Re: [time-nuts] Tektronix Sample Heads
Bill, As I recall it, it has a 400 kS/s rate. Undersampling as it is, if properly used, it is a marvelous tool. The TDR capability had such a live component to it that I miss in newer (but butter calibrated) systems. No wonder I have a system myself these days. The one thing I would love to have, is to be able to run the TDR/TDT post-processing software. I haven't seen any free alternative either. Cheers, Magnus On 04/26/2015 06:26 AM, Bill Byrom wrote: I still work for Tektronix, but not in Service or the sampling scope product line. I'm a Tektronix field RF Application Engineer. You can find the service manual for the SD-24 at: http://www.tek.com/oscilloscope/sd24-manual/sd-24-service-manual But it's not user repairable, so there are no schematics (just block diagrams). The SD-24 was introduced about 25 years ago for the 11801/11802 family of sampling scopes. The SD-24 is a dual TDR sampling head, so it can generate a fast risetime step from either or both outputs. The steps can be the same polarity (for common mode testing) or opposite polarity (for differential mode testing). The sampling bridges measure both the incident (forward) and reflected pulses. The SD-26 is basically the same product without the TDR pulse sources. The SD-22 is a lower noise (and lower bandwidth) version of the SD-26. As pointed out by others, these heads aren't useful without a 11800 or CSA800 family mainframe. The SD-series measure signals using sequential equivalent-time sampling. * Single events can't be measured. Only repeating signals with a low-jitter trigger source can be measured. The trigger must be an externally input signal (unless you use the SD-24 with the internal TDR step source or an external signal pickoff transformer). * Each trigger edge which is accepted by the mainframe is delayed by a precise amount and then used to create a sampling strobe which is sent by the mainframe to the sampling head. * The sampling head (SD-24/26/22) actually measures the error difference between an internal feedback loop and the sampled input voltage. Since the sampling bridge has a high loss, the error voltage is multiplied by the assumed bridge loss to create the new feedback loop voltage. A high resolution low-noise A/D converter measures the loop voltage for the microprocessor-created raster scan display on the CRT. * The sampling system takes around 10 microseconds to reset between triggers. So no more than about 100K triggers and samples can be made per second. It might be a little slower than this - I'm remembering this from my experience over 20 years ago. * The delay from the trigger input to the sampling strobe (sent to the SD-xx sampling head) is sequentially delayed by slightly increasing time delays to create a time domain display. The delay increment between samples can be less than 1 ps (down in the 100 fs range). * Since the signal is not actually sampled in real time, this is called equivalent-time sampling. In this case, the sampling strobe is sequentially advanced in time upon trigger signal acceptance. This results in very high time accuracy with low jitter (a couple of ps RMS jitter in these older products). * The voltage measurement range is usually a few hundred millivolts peak-peak, while the damage level is at around 3 volts. -- Bill Byrom N5BB On Fri, Apr 24, 2015, at 10:42 PM, Ivan Cousins wrote: Since I was working at Tektronix at the time, I still remember the first instruments that were in the family. Like the main frames 11801, 11802, CSA801, CSA802, CSA803, etc and sampling heads SD-20, SD-22, SD-24, etc. You can try a google search like Tektronix 11801 filetype:pdf. You can also try a google search like Tektronix SD-24 filetype:pdf. If you want to know more about google filetypes, enter google filetype search into a google search. To find out more about sampling heads you can look for information on the instruments they connect to. w140.com has a lot of information on both the mainframes and the sampling heads. http://w140.com/tekwiki/wiki/Main_Page#11000_Series http://w140.com/tekwiki/wiki/SD-24 It is good to know more google-fu. It is even better to be able to still remember about any of this. :) Ivan Cousins _ 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] Corrected HP 10544A schematic
That reminds me -- years ago I cleaned up, corrected, and annotated a copy of the HP 10544 schematic. I dug it up and just posted it to Didier's site (http://www.ko4bb.com/manuals/). When it comes off quarantine, you can find it by searching for: HP 10544A schematic corrected and annotated (do not type the quotation marks). Didier wrote: The quarantine is officially over (for this week :) Luca wrote: Thank you very much Didier for your wonderful site Yes, thank you for the terrific resource, Didier! thank you again Charles for your precious schematic. My pleasure. I hope people find it useful. 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] DDS, OCXO and ADEV
The counter is in TIME MODE. And simple calculation could transform it to frequency as necessary. For example: 1/(350.50824*10^-9) 2852999.97512184021693755330 OR 1/0.00350508240900 2852999.96779619226350692058 Which is pretty close to my DDS VFO freq. value [2853000] I switch counter to TIME MODE, because ADEV1 utility using times, not frequency: Here is from documentation: Adev1 works on everything from pendulum clocks to hydrogen masers. The only restrictions are that the data must be phase (time interval) rather than frequency; the data must be sequential (no gaps); and the data should be free from glitches or outliers. I am using 10 second intervals for the measurement. DDS VFO clocked by Trimble TB and its using AD9852 chip. Regards, V.P. On 2015-05-03 10:01, Bob Camp wrote: Hi Either the output data is with the counter set to time mode (and it’s in 100’s of ns) or you have it set to frequency mode and have a very stable system. Bob On May 2, 2015, at 9:53 PM, d0ct0r t...@patoka.org wrote: Hello, I would like to create some charts for ADEV for following setup: HP5386A counter connected to External REF. (OCXO). The input of counter connected to my DDS VFO. The frequency on VFO is 2853000 Hz. Here is what I got from counter via GPIB: S +3.505082408E-7 S +3.505082408E-7 S +3.505082408E-7 S +3.505082408E-7 S +3.505082408E-7 S +3.505082408E-7 S +3.505082408E-7 S +3.505082409E-7 S +3.505082408E-7 S +3.505082409E-7 S +3.505082408E-7 S +3.505082408E-7 S +3.505082408E-7 I converted it to following form: 0.00350508240900 0.00350508240900 0.00350508240900 0.00350508240800 0.00350508240900 0.00350508240900 0.00350508240900 0.00350508240900 0.00350508240900 0.00350508240900 0.00350508240900 0.00350508240900 0.00350508240900 0.00350508240900 0.00350508240900 Then I tried to use ADEV by tvb (long life to Tom!). See attached file 1b.bmp And I tried to create the charts for the collected data. See attached file 1a.bmp. But it seems I am doing something wrong. Any advises will be greatly appreciated. Thanks ! -- WBW, V.P.1a.png1b.png___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- WBW, V.P. ___ 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] Important parameters for a GPS/GNSS antenna
In message B373DA32B0D748A9B45D90A7D38B2C32@pc52, Tom Van Baak writes: When you post-process raw GPS data you get to include antenna phase center / gain / az/el corrections for free. Speaking of which... I wonder if anybody ever made a rotating GPS antenna to average out the X-Y phase-center offset ? -- 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 10544A repair
The quarantine is officially over (for this week :) Thanks for the uploads Didier KO4BB PS: I am now trying to move the manuals and equipment specific docs out of the GPS Timing folder into the manufacturer's folders. I realize it may be less convenient for those who are only interested in timing information, but it makes the overall organization of the site easier for me and (I hope) for a majority of users. Until that is complete, you can find HP timing info in two folders, the GPS Timing folder and in the HP Agilent folder for instance. The search works through the entire site, so finding stuff should not be harder. As I am sure most of you have noticed, I have implemented a Content Management System. The main reason was to make the site easier to manage. A side benefit is to keep my Google rankings up since the CMS is mobile friendly and now Google ranks down the sites that are not. I am sorry for those who lament the loss of Comic Sans... The old site is still there, the old links still work but the old pages won't be maintained. After a while, they will go away. On April 27, 2015 4:14:07 AM CDT, Charles Steinmetz csteinm...@yandex.com wrote: That reminds me -- years ago I cleaned up, corrected, and annotated a copy of the HP 10544 schematic. I dug it up and just posted it to Didier's site (http://www.ko4bb.com/manuals/). When it comes off quarantine, you can find it by searching for HP 10544A schematic corrected and annotated. 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. -- Sent from my Motorola Droid Razr HD 4G LTE wireless tracker while I do other things. ___ 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] DDS, OCXO and ADEV
Hi Either the output data is with the counter set to time mode (and it’s in 100’s of ns) or you have it set to frequency mode and have a very stable system. Bob On May 2, 2015, at 9:53 PM, d0ct0r t...@patoka.org wrote: Hello, I would like to create some charts for ADEV for following setup: HP5386A counter connected to External REF. (OCXO). The input of counter connected to my DDS VFO. The frequency on VFO is 2853000 Hz. Here is what I got from counter via GPIB: S +3.505082408E-7 S +3.505082408E-7 S +3.505082408E-7 S +3.505082408E-7 S +3.505082408E-7 S +3.505082408E-7 S +3.505082408E-7 S +3.505082409E-7 S +3.505082408E-7 S +3.505082409E-7 S +3.505082408E-7 S +3.505082408E-7 S +3.505082408E-7 I converted it to following form: 0.00350508240900 0.00350508240900 0.00350508240900 0.00350508240800 0.00350508240900 0.00350508240900 0.00350508240900 0.00350508240900 0.00350508240900 0.00350508240900 0.00350508240900 0.00350508240900 0.00350508240900 0.00350508240900 0.00350508240900 Then I tried to use ADEV by tvb (long life to Tom!). See attached file 1b.bmp And I tried to create the charts for the collected data. See attached file 1a.bmp. But it seems I am doing something wrong. Any advises will be greatly appreciated. Thanks ! -- WBW, V.P.1a.png1b.png___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ 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] Important parameters for a GPS/GNSS antenna
I wonder if anybody ever made a rotating GPS antenna to average out the X-Y phase-center offset ? PHK, I ran across this wonderful shaker table experiment and concluded that post-processing would always be better than playing moving antenna games. See pages 9-13 of: http://www.nceo.ac.uk/assets/presentations/2012_conference_NOTTINGHAM/NCEOCONF2012_0919_Atkins.pdf If nothing else, it makes a wonderful test of your GPS receiver's time/position resolution. Something to do with an old 33 RPM turntable... /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] DDS, OCXO and ADEV
Hi Vlad, Here are some comments. Please read carefully. Look at your data and notice that every reading is the same 3.505082408E-7, except one is 3.505082409E-7. That's not going to give you very good plots at all. Also you're not going to get much information out an ADEV tool with just 13 points. It's not clear from your post what those readings are. They do not look like phase difference. They do not look like frequency, or frequency offset, or fractional frequency error. Instead I will guess they are period, since 1 / 3.505082408E-7 is 2852999.968 and that is close to the frequency you mentioned: 2853000 Hz. My ADEV tools do not accept period or frequency data as input. This is by design. They expect a series of phase measurements. That is, a periodic sampling of the phase difference between the REF and the DUT. There is no need to convert a number like 3.505082408E-7 to a number like 0.00350508240900. Software knows how to read floating point numbers. You can convert your period measurements (seconds) to frequency (Hz) by inverting them. Some tools will then take this frequency data as input. You can convert period measurements (seconds) to fractional frequency error by inverting, subtracting 2853000 Hz, and dividing by 2853000 Hz. Some tools will take fractional frequency error as input. Or, you can convert your period measurements to phase difference by subtracting 1/2853000 and accumulating (running sum) the phase error for each sample. There's a tool for you that does this, p2t, and the arguments are the nominal phase and the sample rate ( www.leapsecond.com/tools/ ). In other words, you can get correct ADEV statistics from your gpib.dat file using: sed gpib.dat s/...// | p2t 1/2853000 10 | adev1 10 I won't get into zero dead time measurements yet. One step at a time. I'm not sure if my tools are the best for you. Command line tools work best when you understand what's going on and can keep track of units and such. Instead consider using John's TimeLab ( www.ke5fx.com/timelab/readme.htm ) which is a GUI with an extensive help system. Your DDS vs OCXO plot looks suspect. You must remove that huge outlier point before you do any statistical analysis (like ADEV). The y-axis of that plot doesn't look right: all the grid lines are zero. Also there are no units. The Allan Variance Plot Y you included is odd. I would not expect a y-axis scale to go from -31 to -45. But this is probably a side-effect of your feeding period readings into an ADEV tool instead of a phase difference time series. If you want send me the full raw data file (more than 13 points), I'll make a set of plots that you can compare against. /tvb - Original Message - From: d0ct0r t...@patoka.org To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, May 02, 2015 6:53 PM Subject: [time-nuts] DDS, OCXO and ADEV Hello, I would like to create some charts for ADEV for following setup: HP5386A counter connected to External REF. (OCXO). The input of counter connected to my DDS VFO. The frequency on VFO is 2853000 Hz. Here is what I got from counter via GPIB: S +3.505082408E-7 S +3.505082408E-7 S +3.505082408E-7 S +3.505082408E-7 S +3.505082408E-7 S +3.505082408E-7 S +3.505082408E-7 S +3.505082409E-7 S +3.505082408E-7 S +3.505082409E-7 S +3.505082408E-7 S +3.505082408E-7 S +3.505082408E-7 I converted it to following form: 0.00350508240900 0.00350508240900 0.00350508240900 0.00350508240800 0.00350508240900 0.00350508240900 0.00350508240900 0.00350508240900 0.00350508240900 0.00350508240900 0.00350508240900 0.00350508240900 0.00350508240900 0.00350508240900 0.00350508240900 Then I tried to use ADEV by tvb (long life to Tom!). See attached file 1b.bmp And I tried to create the charts for the collected data. See attached file 1a.bmp. But it seems I am doing something wrong. Any advises will be greatly appreciated. Thanks ! -- WBW, V.P. ___ 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] DDS, OCXO and ADEV
I switch counter to TIME MODE, because ADEV1 utility using times, not frequency: No. ADEV1 expects phase. Not time, not period, not frequency. Here is from documentation: Adev1 works on everything from pendulum clocks to hydrogen masers. The only restrictions are that the data must be phase (time interval) rather than frequency; the data must be sequential (no gaps); and the data should be free from glitches or outliers. Busted! It looks like you broke all three rules: your data was period (not phase), your data has deadtime (gaps), and your data has glitches! Anyway, here is a more complete explanation. The word phase is confusing because it is used differently in time frequency metrology than in other branches of science. The units are seconds (not degrees, not radians, not rotations, not angles). Think of phase as simply the difference between the time that two clocks display. If you call one clock the reference and assume it is the true time, then phase is simply the time error of the DUT clock. Think of a wall clock; maybe 2 seconds behind, or 15 seconds ahead. This is the phase. It tends to wander slowly and grow larger over time. If you were to write down the time error of your clock once a day for a month you'd have a nice set of phase numbers that you can feed to any tool that computes ADEV. Note also that phase is a cumulative measurement. That is, every successive data point reflects the net clock error since you started collecting data. Even if you lost 29 days of data in the middle, you'd still know how far off the clock had drifted in time between day 1 and day 30. If this all makes sense so far, I'll go on to explain how period or frequency measurements are related to this. /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] HP 10544A repair
Thank you very much Didier for your wonderful site and thank you again Charles for your precious schematic. Finally i'm able to understand something more! Ciao! Luca iw2lje Milano Italy Il domenica 3 maggio 2015, Didier Juges shali...@gmail.com ha scritto: The quarantine is officially over (for this week :) Thanks for the uploads Didier KO4BB PS: I am now trying to move the manuals and equipment specific docs out of the GPS Timing folder into the manufacturer's folders. I realize it may be less convenient for those who are only interested in timing information, but it makes the overall organization of the site easier for me and (I hope) for a majority of users. Until that is complete, you can find HP timing info in two folders, the GPS Timing folder and in the HP Agilent folder for instance. The search works through the entire site, so finding stuff should not be harder. As I am sure most of you have noticed, I have implemented a Content Management System. The main reason was to make the site easier to manage. A side benefit is to keep my Google rankings up since the CMS is mobile friendly and now Google ranks down the sites that are not. I am sorry for those who lament the loss of Comic Sans... The old site is still there, the old links still work but the old pages won't be maintained. After a while, they will go away. On April 27, 2015 4:14:07 AM CDT, Charles Steinmetz csteinm...@yandex.com javascript:; wrote: That reminds me -- years ago I cleaned up, corrected, and annotated a copy of the HP 10544 schematic. I dug it up and just posted it to Didier's site (http://www.ko4bb.com/manuals/). When it comes off quarantine, you can find it by searching for HP 10544A schematic corrected and annotated. Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com javascript:; To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Sent from my Motorola Droid Razr HD 4G LTE wireless tracker while I do other things. ___ time-nuts mailing list -- time-nuts@febo.com javascript:; 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.
