[time-nuts] Any spare HP 5065A A3 and HP5062C A10 modules?
Hi, Doing some experiments and need HP 5065A A3 and/or HP5062C A10 modules. They are the 5 to 60 MHz and 5 to 90 MHz multiplier modules. Anyone have some laying around? Cheers, Corby Dawson ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Quality of timing mode GPS vs survey accuracy
Be aware the some receivers report altitude in MSL (mean sea level) and others use AGL (height above ground level). Depending upon where you are and the conversion model, there can be over 100 meters difference. --- I >if I take a survey > with several GPS receivers will they all get the same answer? ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Quality of timing mode GPS vs survey accuracy
On 5/8/20 3:38 PM, Charles Steinmetz wrote: Jim wrote: I'm attaching a screen shot of 4 receivers, taken at the same time (within seconds,not time-nuts same time) All sitting on the table together. One might expect closer agreement if all of the receivers were fed from one antenna through a splitter, but even then each rx will choose its own series of constellations and will switch constellations at different times. There will also be phase dispersion among the rx input filters. And lots of other small effects. one might so expect. But I'm not too sure. There's >10 meters difference in the positions (in the X coordinate of the ECEF position alone). They're all tracking the same satellites (except b203) but the S/N is noticeably different among them. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] advice sought on basic gpsdo
While I'm no expert at time, or Arduino yet, the first thing I would look at is getting the bootloader to run with not 16MHz, but a 10MHz clock. Not having looked at it I don't know if it requires modifying and re-flashing, but it might. Now the VCTCXO can clock the Arduino and the Arduino IDE would work unmodified. Code the Arduino chip to lock the VCTXCO to GPS 1PPM, and you can accurately keep time of day in RAM. As long as you have a valid battery backup 5V supply just detect the loss of 1PPM (or GPS signal) and freeze the VCTXCO control voltage. With some effort the clock can auto-set itself from the GPS when the GPS is in a good state. Not simple coding, but doable. Bob L. > Sent: Friday, May 08, 2020 at 7:06 PM > From: "Robert Melville" > To: time-nuts@lists.febo.com > Subject: [time-nuts] advice sought on basic gpsdo > > Fellow time nutters: > > Any input or advice on the following project would be appreciated. > > I want to make a small, portable, batter-operated clock that will > spend most of its time docked into a charging bay with access > to a signal from a GPS receiver -- either 1 PPs or 10. MHz. > The device will have a voltage-controlled TXCO that will be disciplined > by the GPS input unless the unit is traveling. > > I have seen several designs for disciplined oscillators using a uP, > such as an Arduino or a PIC. The main decision seems to be between > 1 PPs or 10 MHz as the input. 1 PPs might be preferable because > not all cheap GPS receivers seem to provide 10.00 MHz out. > Mostly, I want accurate time but a frequency reference with > decent phase noise would be useful. > > 1. I am tending towards a published design from Lars Walenius, in part > because > it uses a familiar uP (an Arduino) but am open to other designs. > > 2. What advice to people have on glitch-free switching when > docking/undocking the unit from the GPS??? > This seems to be something like the de-bouncing problem for a > push-button. > > 3. Has anyone used the Arduino time library withOUT the Dallas RTC chip -- > i.e., some other source of time such as the from the locked oscillator? > > 4. Can anyone share experience with conditioning the power going into the > TXCO -- to what extent can digital noise from the uP or counters > contaminate the phase noise of the TCXO? Does a separate isolating buffer > help for the "osc out" port? I have had good success in the past with > so-called "active bypassing" to deliver very clean power to an oscillator. > > Thanks to all for your attention to this message -- I am glad to look at any > and all possible designs. > Happy time-keeping! > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] advice sought on basic gpsdo
Fellow time nutters: Any input or advice on the following project would be appreciated. I want to make a small, portable, batter-operated clock that will spend most of its time docked into a charging bay with access to a signal from a GPS receiver -- either 1 PPs or 10. MHz. The device will have a voltage-controlled TXCO that will be disciplined by the GPS input unless the unit is traveling. I have seen several designs for disciplined oscillators using a uP, such as an Arduino or a PIC. The main decision seems to be between 1 PPs or 10 MHz as the input. 1 PPs might be preferable because not all cheap GPS receivers seem to provide 10.00 MHz out. Mostly, I want accurate time but a frequency reference with decent phase noise would be useful. 1. I am tending towards a published design from Lars Walenius, in part because it uses a familiar uP (an Arduino) but am open to other designs. 2. What advice to people have on glitch-free switching when docking/undocking the unit from the GPS??? This seems to be something like the de-bouncing problem for a push-button. 3. Has anyone used the Arduino time library withOUT the Dallas RTC chip -- i.e., some other source of time such as the from the locked oscillator? 4. Can anyone share experience with conditioning the power going into the TXCO -- to what extent can digital noise from the uP or counters contaminate the phase noise of the TCXO? Does a separate isolating buffer help for the "osc out" port? I have had good success in the past with so-called "active bypassing" to deliver very clean power to an oscillator. Thanks to all for your attention to this message -- I am glad to look at any and all possible designs. Happy time-keeping! ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Quality of timing mode GPS vs survey accuracy
Jim wrote: I'm attaching a screen shot of 4 receivers, taken at the same time (within seconds,not time-nuts same time) All sitting on the table together. One might expect closer agreement if all of the receivers were fed from one antenna through a splitter, but even then each rx will choose its own series of constellations and will switch constellations at different times. There will also be phase dispersion among the rx input filters. And lots of other small effects. Best regards, Charles ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Quality of timing mode GPS vs survey accuracy
Hi > On May 8, 2020, at 5:12 PM, Hal Murray wrote: > > > Is there any published data on what happens to the quality of time if the > survey is off by xxx meters? Speed of light plus distance off “correct” plus constellation geometry are what are usually tossed into examples. Turning that into an exact error number for this receiver design at time = x …. never seen it taken that far. You could do it yourself for a hypothetical processing approach. > > Do all the GPS receivers use the same coordinate system? GPS uses a coordinate system, receivers translate this into another system to display the results. Many can be set to a variety of coordinate systems. Unless there are bug in the firmware, when set to the same system they should be talking the same way. Mr Google will give you a long list of hits going into this for each GNSS system. > If I take a survey > with several GPS receivers will they all get the same answer? Nope. If you take a survey with the *same* receiver, there will be some level of “this pass does not agree with that pass”. How big the errors are depends a lot on: 1) what sort of receiver you have (single band / multi band / design era / make / model) 2) what sort of antenna you have (fancy geodetic / simple pole mount / mag mount …) 3) how well you have things set up (sky view ….) 4) how bad your local situation is ( multi-path, jammers, RFI / EMI ….) 5) how long the survey is ( minutes / hours / days / weeks / month ….) 6) what the conditions are (space weather / local weather / GNSS system issues …) 7 )what sort of post processing you do ( antenna corrections …. IGS data sets used ….) (and on and on and on ….) For timing, you may not care about errors dimensioned in mm, but there are people who do. Yes, this is a basic issue with wide open questions :) Bob > > > -- > These are my opinions. I hate spam. > > > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Quality of timing mode GPS vs survey accuracy
In message <20200508211209.315c1406...@ip-64-139-1-69.sjc.megapath.net>, Hal Mu rray writes: >Is there any published data on what happens to the quality of time if the >survey is off by xxx meters? I played with that many years ago, using the reported residuals from the OnCore to slowly sneak in on the position which averaged the residuals out. Made no measurable (for me) difference on the timing. http://phk.freebsd.dk/raga/sneak/ -- 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@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Quality of timing mode GPS vs survey accuracy
Is there any published data on what happens to the quality of time if the survey is off by xxx meters? Do all the GPS receivers use the same coordinate system? If I take a survey with several GPS receivers will they all get the same answer? -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Modern HP5065A adjustment ideas
In message , cdel...@juno.com writes: >Also if you run an AD plot and you meet or exceed specs the SN is OK. > >I have seen some units with a SN of 6000! Ohh... I tried measuring SN with my HP3577 and got around 2500, so I thought I was doing something bogus... One other question: Have I understood it right that the control voltage for +/-50 on the fine frequency pot should be +/- 1V for 10544 but only +/- 0.5V for the 10811 ? -- 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@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Modern HP5065A adjustment ideas
Poul-Henning, Hi! I never use the XY method in the manual. It's much easier just to use the scope in the normal mode. I don't try to synch the scope, just use the fine horizontal control to give me a few cycles on the trace with it close to stationary (slow roll). The splitting is easy to adjust out. One trick if you run out of range on the phase pot: Insert a 137Hz signal thru a 10Meg resistor (see test cable described in the manual) into A7. Monitor the input pin to the phase detector and manually adjust the signal generator for a peak amplitude. This measures where the A7 bandpass filter is centered. Now adjust the A8 modulation frequency to match the measured frequency. This sometimes makes it much easier to adjust the phase. I very seldom measure the SN since it's met if you have >500mV at A7TP2. Also if you run an AD plot and you meet or exceed specs the SN is OK. I have seen some units with a SN of 6000! Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
