fault protection. 6. Clock setting to be handled via 1 PPS signal - sped up or stopped according to controls to be added inside center compartment, accessible from front panel. 7. Added dim mode - display still visible when operating on battery backup mode (takes 15 mA extra). Operating characteristics: Input power: 12 VDC (regulated), approx 320 mA constant on AC power, 40 mA on battery backup (dim), 25 mA (blank), battery read button still functional for normal intensity. 1 PPS input: TTL level, high impedance, 0-100 kHz. Mode control input: AC on = +12V, AC off/fail = 0V. Ed ___ 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] the care and feeding of LPRO's
Hi The basic answer is: 1) Power them off of something stable around 18 to 19 volts. Anything higher just heats them up without doing anything useful. 2) Put a heat sink on them. You want to get the base plate to below 50C. Without a heat sink they get warm enough to significantly shorten their life. You can indeed get fancy and control the heat sink temperature. They are sensitive to magnetic field, barometric temperature, and humidity as well as voltage and temperature. Keeping them on tends to help with humidity. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Eric Garner Sent: Friday, October 07, 2011 11:24 AM To: Discussion of precise time and frequency measurement Subject: [time-nuts] the care and feeding of LPRO's Up to this point in my Nuttery I've been messing around with various GPSDOs. I just bought an LPRO off of Ebay. It hasn't arrived yet but I wanted to start getting it ready to hookup and play with. I have several questions that I couldn't find answers to in the archives. 1. has any work been done on optimal power supply design to run these beasties? I'm initially going to run it off of my (very quiet) bench supply but long term I would like to put it in a nice box with it's own supply. how much does power supply noise affect long term stability/noise? 2. what sort of thermal tricks can I do to optimize performance (keep away from drafts or add thermal mass) 3. any other tricks? thanks. -- --Eric _ Eric Garner ___ 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] the care and feeding of LPRO's
Eric, the power supply quality is not critical. The LPRO (like most other Rb's) has an internal switching power supply, so the wide tolerance in the primary power source voltage. I found other Rb's to be quite sensitive to vibrations, but when they are in a box, with a decent PS (I use an universal portable PC PS, the variety that may be programmed by means of a resistor in a plug) and an heat sink they are happy. Marco IK1ODO ___ 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] FPGA counter/timer
You do realize that around that same time of some time ago the T3000 goodies were already there, just waiting for you to buy them. ;) I just checked, and the T3100 datasheet I have from last year even has the same md5sum as the one currently on their website. It would be interesting to know what kind of price they currently go for. regards, Fred From: Don Latham d...@montana.com To: time nuts time-nuts@febo.com Sent: Friday, October 7, 2011 9:11 AM Subject: [time-nuts] FPGA counter/timer Some time ago we initiated thoughts about development of a FPGA setup to replace the HP stuff. Here it is, I think: http://vigo.com.pl/index.php/en/english_menu/products/measurement_instruments/time_frequency_counters I'm trying to get a price. Don -- Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind. R. Bacon If you don't know what it is, don't poke it. Ghost in the Shell Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.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] the care and feeding of LPRO's
There are lots of ways you can unintentionally affect a device like an LPRO. For instance, suppose the internal power supply dissipates a different amount of heat depending on the input supply voltage. This could cause the oven to momentarily shift its internal temperature a small amount... which may show up as a frequency shift. Or suppose the current change due to changing input voltage causes a magnetic disturbance that shifts frequency? We're time-nuts. We are trying to get more from these devices than the manufacturer ever intended. -Chuck Harris Marco IK1ODO -2 wrote: Eric, the power supply quality is not critical. The LPRO (like most other Rb's) has an internal switching power supply, so the wide tolerance in the primary power source voltage. I found other Rb's to be quite sensitive to vibrations, but when they are in a box, with a decent PS (I use an universal portable PC PS, the variety that may be programmed by means of a resistor in a plug) and an heat sink they are happy. Marco IK1ODO ___ 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] the care and feeding of LPRO's
On 07/10/11 19:01, Chuck Harris wrote: There are lots of ways you can unintentionally affect a device like an LPRO. For instance, suppose the internal power supply dissipates a different amount of heat depending on the input supply voltage. This could cause the oven to momentarily shift its internal temperature a small amount... which may show up as a frequency shift. Or suppose the current change due to changing input voltage causes a magnetic disturbance that shifts frequency? We're time-nuts. We are trying to get more from these devices than the manufacturer ever intended. So you let in normal mains into you lab? :-) If you have linear supplies, you want to 1) Steer voltage to be within a tight spec. This will remove variation in burned power in the linear supplies. 2) Run at higher frequency, say 400 Hz, to create smaller ripple after caps, 3) With 400 Hz the lower ripple will increase the effective voltage after rectification and caps, so the mains voltage can now be reduced resulting in even less power dissapation from the power-supply. No, I haven't done this, but I realized this after fiddling around with supplies and verified the ideas with a friend of mine designing supplies all the time. He also pointed out that many switch supplies tend to run better when the supply voltage is on the low side of things. So, there is things to do if you really want to control your environment. Now, how many labs log their mains voltage and correlate frequency deviations to that? 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] the care and feeding of LPRO's
No, I haven't done this, but I realized this after fiddling around with supplies and verified the ideas with a friend of mine designing supplies all the time. He also pointed out that many switch supplies tend to run better when the supply voltage is on the low side of things. Better? Lower input voltage = higher input current. Resistive losses in the primary side are R*I^2.. Lower input voltage = hotter, all other things being equal. ___ 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] the care and feeding of LPRO's
fortunately, everything in the lab(basement) is on UPSs so in theory the input voltages to the equipment should be pretty constant and I was already planning on using a linear supply. as far as magnetic disturbances go, what is a reasonable precaution short of making a muMetal box? On Fri, Oct 7, 2011 at 11:04 AM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 07/10/11 19:01, Chuck Harris wrote: There are lots of ways you can unintentionally affect a device like an LPRO. For instance, suppose the internal power supply dissipates a different amount of heat depending on the input supply voltage. This could cause the oven to momentarily shift its internal temperature a small amount... which may show up as a frequency shift. Or suppose the current change due to changing input voltage causes a magnetic disturbance that shifts frequency? We're time-nuts. We are trying to get more from these devices than the manufacturer ever intended. So you let in normal mains into you lab? :-) If you have linear supplies, you want to 1) Steer voltage to be within a tight spec. This will remove variation in burned power in the linear supplies. 2) Run at higher frequency, say 400 Hz, to create smaller ripple after caps, 3) With 400 Hz the lower ripple will increase the effective voltage after rectification and caps, so the mains voltage can now be reduced resulting in even less power dissapation from the power-supply. No, I haven't done this, but I realized this after fiddling around with supplies and verified the ideas with a friend of mine designing supplies all the time. He also pointed out that many switch supplies tend to run better when the supply voltage is on the low side of things. So, there is things to do if you really want to control your environment. Now, how many labs log their mains voltage and correlate frequency deviations to that? 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. -- --Eric _ Eric Garner ___ 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] the care and feeding of LPRO's
fortunately, everything in the lab(basement) is on UPSs so in theory the input voltages to the equipment should be pretty constant and I was already planning on using a linear supply. Be careful, there. Most consumer type UPSs are not line regulators. When there is sufficiently high line voltage they are completely out of the circuit and the line voltage is passed through to the output unaffected. They're usually not designed for continuous operation of the inverter circuit. There was a more in-depth discussion of this a while back in a thread about running 50 / 60 Hz clocks from a locked frequency source. One possibility, though, would be a ferroresonant line regulator, like a Sola transformer. If you can tolerate the acoustic noise and the high power dissipation they will do a somewhat decent job of reducing line fluctuations. IIRC the output is also not necessarily a sine wave (depends on the design). -John ___ 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] Measuring ADEV using TBolt-Tic tester
On 07/10/11 19:00, WarrenS wrote: Use the (J J) command to rezero the Phase plot (plus the cable delay if desired) and then read or adjust the Osc freq on the ppt plot. With LadyHeather's filter off (F D 0) useful resolution is about 1e-10 in one second, With the filter set to 10 sec (F D 10) useful resolution is near 1e-11 in well under one minute With the filter set to 100 sec, resolution is around 1e-11 in a few minutes. adding a trend line helps (G O L) Be a little careful here. Pre-filtering will scale white-noise ADEV linearly, please see the Power noise table I put in the ADEV wiki article: http://en.wikipedia.org/wiki/Allan_variance#Power-law_noise f_H is the system bandwidth and changing the pre-filtering you do change this property. The end result is that your h_2 amount of white phase noise is the same but only gives different ADEV values, and is not the result of improved noise floor. However, you can use various settings to separate between WPM and FPM noise levels. 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] the care and feeding of LPRO's
On 07/10/11 20:30, John Lofgren wrote: fortunately, everything in the lab(basement) is on UPSs so in theory the input voltages to the equipment should be pretty constant and I was already planning on using a linear supply. Be careful, there. Most consumer type UPSs are not line regulators. When there is sufficiently high line voltage they are completely out of the circuit and the line voltage is passed through to the output unaffected. They're usually not designed for continuous operation of the inverter circuit. There was a more in-depth discussion of this a while back in a thread about running 50 / 60 Hz clocks from a locked frequency source. Indeed. Even large UPSes usually run in bypass mode to save power. Actually running the DC to AC conversion isn't used much these days. It's much more difficult to kill my argument that most modern equipment run on switchers, which causes much less variation on power dissapation with supply voltage, but I was careful to talk about linear supplies... 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] Measuring ADEV using TBolt-Tic tester
I know that few of the GPS constellation satellites carry a Cs clock instead of the Rb one: is it possible to take advantage from this? I think not because Cs and Rb satellites are equally well steered but using the masking options of GPS receivers maybe that Cs clocks can help. On Fri, Oct 7, 2011 at 8:34 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 07/10/11 19:00, WarrenS wrote: Use the (J J) command to rezero the Phase plot (plus the cable delay if desired) and then read or adjust the Osc freq on the ppt plot. With LadyHeather's filter off (F D 0) useful resolution is about 1e-10 in one second, With the filter set to 10 sec (F D 10) useful resolution is near 1e-11 in well under one minute With the filter set to 100 sec, resolution is around 1e-11 in a few minutes. adding a trend line helps (G O L) Be a little careful here. Pre-filtering will scale white-noise ADEV linearly, please see the Power noise table I put in the ADEV wiki article: http://en.wikipedia.org/wiki/**Allan_variance#Power-law_noisehttp://en.wikipedia.org/wiki/Allan_variance#Power-law_noise f_H is the system bandwidth and changing the pre-filtering you do change this property. The end result is that your h_2 amount of white phase noise is the same but only gives different ADEV values, and is not the result of improved noise floor. However, you can use various settings to separate between WPM and FPM noise levels. Cheers, Magnus __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://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] the care and feeding of LPRO's
Magnus Danielson wrote: We're time-nuts. We are trying to get more from these devices than the manufacturer ever intended. So you let in normal mains into you lab? :-) Me personally? I don't worry much about little stuff like that, so I am more of a time-nut heretic. I did wire my house and shop in armored/shielded cable, however. It reduced the radiated 60Hz E-M fields quite a lot. -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] the care and feeding of LPRO's
On 10/7/11 11:16 AM, Eric Garner wrote: fortunately, everything in the lab(basement) is on UPSs so in theory the input voltages to the equipment should be pretty constant and I was already planning on using a linear supply. What kind of UPS? A static inverter? Most UPSes just feed the line through until it goes out of range, and then it switches (within 8-10 ms) to the output of the inverter. And even when on inverter, the output voltage regulation isn't all that hot, unless you've got a special inverter. A 5-10% variation in voltage from an inverter/UPS wouldn't be surprising.. (why should they try to do better.. the goal is to keep the equipment on, not serve as a voltage regulator) ___ 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] Measuring ADEV using TBolt-Tic tester
Very Important note, The above is NOT available directly from LadyHeather's ADEV plots (at least not yet - Mark is a revision coming?), What one needs to do is to log the Tbolt's Freq and Phase data at the 1 sec rate and then use that data with an external ADEV program such as Ulrich's Plotter or John's TimeLab. Note for TimeLab users. LH adds some extra comment data lines in it's log file that need to be manually removed before using the data file with some versions of TimeLab. I had a 'native' Thunderbolt driver in the old TI.EXE program that I could probably bring across to TimeLab without much trouble. It didn't work with the COM port directly, but with a Heather TCP/IP server. That means that it takes some extra work to set up since you have to run two programs, but it also means that you can run LH and TimeLab on the same Thunderbolt at the same time, with no need to monkey around with logfiles. I'll have a look at it to see if I can bring that code back from cold storage. . . . If you want even more accuracy, watch the PHASE change over a few days. This can check your best Primary Cs standard's frequency. Eventually a GPS clock will reach something like a flicker floor where the ADEV trace flattens out and stops decreasing over time. I don't really know where the flicker floor is on a Thunderbolt-class clock versus where it will be on a local cesium standard. The sigma-tau statistics for the more common HP 5061-era clocks were never really specified for periods more than a day, while at the same time, there don't seem to have been many long-term tests run on Thunderbolts and other GPS clocks to see where their performance flattens out. It would be good to see some more long-term trials. Said, do you have data for the long-term (multi-week) floors of the various Jackson Labs GPSDOs? Intuitively, I don't believe a GPSDO can outperform an HP 5071A-era clock over periods greater than a few hours. But it may be reasonable to benchmark 5061A-class standards with a good GPSDO setup. We really need some more data from trials lasting multiple weeks. -- john ___ 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] the care and feeding of LPRO's
I run my pcs on a double conversion true sine wave UPS. It is designed to run continuously. It converts to DC, which is easy to filter, then creates a voltage and frequency regulated sine wave. Modified sine is just a square wave. Complete junk. ___ 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] Measuring ADEV using TBolt-Tic tester
Magnus I probable was not very clear in my posting. (what else is new?) There where TWO completely different subjects, goals and techniques in the same Posting. #1 was how to Log data for valid ADEV plots. That takes setting the filter OFF for the reasons you state. The ADEV tau axes provides the filter function. Different subject altogether, the one you copied has NOTHING to do with ADEV plots or data. #2 was measuring and Plotting the AVERAGE frequency (Not ADEV) and to do that effectively, one uses LP filtered data. For Low pass filtering, can use LadyHeather's filter function and / or the trend line. By looking at the freq plot at different filter settings, one can see what type of noise is there. And as you point out, the noise type does make a difference to the improvement in resolution that is obtained. I was just giving some general values that are valid for my typical type of noise in my setup, which is mostly white over short time periods using lots of care. And yes can not be overstated, need to be carefull when taking and using data. ws * On 07/10/11 19:00, WarrenS wrote: Use the (J J) command to rezero the Phase plot (plus the cable delay if desired) and then read or adjust the Osc freq on the ppt plot. With LadyHeather's filter off (F D 0) useful resolution is about 1e-10 in one second, With the filter set to 10 sec (F D 10) useful resolution is near 1e-11 in well under one minute With the filter set to 100 sec, resolution is around 1e-11 in a few minutes. adding a trend line helps (G O L) Be a little careful here. Pre-filtering will scale white-noise ADEV linearly, please see the Power noise table I put in the ADEV wiki article: http://en.wikipedia.org/wiki/Allan_variance#Power-law_noise f_H is the system bandwidth and changing the pre-filtering you do change this property. The end result is that your h_2 amount of white phase noise is the same but only gives different ADEV values, and is not the result of improved noise floor. However, you can use various settings to separate between WPM and FPM noise levels. 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] Measuring ADEV using TBolt-Tic tester
You would first have to answer which are better to use for short term, Cs or Rb? (the answer is: a good OCXO) My guess is it does not mater, all are so much better than what is received by a Tbolt. And for long term where a Cs wins, they are disiplined/corrected in some way so it don't mater. ws * Azelio Boriani azelio.boriani at screen.it I know that few of the GPS constellation satellites carry a Cs clock instead of the Rb one: is it possible to take advantage from this? I think not because Cs and Rb satellites are equally well steered but using the masking options of GPS receivers maybe that Cs clocks can help. ___ 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] Measuring ADEV using TBolt-Tic tester
On Oct 7, 2011, at 3:32 PM, John Miles jmi...@pop.net wrote: Intuitively, I don't believe a GPSDO can outperform an HP 5071A-era clock over periods greater than a few hours. But it may be reasonable to benchmark 5061A-class standards with a good GPSDO setup. We really need some more data from trials lasting multiple weeks. Some test like these are on my list for this winter. I am planning to look at a Z3801A versus a couple of 5061 class units: one with a high stability tube that I think is in very good condition, and another with an FTS replacement tube of probably typical surplus quality. I can also add a TBolt into the mix. I'm hoping to lash up multiple 5334 counters in TIC mode so I can do several comparisons simultaneously. In an early test of the 004 tube vs. Z3801A over a week or so, I saw what looked like a floor in the 8e14 range. John ___ 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] Measuring ADEV using TBolt-Tic tester
Hi, As for the CS vs RB on orbit, the Elmer Perkins RBs on IIR are better out to a few days than CS on the older satellites. Anybody knows which clocks are in the new IIF-satellite on orbit? Any performance data published? -- Björn You would first have to answer which are better to use for short term, Cs or Rb? (the answer is: a good OCXO) My guess is it does not mater, all are so much better than what is received by a Tbolt. And for long term where a Cs wins, they are disiplined/corrected in some way so it don't mater. ws * Azelio Boriani azelio.boriani at screen.it I know that few of the GPS constellation satellites carry a Cs clock instead of the Rb one: is it possible to take advantage from this? I think not because Cs and Rb satellites are equally well steered but using the masking options of GPS receivers maybe that Cs clocks can help. ___ 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] Measuring ADEV using TBolt-Tic tester
John It would be great to have a direct Tbolt driver on TimeLab. Right now it is so much trouble and time to use it, it takes away of the great real time capabilities of TimeLab. According to Tom his really good Cs has an Flicker noise floor of almost 10 days using 4 ns rms for phase noise. A really good Tbolt set up will hold around 2 ns of phase noise, so I think that means the flicker noise floor of a Tbolt will surpass Tom's Best Cs after 5 to 20 days. From what I've seen it takes a few hours to a day to do better than the more average Cs. I have a plot showing a Tbolt GPSDO doing better than 1e-13 (which seems pretty typical of most Cs) over a day using a compensated LPRO. ws ** John Miles jmiles at pop.net Very Important note, The above is NOT available directly from LadyHeather's ADEV plots (at least not yet - Mark is a revision coming?), What one needs to do is to log the Tbolt's Freq and Phase data at the 1sec rate and then use that data with an external ADEV program such as Ulrich's Plotter or John's TimeLab. Note for TimeLab users. LH adds some extra comment data lines in it's log file that need to be manually removed before using the data file with some versions of TimeLab. I had a 'native' Thunderbolt driver in the old TI.EXE program that I could probably bring across to TimeLab without much trouble. It didn't work with the COM port directly, but with a Heather TCP/IP server. That means that it takes some extra work to set up since you have to run two programs, but it also means that you can run LH and TimeLab on the same Thunderbolt at the same time, with no need to monkey around with logfiles. I'll have a look at it to see if I can bring that code back from cold storage. . . . If you want even more accuracy, watch the PHASE change over a few days. This can check your best Primary Cs standard's frequency. Eventually a GPS clock will reach something like a flicker floor where the ADEV trace flattens out and stops decreasing over time. I don't really know where the flicker floor is on a Thunderbolt-class clock versus where it will be on a local cesium standard. The sigma-tau statistics for the more common HP 5061-era clocks were never really specified for periods more than a day, while at the same time, there don't seem to have been many long-term tests run on Thunderbolts and other GPS clocks to see where their performance flattens out. It would be good to see some more long-term trials. Said, do you have data for the long-term (multi-week) floors of the various Jackson Labs GPSDOs? Intuitively, I don't believe a GPSDO can outperform an HP 5071A-era clock over periods greater than a few hours. But it may be reasonable to benchmark 5061A-class standards with a good GPSDO setup. We really need some more data from trials lasting multiple weeks. -- john ___ 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] Measuring ADEV using TBolt-Tic tester
On 07/10/11 20:59, Azelio Boriani wrote: I know that few of the GPS constellation satellites carry a Cs clock instead of the Rb one: is it possible to take advantage from this? I think not because Cs and Rb satellites are equally well steered but using the masking options of GPS receivers maybe that Cs clocks can help. Many GPS sats has both Cs and Rb clocks, and then others have only Rb clocks. Which clock is being in use you need to check. Recall that the clocks in the birds is really just transfer oscillators which is corrected for by user data parameters. Also, there are other source of errors to add such as errors in orbital parameters, etc. So, you could select which birds you tune into, but restricting which birds in view you use will reduce your ability to RAIM out false tickers when you need to or average out multipath issues of particular birds. Also, the noise of the receiver won't change. So, for this purpose I think it is not helpful. 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] Measuring ADEV using TBolt-Tic tester
John What was the RMS and PP phase noise for your 8e-14 test? Something to keep in mind is that although the Z3801 has a better Osc than the typical Tbolt. Long term, really low noise is all about the quality of the GPS signal and engine. The Z3801's GPS engine is far inferior and not even close to the 10 to 100 ps, 1 sec noise that a Tbolt engine has. So how much does that effect the mid term GPS Phase noise which is highly dominated by how good of antenna system one has. Sounds like comparison is needed. ws * Some test like these are on my list for this winter. I am planning to look at a Z3801A versus a couple of 5061 class units: one with a high stability tube that I think is in very good condition, and another with an FTS replacement tube of probably typical surplus quality. I can also add a TBolt into the mix. I'm hoping to lash up multiple 5334 counters in TIC mode so I can do several comparisons simultaneously. In an early test of the 004 tube vs. Z3801A over a week or so, I saw what looked like a floor in the 8e14 range. John ___ 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] the care and feeding of LPRO's
They are APC double conversion(online) UPSs. I ended up buying them because my washing machine makes the lights in the basement flicker when it runs so I didn't want that feeding through into my equipment. I've looked into the ferroresonant regulators like the Sola MCR series but they are pretty expensive. On Fri, Oct 7, 2011 at 12:14 PM, Jim Lux jim...@earthlink.net wrote: On 10/7/11 11:16 AM, Eric Garner wrote: fortunately, everything in the lab(basement) is on UPSs so in theory the input voltages to the equipment should be pretty constant and I was already planning on using a linear supply. What kind of UPS? A static inverter? Most UPSes just feed the line through until it goes out of range, and then it switches (within 8-10 ms) to the output of the inverter. And even when on inverter, the output voltage regulation isn't all that hot, unless you've got a special inverter. A 5-10% variation in voltage from an inverter/UPS wouldn't be surprising.. (why should they try to do better.. the goal is to keep the equipment on, not serve as a voltage regulator) ___ 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. -- --Eric _ Eric Garner ___ 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] the care and feeding of LPRO's
I'm using Opti-UPS, but the same idea. They have software such that you can monitor the power being delivered, frequency, voltage, etc. The only real drawback to double conversion is the fan noise. The Opti-UPS is slightly quieter than the APC, but not by much. The fan noise is quite annoying. You also have the converter efficiency loss. These double conversion units don't have to react, because they are already online. You can hear the relay click when it detects a line disturbance. ___ 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] Measuring ADEV using TBolt-Tic tester
Long term, really low noise is all about the quality of the GPS signal and engine. And the antenna, and the multi-path, and ionosphere, etc. ... With a Z3801A or TBolt (or any cheap single channel GPS) receiver you should expect maybe a 5 to 10 to 15 ns variation over a 12 or 24 hour period. You should be able to see this with a 5065A or a good Cs reference. The Z3801's GPS engine is far inferior and not even close to the 10 to 100 ps, 1 sec noise that a Tbolt engine has. Careful, each does averaging. So to compare you have to include the time constant into the equation. The RS232 numbers the TBolt reports are heavily averaged so at 1 second they always look a lot better than they actually are. If you have hard data for your claim, I'd be interested in seeing it. /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] Looking for a Counter
On 10/7/2011 8:26 AM, shali...@gmail.com wrote: I bought two HP 5334B on ebay for under $100 each (that was a couple of years ago). Nice counter, with GPIB. Didier KO4BB And no fans in the 5334, so quiet. ___ 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] Measuring ADEV using TBolt-Tic tester
In that test I was just capturing the ADEV table from the TSC-5120 so don't have raw phase data. I'm curious where you got the noise data for the TBolt gps engine -- that's far better than I've seen quoted before. The Trimble data sheet that I found specs the system PPS accuracy at 20 nanoseconds one sigma; they don't separately spec the GPS engine. (The data sheet for the current Thunderbolt E data sheet says 15 nanoseconds.) The USNO says that their filtered, linear fit time transfer measurements over a two day period, over the entire constellation, have an RMS residual of 4 to 10 nanoseconds without SA (http://tycho.usno.navy.mil/gpstt.html). That may not be apples-to-apples methodology, but it implies that sub-nanosecond results may be difficult to obtain. John On Oct 7, 2011, at 4:16 PM, ws at Yahoo warrensjmail-...@yahoo.com wrote: John What was the RMS and PP phase noise for your 8e-14 test? Something to keep in mind is that although the Z3801 has a better Osc than the typical Tbolt. Long term, really low noise is all about the quality of the GPS signal and engine. The Z3801's GPS engine is far inferior and not even close to the 10 to 100 ps, 1 sec noise that a Tbolt engine has. So how much does that effect the mid term GPS Phase noise which is highly dominated by how good of antenna system one has. Sounds like comparison is needed. ws * Some test like these are on my list for this winter. I am planning to look at a Z3801A versus a couple of 5061 class units: one with a high stability tube that I think is in very good condition, and another with an FTS replacement tube of probably typical surplus quality. I can also add a TBolt into the mix. I'm hoping to lash up multiple 5334 counters in TIC mode so I can do several comparisons simultaneously. In an early test of the 004 tube vs. Z3801A over a week or so, I saw what looked like a floor in the 8e14 range. John ___ 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] Measuring ADEV using TBolt-Tic tester
Hi Tom and Warren, With a Z3801A or TBolt (or any cheap single channel GPS) receiver you should expect maybe a 5 to 10 to 15 ns variation over a 12 or 24 hour period. You should be able to see this with a 5065A or a good Cs reference. Hope to get a working 5065A in a month or two... ;-) The Z3801's GPS engine is far inferior and not even close to the 10 to 100 ps, 1 sec noise that a Tbolt engine has. Careful, each does averaging. So to compare you have to include the time constant into the equation. The RS232 numbers the TBolt reports are heavily averaged so at 1 second they always look a lot better than they actually are. If you have hard data for your claim, I'd be interested in seeing it. Where comes the averaging on the Tbolt messages? Looking at these (old) plots of two Tbolts running on the same antenna a few years ago. (I have not searched for the orginal datalogs.) http://www.lysator.liu.se/~bg/timenuts/sd_doppler.png http://www.lysator.liu.se/~bg/timenuts/csum_sd_doppler.png Eying the single difference plot, having around 1cm/s rms noise, that translates to 1/30 ns/s or 33ps 1 second noise. Does that look ok with you? Warren: A really good Tbolt set up will hold around 2 ns of phase noise. Where are you getting phase measurements out of the Tbolt? Are you converting doppler measurements to phase? Or is your phase refereing to something else? kind regards, 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] Measuring ADEV using TBolt-Tic tester
The noise data is my measured values which I do several different ways. Some of which are: The GPS engine value was calculated from measuring the UNFILTERED RMS noise of the freq plot data using LadyHeather, backed up by the independent way of looking at the UNFILTERED 1 sec ADEV values obtained when plotting the ADEV from that data using an external low noise osc. The other proof that the data is unfiltered was done by black box testing of small near instantaneous freq changes of 1e-10 and measuring and how long it took the Tbolt plot to settle to the new freq value using different filter setting. The answer is that it knows the correct freq (within it's nose limits) in the next 1 sec sample period when the filter is turned off. As for the ns phase noise that is the RMS Phase noise value from LH using a good LPRO osc with it's Time constant set to many hrs. (Phase correction TC was 100K sec). The RMS noise value is very insensitive to the filter setting up to 1000 seconds because most of the phase noise is slower than 1000 seconds. As far as the 4 to 10 ns day to day USNO data , that has nothing to do with sub ns short term noise which I generally limit to more like a few minutes of sampel time, and if there is a satellite change during the test run, then I start the test over because I'm looking at GPS engine noise and not the GPS noise causes by changing satellites etc. As far as the 4 to 10 ns over a two day period, that agrees pretty well with what I see some times on a bad day. On a good day I can get more like 2 to 3 ns, with a 500 sec filter, on a bad day up to 5 or 6 ns. For some periods lasting up to 5 to 6 hrs, I've seen numbers as low as 1.5 ns RMS. ws ** ) r - Original Message - From: John Ackermann N8UR In that test I was just capturing the ADEV table from the TSC-5120 so don't have raw phase data. I'm curious where you got the noise data for the TBolt gps engine -- that's far better than I've seen quoted before. The Trimble data sheet that I found specs the system PPS accuracy at 20 nanoseconds one sigma; they don't separately spec the GPS engine. (The data sheet for the current Thunderbolt E data sheet says 15 nanoseconds.) The USNO says that their filtered, linear fit time transfer measurements over a two day period, over the entire constellation, have an RMS residual of 4 to 10 nanoseconds without SA (http://tycho.usno.navy.mil/gpstt.html). That may not be apples-to-apples methodology, but it implies that sub-nanosecond results may be difficult to obtain. John On Oct 7, 2011, at 4:16 PM, ws at Yahoo warrensjmail-...@yahoo.com wrote: John What was the RMS and PP phase noise for your 8e-14 test? Something to keep in mind is that although the Z3801 has a better Osc than the typical Tbolt. Long term, really low noise is all about the quality of the GPS signal and engine. The Z3801's GPS engine is far inferior and not even close to the 10 to 100 ps, 1 sec noise that a Tbolt engine has. So how much does that effect the mid term GPS Phase noise which is highly dominated by how good of antenna system one has. Sounds like comparison is needed. ws * Some test like these are on my list for this winter. I am planning to look at a Z3801A versus a couple of 5061 class units: one with a high stability tube that I think is in very good condition, and another with an FTS replacement tube of probably typical surplus quality. I can also add a TBolt into the mix. I'm hoping to lash up multiple 5334 counters in TIC mode so I can do several comparisons simultaneously. In an early test of the 004 tube vs. Z3801A over a week or so, I saw what looked like a floor in the 8e14 range. John ___ 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] Measuring ADEV using TBolt-Tic tester
ws) responses below *** From: Tom Van Baak t...@leapsecond.com Long term, really low noise is all about the quality of the GPS signal and engine. And the antenna, and the multi-path, and ionosphere, etc. ... ws) And all the other things that go into making a Good GPS signal setup With a Z3801A or TBolt (or any cheap single channel GPS) receiver you should expect maybe a 5 to 10 to 15 ns variation over a 12 or 24 hour period. You should be able to see this with a 5065A or a good Cs reference. ws) Are your Phase numbers RMS, Peak, or Peak to peak? ws) On a good day 1/2 day my Tbolt's phase can be below 10 ns PP, on a not so good couple of days it can be 5 to 10 ns RMS The Z3801's GPS engine is far inferior and not even close to the 10 to 100 ps, 1 sec noise that a Tbolt engine has. Careful, each does averaging. So to compare you have to include the time constant into the equation. The RS232 numbers the TBolt reports are heavily averaged so at 1 second they always look a lot better than they actually are. If you have hard data for your claim, I'd be interested in seeing it. ws) My statements are when using raw 1 sec data without any averaging. For the Tbolt, a test anyone can do is turn off LH filter and measure the ppt RMS freq offset value over a short time period. For the Z3801, I think you have to take the difference between each two phase output values to be able to see freq changes in 1 sec. ws) To validate the data, just need to cause the Osc to make a small known freq step in under 1 second and see what happens. See how big of freq step is needed to be able to see a freq change above the noise and measure how long it takes for the new average freq value to settle. Do the above with several different filter settings such as 0, 10, and 100 seconds The freq step can be done with a voltage step on the osc's EFC (using the manual DAC setting) or by tilting the osc and letting G do the freq offsetting. ws) Tbolt answers I got are: 5e-11 Peak freq change is visible and valid in the next 1 sec output with LH's filter set to zero 2 e-11 peak freq change setting is visible and settled within 10 seconds with LH filter set to 10 seconds 5e-12 freq change is measurable within 100 seconds with LH Filter set to 100 seconds. ws) I've never measured a Z3801 but I have measure an oncore GPS engine which I think is what is used in them. It had a couple decades worse resolution for the one second test ws) Before picking at the fine details and getting totally off the subject which is how to use the Tbolt to make valid ADEV measurements. How about someone verifying the method by comparing the ADEV noise readings using an external Osc that is known quieter than the Tbolt's Nose floor (such as a low noise 10811) and one that is nosier than the Tbolt's freq noise floor (like a LPRO). For a plot of the Tbolt's noise floor I got see: http://www.febo.com/pipermail/time-nuts/attachments/20111007/48d1ab68/attachment-0001.gif An important first step, and one simple way to verify that the Tbolt's total GPS antenna system is ALL setup and working well, is to check that the Tbolt's phase noise is well under 3 ns RMS as reported by LH, over a one or two day time span with the TC set to 1000 sec and Damping set to 0.7 and with the display Filter off. Also a good idea to check that the ppt RMS freq noise is around 3e-12 with a filter setting of 100 sec and 1.5e-11 with filter off with the above conditions. ws /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.
[time-nuts] Measuring short term stability minus linear drift
I want to measure the short term stability of a source with substantial linear drift. I would like some measure of stability along the lines of Allan deviation, but I only want to measure the noise and ignore the drift. AFAIK, ADEV treats linear drift like a form of noise. Has this problem been solved before? Any ideas? Rick Karlquist ___ 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] Measuring short term stability minus linear drift
-Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts- boun...@febo.com] On Behalf Of Rick Karlquist Sent: Friday, October 07, 2011 9:32 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] Measuring short term stability minus linear drift I want to measure the short term stability of a source with substantial linear drift. I would like some measure of stability along the lines of Allan deviation, but I only want to measure the noise and ignore the drift. AFAIK, ADEV treats linear drift like a form of noise. Has this problem been solved before? Any ideas? Use TimeLab, Plotter, Stable32, or any other graphing application that supports Hadamard deviation. Any of these apps will also let you subtract the linear or quadratic trend from the data itself... but if all you want to do is view ADEV without the effects of drift, HDEV will do that. -- john ___ 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] Measuring short term stability minus linear drift
I want to measure the short term stability of a source with substantial linear drift. I would like some measure of stability along the lines of Allan deviation, but I only want to measure the noise and ignore the drift. AFAIK, ADEV treats linear drift like a form of noise. Has this problem been solved before? Any ideas? Rick Karlquist Right, ADEV will suffer with linear drift. Plot the frequency first to see how linear the drift is. If it looks like you expect (that is, mostly a straight line) then it's safe to remove it from the raw data with a quadratic least squares fit. Then compute ADEV on the residuals. Another way it to use HDEV on the raw data. Let me know if you want the command line tools I use for all this. The other suggestion is to use John Miles' TimeLab. /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.
