Re: [time-nuts] HP10811-60212-B Pinouts.
Hi Dan, I found a picture that looks like your OCXO on Brooke Clarke's website. Maybe he has a schematic or pinouts for the oscillator. http://www.prc68.com/I/Images/Z3805A07b.jpg Bob From: d...@irtelemetrics.com d...@irtelemetrics.com To: time-nuts@febo.com Sent: Friday, October 10, 2014 6:31 PM Subject: [time-nuts] HP10811-60212-B Pinouts. Hi All, I recently picked up an HP10811-60212-B oscillator. However I don't happen to have the pinouts for this device. There are two coax cables, and cables with 6 pin headers. One Coax is 10Mhz, the other is EFC. Of the two 6 pin headers, one only has 4 wires (cable labeled P3). Colors are, BLK, RED, BLK, YEL, GRN, BLU. The other has all six pins (cable labeled P21) Colors are: GRY, GRY, RED, RED I've found the schematics for some of the 60xxx parts on the usual manual sites listed here, but not this one. Does anyone have any pinout for this oscillator and possibly the schematic for this thing? Also, any idea what the coax connector model is (Maybe a source to buy a mate???). It's a small push on type connector. I can post a picture if necessary. Thanks! Dan ___ 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] GPS jump
gign...@gmail.com said: Is it actually possible to phase lock two oscillators together cross the distance from DC to Colorado Springs? (2400 kilometers or so). ? I think so - if your clocks are stable enough. There is probably a simple rule for PLL stability based on round-trip-time and bandwidth (and other factors). -- 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.
Re: [time-nuts] HP10811-60212-B Pinouts.
b...@evoria.net said: I found a picture that looks like your OCXO on Brooke Clarke's website. Maybe he has a schematic or pinouts for the oscillator. http://www.prc68.com/I/Images/Z3805A07b.jpg More info here: http://www.prc68.com/I/Z3805A.html The Z3805A is very similar to the Z3801A Brooke: typo in http://www.prc68.com/Alpha.shtml Down at the bottom, the link to the Z3805A page goes to file:///C:/Webdocs_Hosted/I/Z3805A.html -- 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.
Re: [time-nuts] GPS jump
On 2014-10-11 00:49, Hal Murray wrote: gign...@gmail.com said: Is it actually possible to phase lock two oscillators together cross the distance from DC to Colorado Springs? (2400 kilometers or so). ? I think so - if your clocks are stable enough. There is probably a simple rule for PLL stability based on round-trip-time and bandwidth (and other factors). TWSTFT http://www.usno.navy.mil/USNO/time/twstt and http://tf.nist.gov/time/twoway.htm where NIST says stability is .1-1ns/day and better than GPS common view at 1-10ns accuracy http://tf.nist.gov/time/commonviewgps.htm -- Take care. Thanks, Brian Inglis ___ 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] FE-5680 Linux command line tool
Most EEPROMs have I2C or SPI interfaces. Some Flash chips have JTAG. Didier KO4BB On October 10, 2014 4:47:19 PM CDT, Tom Wimmenhove tom.wimmenh...@gmail.com wrote: Thanks Joe! I don't have the clip-ons but of course I could get them. I know the chip has a JTAG interface, but I've only used JTAG with chips that came with a programmer and software :) (except with OpenOCD over parport once, but that was in the stone age). Another question about the EEPROM dump Elio Corbolante. The chip has a 256Kbit (32KB) EEPROM and the dump is 160K: -rw-rw-r-- 1 tom tom 160K nov 8 2012 FE5680A_EEPROM.bin Which part in this dump is the actual data from the EEPROM? Thanks in advance. Regards, Tom On Fri, Oct 10, 2014 at 12:21 PM, Joseph Gray jg...@zianet.com wrote: I don't know how crowded the board is, but I would use an SMD DIP clip instead of unsoldering the chip. Joe Gray W5JG On Oct 10, 2014 8:30 AM, Tom Wimmenhove tom.wimmenh...@gmail.com wrote: I recently came across a thread on this list about undocumented FE5680 commands. I have been using a little linux command line tool I wrote years ago for tuning the unit and decided to add these commands to it. Since this mailing list was the place I found the unit (someone linked to an ebay seller) I figured I' d join the list and throw it on here :) http://www.tomwimmenhove.com/otherstuff/fe5680-0.2.tgz Now, the bad news. I had my unit running overnight while logging the serial command output that reads the ADC, and in the morning it was no longer locked. The 10MHz signal disappears about 5 seconds after power-on, and programmed offset was somehow reset to zero (it had been set to -645). So it appears as if the internal EEPROM has been corrupted. I read a post from Elio Corbolante where he posted EEPROM and firmware dumps. Anyone have any idea on how to re-write this firmware back into the EEPROM by hand (would this be possible through JTAG, or do I actually have to solder the chip out of there? :) ) Or maybe there's someone willing to sell their broken unit I could take the chip out of? Regards, Tom ___ 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. -- 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] Sun Outage
Just to put that in perspective, we're measuring a few degrees of phase shift in a 32 GHz signal on a path that is over a billion km long. Now this is fully qualified nuttiness :) Didier KO4BB On October 10, 2014 8:17:13 AM CDT, Jim Lux jim...@earthlink.net wrote: On 10/9/14, 10:16 PM, Andy wrote: Bob Stewart b...@evoria.net wrote: It occurred to me that one could use satellite signals as a meteorological instrument to measure the water density in the atmosphere above you. I wonder if the NWS does that. WHy yes they do: that's what weather radar is. It detects the reflections from the rain drops or ice crystals in the storms. These days, it's doppler radar, so not only do you get the density of the return but whether it is moving towards or away from the radar. If multiple radars in different places cover the same volume, you can get full X-Y motion. On a more time-nutty note, they also use the small variations in GPS signal propagation to do this kind of measurement. COSMIC (and soon to be launched COSMIC-2) measure GPS signals passing through the atmosphere from satellite to satellite- grazing the earth's surface, and by measuring the phase and amplitude variations (because you know the underlying GPS signal is locked to an atomic standard), you can infer the properties of the atmosphere at various elevations. Such radio occultation measurements are the 3rd or 4th most useful measurement in feeding the numerical models that are used for weather prediction. On an even more gnat's eyelash time measurement note: We use radiometers (basically a sensitive power meter) to measure water vapor content (and, incidentally, cloud cover) at the DSN stations, to remove some of the variation in the measurements of propagation delay to and from spacecraft. By carefully gnawing away at all sources of error, we can measure the round trip light time with accuracies of 1E-14 (1000 second tau), which is how we can measure range to something at Saturn to a few cm, and radial velocity (range rate) to a few mm/sec. Just to put that in perspective, we're measuring a few degrees of phase shift in a 32 GHz signal on a path that is over a billion km long. http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/18497/1/99-1986.pdf, page 7, shows some radiometer data from a 13.402 GHz radiometer I built installed in Las Cruces, NM. It was easy to tell when it was overcast or clear: clear is cold, because you're seeing sky; overcast is warm, because you're seeing the reflection of the ground, and the warm water in the clouds. ___ 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] GPS jump
http://users.on.net/~cdadsl/ Is a web page with all our different sites on it. Hobart 26m seems to be the only exception but I did make an adjustment on that day. But the adjustment didn't appear. All sites are collected and analysed separately with their own GPS clock. Some are old TACs and most are CNS mark II. It could be a fluke, but it does seem weird. And as was pointed out - this happened last year at around the same time. Well spotted Mike Cook! On 11 October 2014 09:54, Tom Van Baak t...@leapsecond.com wrote: Hi Jim, Can you tell me more about your configuration? What GPS receiver / antenna system do you use; L1 or L1/L2? Is this live 1PPS data, or post-processed from RINEX, etc. Is the data analysis done separately in 5 locations or is the raw data collected and processed together. Through IGS and NASA and BIPM there's GPS and maser data from all over the world so it should be possible to track this down. I can ask people I know too. But can you clarify how much the downward turn is? Is that ps/day, or ns/day, or what. Thanks, /tvb - Original Message - From: Jim Palfreyman jim77...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Thursday, October 09, 2014 4:43 PM Subject: [time-nuts] GPS jump Folks, We look after 5 separate hydrogen masers spread all over Australia and we collect tic phases between the masers and the GPS. On around ~Oct 7 we have noticed that the normal steady straight line (with standard daily noise) took a noticeable downward turn - on all 5 masers. Did anyone else who tracks H-masers notice this as well? Is it JPL making corrections? Jim Palfreyman ___ 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] GPS jump
Hi On Oct 10, 2014, at 11:20 PM, Brian Inglis brian.ing...@systematicsw.ab.ca wrote: On Oct 9, 2014, at 7:43 PM, Jim Palfreyman jim77...@gmail.com wrote: We look after 5 separate hydrogen masers spread all over Australia and we collect tic phases between the masers and the GPS. On around ~Oct 7 we have noticed that the normal steady straight line (with standard daily noise) took a noticeable downward turn - on all 5 masers. On 2013-10-03 05:33, Jim Palfreyman wrote: Noticed an above average bump in our H-Maser vs GPS graphs - from sites all over Australia. Recent coronal mass ejection or US government shutdown not updating GPS? Anyone else seen it? drop out gap between about 04.21-04.26 UTC? clockstats.20131003: 56568 15684.876 127.127.20.4 $GPRMC 042124 A ... 56568 16004.862 127.127.20.4 $GPRMC 042644 A ... peerstats.20131003: 56568 15684.876 127.127.20.4 961a -0.02270 ... 0.05344 56568 16004.862 127.127.20.4 961a -0.13150 ... 0.15721 loopstats.20131003: 56568 15684.876 -0.02270 0.899 0.07071 0.70 4 56568 16004.862 -0.13150 0.898 0.08830 0.000114 4 Did anyone else who tracks H-masers notice this as well? That’s a pretty small group Is it JPL making corrections? Le 10 oct. 2014 à 03:09, Bob Camp a écrit : GPS is steered by the Air Force last time I checked. A really good place to check is the NIST Time and Frequency pages that show both real time and historical data for each GPS sat compared to NIST time: http://www.nist.gov/pml/div688/grp40/gpsarchive.cfm Hopefully it’s accessible via that link from a variety of locations. Since the NIST data is independent of the steering (two different outfits involved) it should not be vulnerable to a “our ground segment broke and we steered everything to match” sort of error. On 2014-10-09 23:06, mike cook wrote: I remember Jim reported a similar issue back in october last year: That dates are close enough to make you wonder if it is not part of some cycle. From: http://www.usno.navy.mil/USNO/time/gps/gps-info GPS SYSTEM TIME GPS system time is given by its Composite Clock (CC). The CC or paper clock consists of all operational Monitor Station and satellite frequency standards. GPS system time, in turn, is referenced to the Master Clock (MC) at the USNO and steered to UTC(USNO) Because USNO is the official keeper of “time” in the US. NIST is the official for frequency. from which system time will not deviate by more than one microsecond. The exact difference is contained in the navigation message in the form of two constants, A0 and A1, giving the time difference and rate of system time against UTC(USNO,MC). Page also gives links to GPS time data ftp://tycho.usno.navy.mil/pub/gps/utcgps30.dat which shows a 2ns jump in UTC(USNO)-GPS smoothed over 2 days from Oct 7-8, but that appears normal; the 1ns differences from Oct 2-7 appear anomalous. Consider in all the data that it *is* coming from fairly normal receivers. They use good survey grade stuff, but it’s a receiver you could buy off the shelf. Pops do happen Looking at the NIST 10 min data, from Oct 3-8 the gap between GPS samples and NIST closed about 1.5ns/day, dropping now to about .5ns/day: the graph shows the values sliding down to the right, and now levelling off about zero So are NIST and USNO steering each other? All the data you see from NIST and USNO in terms of “what time is it” is the output of some *very* fancy filtering. They take a weighted set of inputs from a large number of sources. They also do a cross check through BIH to keep in synch worldwide. In the sense that BIH corrections get in the mix, everything is locked to everything. The GPS master clock is a similar thing. GPS master time (the ground clocks) are fed into a fancy software filter to come up with a local time estimate. That’s massaged to track USNO (more software). The ground estimate is used to look at and steer the satellite clocks through still another software filter. All of this stuff has crazy long memory in it, so a “once every three months” or even a “once a year” update of some sort is not at all out of the question. In a sense, leap seconds are a “once very rarely” correction to all this stuff. -- Take care. Thanks, Brian Inglis ___ 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 If there was no notice of a change on the various GPS / NIST / USNO / BIH web sites, I’d look for a paper at an upcoming conference. Depending on who did the bump (if there was one) and who was simply following the herd, that paper could pop up in a lot of different places. Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
Re: [time-nuts] Digital Mixing with a BeagleBone Black and D Flip Flop
Simon, Welcome to the tangential world. I'm sure the clean edge I saw was an aberration, perhaps analogous to phase locking in oscillators; I don't think it's desirable because common sense tells you that with imperfect clocks and small phase differences there are bound to be some number of glitches at each transition. I did nothing specific to eliminate the glitches, it just happened that the positive going transition was very clean but there's no reason I am aware of to suggest that one transition should be better in this respect than another. Perhaps the flip flop I was using had a shorter set-up time on negative to positive transitions than vice versa; the smaller the set-up time the more likely one is to capture borderline events? I seem to recall that Didier Juges and Bruce Griffiths had some discussions re DDMTD's (although I can't find it in the archives) but in any event you could do far worse than dropping them a note directly to ask them about their thoughts on the matter. I'm sorry I can't provide any analysis of your data; just not in my skill set. Perhaps Marcus or TVB could comment. Bob Darby On 10/10/2014 3:46 PM, Simon Marsh wrote: Bob, It's good to know someone else is trying this and it's not just me going off on a tangent somewhere. I'd be very interested in understanding how you'd set this up and how you'd got a nice clean rising edge. My understanding is that the 'glitches' occur because the clocks are being sampled at a higher resolution than the cycle to cycle noise inherent in both the clocks and the setup. Certainly, I don't expect any of the oscillators I have available to be perfectly stable at ~1E-12 resolution, I'm sure they are all over the place The clock phase noise shows up as fast transitions near the actual beat edge as the clocks wander backwards and forwards over a few cycles. I'm sure analysis of the glitches themselves would probably say quite a lot about the cycle to cycle noise. I've attached an example of the transitions near an edge for a random TCXO. The edge goes from 0 at the start to 1 at the end and shows noise over about 180 samples (@10mhz). This corresponds to about ± 5E-11. The crossing line of the zero one counts is where the edge is measured from the software point of view. ± 50ps sounds high to me, but I'm open to views as to whether that seems reasonable or just shows my shoddy setup ? For fun, also attached is plot of the transitions for a UBLOX8 GPS module outputing 10mhz. Compared to the TCXO that has about 10k transitions in a second's worth of data, the UBLOX module has over 1.3M (this is with a beat frequency of ~60hz). I think this is down to how the gps module is inserting/removing cycles to get 10mhz from its internal clock frequency (as has been discussed on here recently). Unfortunately, I don't have any expensive counters, that's part of my motivation for doing this, so I'm interested in ways that I can understand the noise floor. I tried passing one clock through a 74AC hex inverter and then measuring the phase between the inverted/non-inverted signals on the basis that this should be more or less constant and what I'd be measuring was noise. It's certainly a good way of measuring how long the wire was that I used to make the connection This seems to yield an ADEV of 5.92E-11 @ 1 sec, plots also attached. Interestingly the phase seems to drift over the measurement interval, I'm open to suggestions on this, but guess this may be temperature related ? (open on bench, non-airconditioned etc) If the plots don't come through as attached, they are also on google drive here: https://drive.google.com/open?id=0BzvFGRfj4aFkSEdYV3lXcmZIVTAauthuser=0 Cheers Simon On 10/10/2014 02:01, Robert Darby wrote: Simon, I breadboaded a set-up in March using 74AC74's and two 10 MHz Micro Crystal oscillators (5V square wave), one as the coherent source and one as the 10Hz offset clock. I had no glitch filtering as described in the article you cite (CERN's White Rabbit Project, sub nanosecond timing over ethernet) but found the positive zero crossing was very clean. The negative crossing not so much; no idea why one edge was clean and the other not. To ensure I only measured the rising clock edge and not the noise on the falling clock, I programmed ATiny's (digital 555?) to arm the D-flops only after a period of continuous low states. In any event, the lash up, as measure by a 5370, produced a clean linear noise floor of 8e-12 at 1s. I regret to note that's very slightly better than my results from the Bill Riley DMTD device. That's an indictment of my analog building skills, not his design. It's also nicely below a 5370 on it's own and needs only a simple 10 MHz counter for output. The zero crossing detectors for sine wave oscillator input will perhaps be more critical. This was encouraging enough that I thought I'd try to build an FPGA version of the same.
Re: [time-nuts] Digital Mixing with a BeagleBone Black and D Flip Flop
Hi If you are looking at the low frequency beat note out of a mixer and seeing multiple transitions on an edge - you filtering or your limiter are not up to the task. In most cases it’s the filter, but it can be either. Bob On Oct 11, 2014, at 9:10 AM, Robert Darby bobda...@triad.rr.com wrote: Simon, Welcome to the tangential world. I'm sure the clean edge I saw was an aberration, perhaps analogous to phase locking in oscillators; I don't think it's desirable because common sense tells you that with imperfect clocks and small phase differences there are bound to be some number of glitches at each transition. I did nothing specific to eliminate the glitches, it just happened that the positive going transition was very clean but there's no reason I am aware of to suggest that one transition should be better in this respect than another. Perhaps the flip flop I was using had a shorter set-up time on negative to positive transitions than vice versa; the smaller the set-up time the more likely one is to capture borderline events? I seem to recall that Didier Juges and Bruce Griffiths had some discussions re DDMTD's (although I can't find it in the archives) but in any event you could do far worse than dropping them a note directly to ask them about their thoughts on the matter. I'm sorry I can't provide any analysis of your data; just not in my skill set. Perhaps Marcus or TVB could comment. Bob Darby On 10/10/2014 3:46 PM, Simon Marsh wrote: Bob, It's good to know someone else is trying this and it's not just me going off on a tangent somewhere. I'd be very interested in understanding how you'd set this up and how you'd got a nice clean rising edge. My understanding is that the 'glitches' occur because the clocks are being sampled at a higher resolution than the cycle to cycle noise inherent in both the clocks and the setup. Certainly, I don't expect any of the oscillators I have available to be perfectly stable at ~1E-12 resolution, I'm sure they are all over the place The clock phase noise shows up as fast transitions near the actual beat edge as the clocks wander backwards and forwards over a few cycles. I'm sure analysis of the glitches themselves would probably say quite a lot about the cycle to cycle noise. I've attached an example of the transitions near an edge for a random TCXO. The edge goes from 0 at the start to 1 at the end and shows noise over about 180 samples (@10mhz). This corresponds to about ± 5E-11. The crossing line of the zero one counts is where the edge is measured from the software point of view. ± 50ps sounds high to me, but I'm open to views as to whether that seems reasonable or just shows my shoddy setup ? For fun, also attached is plot of the transitions for a UBLOX8 GPS module outputing 10mhz. Compared to the TCXO that has about 10k transitions in a second's worth of data, the UBLOX module has over 1.3M (this is with a beat frequency of ~60hz). I think this is down to how the gps module is inserting/removing cycles to get 10mhz from its internal clock frequency (as has been discussed on here recently). Unfortunately, I don't have any expensive counters, that's part of my motivation for doing this, so I'm interested in ways that I can understand the noise floor. I tried passing one clock through a 74AC hex inverter and then measuring the phase between the inverted/non-inverted signals on the basis that this should be more or less constant and what I'd be measuring was noise. It's certainly a good way of measuring how long the wire was that I used to make the connection This seems to yield an ADEV of 5.92E-11 @ 1 sec, plots also attached. Interestingly the phase seems to drift over the measurement interval, I'm open to suggestions on this, but guess this may be temperature related ? (open on bench, non-airconditioned etc) If the plots don't come through as attached, they are also on google drive here: https://drive.google.com/open?id=0BzvFGRfj4aFkSEdYV3lXcmZIVTAauthuser=0 Cheers Simon On 10/10/2014 02:01, Robert Darby wrote: Simon, I breadboaded a set-up in March using 74AC74's and two 10 MHz Micro Crystal oscillators (5V square wave), one as the coherent source and one as the 10Hz offset clock. I had no glitch filtering as described in the article you cite (CERN's White Rabbit Project, sub nanosecond timing over ethernet) but found the positive zero crossing was very clean. The negative crossing not so much; no idea why one edge was clean and the other not. To ensure I only measured the rising clock edge and not the noise on the falling clock, I programmed ATiny's (digital 555?) to arm the D-flops only after a period of continuous low states. In any event, the lash up, as measure by a 5370, produced a clean linear noise floor of 8e-12 at 1s. I regret to note that's very slightly better than my results
Re: [time-nuts] GPS jump
Hal, On 10/11/2014 08:49 AM, Hal Murray wrote: gign...@gmail.com said: Is it actually possible to phase lock two oscillators together cross the distance from DC to Colorado Springs? (2400 kilometers or so). ? I think so - if your clocks are stable enough. There is probably a simple rule for PLL stability based on round-trip-time and bandwidth (and other factors). Actually, the problem of mutual lock over distance was solved and described in the 80thies. I can dig up the article reference from one of my books if needed. 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] GPS jump
Hi To the extent that anything *is* locked, it’s been done for a lot longer than the 1980’s. Long before common view GPS, Loran-C observations (and corrections via clock trips) were used. You can look at it as a PLL, just a *very* fancy one with *very* long time constants. Bob On Oct 11, 2014, at 10:59 AM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Hal, On 10/11/2014 08:49 AM, Hal Murray wrote: gign...@gmail.com said: Is it actually possible to phase lock two oscillators together cross the distance from DC to Colorado Springs? (2400 kilometers or so). ? I think so - if your clocks are stable enough. There is probably a simple rule for PLL stability based on round-trip-time and bandwidth (and other factors). Actually, the problem of mutual lock over distance was solved and described in the 80thies. I can dig up the article reference from one of my books if needed. 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. ___ 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] locking oscillators - an increase in power and/or stability ?
I have been doing phase combining of power amplifiers for almost 30 years, professionally. If I could get 1200W by combining two 300W amplifiers, I would now be retired and very wealthy indeed. Unfortunately, there is no free lunch and unless somehow the Gun oscillators were delivering more power when connected to the magic T (maybe because of better matching) than when measured individually, combining two X W sources will only give you, at best, 2xX W, or 3dB more power. It does not matter what the combining structure is, magic T, coupler or else. Didier KO4BB On October 8, 2014 5:22:23 PM CDT, Bob Camp kb...@n1k.org wrote: HI In the case of a magic Tee or a normal power splitter (both passive devices), the current will not be limited by the combiner or the source. With a proper combiner, the source will always be running into 50 ohms. You will indeed get 6 db in the in phase sum case. Bob On Oct 8, 2014, at 4:46 PM, Dr. David Kirkby (Kirkby Microwave Ltd) drkir...@kirkbymicrowave.co.uk wrote: On 8 Oct 2014 20:26, Bob Camp kb...@n1k.org wrote: Hi It’s called injection locking. The two oscillators (or what ever) lock up at exactly the same frequency and some arbitrary phase. Depending on the amplitude and phase at the sum point, the result can be anything from +6 db to zero power. Anything that oscillates can injection lock if given the right feedback at the right point. The gotcha is that they are at the same frequency, so they add as voltages rather than power. In phase, equal amplitude, you get 6 db more power. Exactly 180 degrees out of phase and exactly equal power and you get nothing (no power at all) at the sum point. Off by a fraction of a degree or a fraction of a db and you still get roughly 6 db in the zero degree case. But while voltages could double, that is not going to happen if something limits the current. 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. -- 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] locking oscillators - an increase in power and/or stability ?
That would only work if the impedance of the source was much lower than the impedance of the load. That is extremely unlikely in high power systems (at least in well functioning high power systems), but I heard that modern LNAs do not always provide the best noise figure when matched, so maybe that was the reason for that observation? Didier KO4BB On October 8, 2014 2:07:31 PM CDT, cdel...@juno.com wrote: Hi, I came across this phenomena when transmitting with two 5KW transmitters via separate parabolic antennas to a satellite. If the phase of the TXs was correct the received signal at the satellite was 6db hotter! I thought at the time that it was due to the power adding in the voltage mode. For instance if you take a 1volt signal into 1 ohm you get 1 amp and 1 watt. but if you take two 1volt signals and add them to produce a 2 volt signal then you get 2 amps and 4 watts. Not sure if my logic is correct but the phenomena is real! Corby ___ 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.
[time-nuts] locking oscillators - an increase in power and/or stability ?
Came across this. Might be relevant. Cheers, Corby http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930008868.pdf a) Greater than 100% power combining efficiencies have been realized as predicted. This implies that the output power from the combiner is typically greater than the sum of the power available from individual devices. ___ 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] locking oscillators - an increase in power and/or stability ?
On 11 Oct 2014 16:25, Didier Juges shali...@gmail.com wrote: If I could get 1200W by combining two 300W amplifiers, I would now be retired and very wealthy indeed. Unfortunately, there is no free lunch and unless somehow the Gun oscillators were delivering more power when connected to the magic T (maybe because of better matching) than when measured individually, combining two X W sources will only give you, at best, 2xX W, or 3dB more power. I see you don't get something for nothing - we are not taking about perpetual motion. I can see a few possible explanations. 1) Instrumentation error. 2) Better match - but that seems unlikely as I would have expected people to have tried countless way to improve that. 3) Injection locking causes the Gunn diode to oscillate in a different way, perhaps using different energy levels in the doped semiconductor. The fact that they have become frequency locked, indicates that their mode of operation has changed - they are not operating in the way the text books say that they do. About 2 decades ago I did an MSc in microwaves optoelectronics. At that time I had a pretty good understanding of how Gunn diodes worked, but I have since forgotten the details. But it doesn't seem totally impossible that the mode of operation changes to one which is more efficient. It does not matter what the combining structure is, magic T, coupler or else. I understand what you are saying, but it is hard to dismiss the possibility it is true given several people have observed this. Just because it doesn't fit into our established theories, doesn't mean it can not happen. It is not breaking any laws of physics - the overall efficiency is well below 100%. Didier KO4BB Dave G8WRB. ___ 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] Digital Mixing with a BeagleBone Black and D Flip Flop
In this case, it seems reasonable that these multiple transitions are to be expected as there isn't any filtering that takes place in hardware prior to samples being captured by the BBB. The equivalent of the filtering/zero crossing detection takes place in software in the edge detection routine. Cheers Simon On 11/10/2014 15:19, Bob Camp wrote: Hi If you are looking at the low frequency beat note out of a mixer and seeing multiple transitions on an edge - you filtering or your limiter are not up to the task. In most cases it’s the filter, but it can be either. Bob On Oct 11, 2014, at 9:10 AM, Robert Darby bobda...@triad.rr.com wrote: Simon, Welcome to the tangential world. I'm sure the clean edge I saw was an aberration, perhaps analogous to phase locking in oscillators; I don't think it's desirable because common sense tells you that with imperfect clocks and small phase differences there are bound to be some number of glitches at each transition. I did nothing specific to eliminate the glitches, it just happened that the positive going transition was very clean but there's no reason I am aware of to suggest that one transition should be better in this respect than another. Perhaps the flip flop I was using had a shorter set-up time on negative to positive transitions than vice versa; the smaller the set-up time the more likely one is to capture borderline events? I seem to recall that Didier Juges and Bruce Griffiths had some discussions re DDMTD's (although I can't find it in the archives) but in any event you could do far worse than dropping them a note directly to ask them about their thoughts on the matter. I'm sorry I can't provide any analysis of your data; just not in my skill set. Perhaps Marcus or TVB could comment. Bob Darby On 10/10/2014 3:46 PM, Simon Marsh wrote: Bob, It's good to know someone else is trying this and it's not just me going off on a tangent somewhere. I'd be very interested in understanding how you'd set this up and how you'd got a nice clean rising edge. My understanding is that the 'glitches' occur because the clocks are being sampled at a higher resolution than the cycle to cycle noise inherent in both the clocks and the setup. Certainly, I don't expect any of the oscillators I have available to be perfectly stable at ~1E-12 resolution, I'm sure they are all over the place The clock phase noise shows up as fast transitions near the actual beat edge as the clocks wander backwards and forwards over a few cycles. I'm sure analysis of the glitches themselves would probably say quite a lot about the cycle to cycle noise. I've attached an example of the transitions near an edge for a random TCXO. The edge goes from 0 at the start to 1 at the end and shows noise over about 180 samples (@10mhz). This corresponds to about ± 5E-11. The crossing line of the zero one counts is where the edge is measured from the software point of view. ± 50ps sounds high to me, but I'm open to views as to whether that seems reasonable or just shows my shoddy setup ? For fun, also attached is plot of the transitions for a UBLOX8 GPS module outputing 10mhz. Compared to the TCXO that has about 10k transitions in a second's worth of data, the UBLOX module has over 1.3M (this is with a beat frequency of ~60hz). I think this is down to how the gps module is inserting/removing cycles to get 10mhz from its internal clock frequency (as has been discussed on here recently). Unfortunately, I don't have any expensive counters, that's part of my motivation for doing this, so I'm interested in ways that I can understand the noise floor. I tried passing one clock through a 74AC hex inverter and then measuring the phase between the inverted/non-inverted signals on the basis that this should be more or less constant and what I'd be measuring was noise. It's certainly a good way of measuring how long the wire was that I used to make the connection This seems to yield an ADEV of 5.92E-11 @ 1 sec, plots also attached. Interestingly the phase seems to drift over the measurement interval, I'm open to suggestions on this, but guess this may be temperature related ? (open on bench, non-airconditioned etc) If the plots don't come through as attached, they are also on google drive here: https://drive.google.com/open?id=0BzvFGRfj4aFkSEdYV3lXcmZIVTAauthuser=0 Cheers Simon On 10/10/2014 02:01, Robert Darby wrote: Simon, I breadboaded a set-up in March using 74AC74's and two 10 MHz Micro Crystal oscillators (5V square wave), one as the coherent source and one as the 10Hz offset clock. I had no glitch filtering as described in the article you cite (CERN's White Rabbit Project, sub nanosecond timing over ethernet) but found the positive zero crossing was very clean. The negative crossing not so much; no idea why one edge was clean and the other not. To ensure I only measured the rising clock edge and not the noise on the falling clock, I
Re: [time-nuts] HP10811-60212-B Pinouts.
Hi All, Yeah, that's the oscillator. The cables match the connector labels on the board. Same blue coax cables. Anyway, as this unit is missing the external oven controller, Is anyone aware of an aftermarket controller or a good reference for the controller required? I'm sure one can always build a controller, but buying something ready to go would be a better option! Thanks! Dan b...@evoria.net said: I found a picture that looks like your OCXO on Brooke Clarke's website. Maybe he has a schematic or pinouts for the oscillator. http://www.prc68.com/I/Images/Z3805A07b.jpg More info here: http://www.prc68.com/I/Z3805A.html The Z3805A is very similar to the Z3801A Brooke: typo in http://www.prc68.com/Alpha.shtml Down at the bottom, the link to the Z3805A page goes to file:///C:/Webdocs_Hosted/I/Z3805A.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] GPS jump
On 10/11/14, 8:08 AM, Bob Camp wrote: Hi To the extent that anything *is* locked, it’s been done for a lot longer than the 1980’s. Long before common view GPS, Loran-C observations (and corrections via clock trips) were used. You can look at it as a PLL, just a *very* fancy one with *very* long time constants. Bob It also depends on whether you need lock in real time or lock in post processing. VLBI is a good example of the latter, and was done in the early 70s to determine the position of the moon rover, for example. ___ 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] locking oscillators - an increase in power and/or stability ?
On 10/11/14, 9:00 AM, cdel...@juno.com wrote: Came across this. Might be relevant. Cheers, Corby http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930008868.pdf a) Greater than 100% power combining efficiencies have been realized as predicted. This implies that the output power from the combiner is typically greater than the sum of the power available from individual devices. Those are Indium Phosphide Gunn Oscillators which are highly nonlinear and have significant dynamic component to their Z. So you can't expect all the usual combining rules (which are typically based on constant impedances, etc.) This might be one of those optimize the dynamic match to suck more power out of the device kind of 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] HP10811-60212-B Pinouts.
Hi Dan, Didier's site is back up and this should give you a start: http://www.ko4bb.com/manuals/index.php?dir=05%29_GPS_Timing/Z3801/Z3801A_Schematic Bob From: d...@irtelemetrics.com d...@irtelemetrics.com To: time-nuts@febo.com Sent: Saturday, October 11, 2014 11:57 AM Subject: Re: [time-nuts] HP10811-60212-B Pinouts. Hi All, Yeah, that's the oscillator. The cables match the connector labels on the board. Same blue coax cables. Anyway, as this unit is missing the external oven controller, Is anyone aware of an aftermarket controller or a good reference for the controller required? I'm sure one can always build a controller, but buying something ready to go would be a better option! Thanks! Dan ___ 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] GPS jump
Hi The interesting thing about keeping ensembles of primary standards in line is that the boundary between “post processing” and “real time” blurs quite a bit. Looking at the papers, in many cases they are looking at all of what’s gone on over the last year or two and guessing at what will happen out to a few months from now. Bob On Oct 11, 2014, at 1:18 PM, Jim Lux jim...@earthlink.net wrote: On 10/11/14, 8:08 AM, Bob Camp wrote: Hi To the extent that anything *is* locked, it’s been done for a lot longer than the 1980’s. Long before common view GPS, Loran-C observations (and corrections via clock trips) were used. You can look at it as a PLL, just a *very* fancy one with *very* long time constants. Bob It also depends on whether you need lock in real time or lock in post processing. VLBI is a good example of the latter, and was done in the early 70s to determine the position of the moon rover, for example. ___ 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] Digital Mixing with a BeagleBone Black and D Flip Flop
Bob we are using digital mixers in some other applications but what surprised me is your comment on the Riley DMTD. We have a couple of slightly modified Riley's and see any where from 1.44 to 3.84 E-14 at 1 second. Bill also sows data below 1 E-13 at 1 second. Presently looking at braking the 1 E-14 level at the same time reducing cost. Bert Kehren. In a message dated 10/9/2014 9:01:24 P.M. Eastern Daylight Time, bobda...@triad.rr.com writes: Simon, I breadboaded a set-up in March using 74AC74's and two 10 MHz Micro Crystal oscillators (5V square wave), one as the coherent source and one as the 10Hz offset clock. I had no glitch filtering as described in the article you cite (CERN's White Rabbit Project, sub nanosecond timing over ethernet) but found the positive zero crossing was very clean. The negative crossing not so much; no idea why one edge was clean and the other not. To ensure I only measured the rising clock edge and not the noise on the falling clock, I programmed ATiny's (digital 555?) to arm the D-flops only after a period of continuous low states. In any event, the lash up, as measure by a 5370, produced a clean linear noise floor of 8e-12 at 1s. I regret to note that's very slightly better than my results from the Bill Riley DMTD device. That's an indictment of my analog building skills, not his design. It's also nicely below a 5370 on it's own and needs only a simple 10 MHz counter for output. The zero crossing detectors for sine wave oscillator input will perhaps be more critical. This was encouraging enough that I thought I'd try to build an FPGA version of the same. The DDMTD is temporarily on back burner while I try to get a four channel 1ns resolution time tagger running on the FPGA to use with the DMTD. Almost there. I look forward to hearing your results with the BBB; keep us posted. Bob Darby On 10/9/2014 1:34 AM, Andrew Rodland wrote: Simon, This is a fantastic idea and I have every intention of trying to replicate it at home with tools on hand. Thanks for sharing, and I hope you can show off some results. On Wed, Oct 8, 2014 at 1:09 PM, Simon Marsh subscripti...@burble.com wrote: I've been a lurker on time-nuts for a while, most of the discussion being way over my head, but I thought there may be interest in some proof of concept code I've written for simple digital hetrodyne mixing using just a BeagleBone Black and an external dual D Flip Flop. The idea is based on the following article which describes creating a digital DMTD with an FPGA for clocks @ 125mhz: http://www.ee.ucl.ac.uk/lcs/previous/LCS2011/LCS1136.pdf My setup follows the same principle, but scaled down to 10mhz to make it as simple as possible (and not require an FPGA). The hardware side is just a 74AC74 dual flip flop to sample the input clocks being tested. Instead of having a helper PLL for the mixer frequency, I simply have a 3rd, de-tuned oscillator. The output from the two flip-flops together with the mixer clock are fed to the BBB. On the BBB, the approach is to do as little as possible in real time using a PRU core, and then post-process on the ARM core afterwards. The BBB PRU has a 16-bit, asynchronous, parallel, capture mode, where 16 GPIO pins can be latched based on an external clock (described in section 4.4.1.2.3.2 of the TRM for those interested). In this case, the external clock is the mixer oscillator. All the PRU needs to do is wait for the sample to take place, read the GPIOs and store the results in main memory. The PRU is plenty fast enough to capture samples @10mhz and, in theory at least, each PRU could sample up to 16 clocks simultaneously (depending on whether the relevant GPIO pins were free). Once the sampling is complete, the ARM core can process the results in its own time, and this includes any more complicated algorithms for de-glitching etc The theoretical minimum time resolution depends on the beat frequency and is described in the article, for example with a beat frequency of 50 hz the minimum resolution is 50 / (1000 - 50)*1000 = ~5E-13. In practice the available accuracy is determined by the stability of the mixer clock and noise of the setup. The impact of this noise is described in the article as glitching and there are some suggested ways for processing this out. I'm trying this on an open bench, with basic oscillators, using pluggable breadboard and lots of hanging wires, I'm not at risk of getting near the theoretical limit quite yet :) Note that the BBB itself has no impact on the accuracy or noise of the raw data. Once the input is latched at the flip-flop, the only bit of critical timing required is to ensure that samples can be captured fast enough and that the flip-flop state is captured when it is stable (i.e. not transitioning). I make no excuses that this is very
Re: [time-nuts] Digital Mixing with a BeagleBone Black and D Flip Flop
Yeah, breaks my heart but I'm not real good (try real bad) at troubleshooting electronics (so why am i here?). As I noted in my earlier post, the issue lies in my construction and lack of knowledge re electronic fundamentals. I have the greatest respect for Mr. Riley and I do not want my ineptitude to in any way reflect on his design. All problems with my DMTD are of my making, not his. bob On 10/11/2014 3:10 PM, Bert Kehren via time-nuts wrote: Bob we are using digital mixers in some other applications but what surprised me is your comment on the Riley DMTD. We have a couple of slightly modified Riley's and see any where from 1.44 to 3.84 E-14 at 1 second. Bill also sows data below 1 E-13 at 1 second. Presently looking at braking the 1 E-14 level at the same time reducing cost. Bert Kehren. In a message dated 10/9/2014 9:01:24 P.M. Eastern Daylight Time, bobda...@triad.rr.com writes: Simon, I breadboaded a set-up in March using 74AC74's and two 10 MHz Micro Crystal oscillators (5V square wave), one as the coherent source and one as the 10Hz offset clock. I had no glitch filtering as described in the article you cite (CERN's White Rabbit Project, sub nanosecond timing over ethernet) but found the positive zero crossing was very clean. The negative crossing not so much; no idea why one edge was clean and the other not. To ensure I only measured the rising clock edge and not the noise on the falling clock, I programmed ATiny's (digital 555?) to arm the D-flops only after a period of continuous low states. In any event, the lash up, as measure by a 5370, produced a clean linear noise floor of 8e-12 at 1s. I regret to note that's very slightly better than my results from the Bill Riley DMTD device. That's an indictment of my analog building skills, not his design. It's also nicely below a 5370 on it's own and needs only a simple 10 MHz counter for output. The zero crossing detectors for sine wave oscillator input will perhaps be more critical. This was encouraging enough that I thought I'd try to build an FPGA version of the same. The DDMTD is temporarily on back burner while I try to get a four channel 1ns resolution time tagger running on the FPGA to use with the DMTD. Almost there. I look forward to hearing your results with the BBB; keep us posted. Bob Darby On 10/9/2014 1:34 AM, Andrew Rodland wrote: Simon, This is a fantastic idea and I have every intention of trying to replicate it at home with tools on hand. Thanks for sharing, and I hope you can show off some results. On Wed, Oct 8, 2014 at 1:09 PM, Simon Marsh subscripti...@burble.com wrote: I've been a lurker on time-nuts for a while, most of the discussion being way over my head, but I thought there may be interest in some proof of concept code I've written for simple digital hetrodyne mixing using just a BeagleBone Black and an external dual D Flip Flop. The idea is based on the following article which describes creating a digital DMTD with an FPGA for clocks @ 125mhz: http://www.ee.ucl.ac.uk/lcs/previous/LCS2011/LCS1136.pdf My setup follows the same principle, but scaled down to 10mhz to make it as simple as possible (and not require an FPGA). The hardware side is just a 74AC74 dual flip flop to sample the input clocks being tested. Instead of having a helper PLL for the mixer frequency, I simply have a 3rd, de-tuned oscillator. The output from the two flip-flops together with the mixer clock are fed to the BBB. On the BBB, the approach is to do as little as possible in real time using a PRU core, and then post-process on the ARM core afterwards. The BBB PRU has a 16-bit, asynchronous, parallel, capture mode, where 16 GPIO pins can be latched based on an external clock (described in section 4.4.1.2.3.2 of the TRM for those interested). In this case, the external clock is the mixer oscillator. All the PRU needs to do is wait for the sample to take place, read the GPIOs and store the results in main memory. The PRU is plenty fast enough to capture samples @10mhz and, in theory at least, each PRU could sample up to 16 clocks simultaneously (depending on whether the relevant GPIO pins were free). Once the sampling is complete, the ARM core can process the results in its own time, and this includes any more complicated algorithms for de-glitching etc The theoretical minimum time resolution depends on the beat frequency and is described in the article, for example with a beat frequency of 50 hz the minimum resolution is 50 / (1000 - 50)*1000 = ~5E-13. In practice the available accuracy is determined by the stability of the mixer clock and noise of the setup. The impact of this noise is described in the article as glitching and there are some suggested ways for processing this out. I'm trying this on an open bench, with basic oscillators, using pluggable breadboard and lots of hanging wires, I'm not at
Re: [time-nuts] Digital Mixing with a BeagleBone Black and D Flip Flop
Simon, If I can rephrase your first post, you plan to capture the state transitions along with their timing and subsequently post-process them to determine the time from one zero-crossing to another. Each zero-crossing is the sum of number of closely spaced state changes (glitches) and some algorithm can be used to determine when the real zero-crossing occurred. Given the low speed of the clock, a deep memory one bit data logger would suffice for each channel. Alternately, you can store time tags for each state transition; the time being measured in offset clock cycles. This reduces the device to an offset clock, analog to digital conversion for sine wave inputs, at least two d-flops, and the BBB for data capture and analysis. Correct? The glitches are to be expected and, as I noted, the absence of them on the negative to positive transition of my breadboarded set-up made me suspect the accuracy but also made it easy to get a back of the envelop noise floor number that should only get better, provide the de-glitch filter is robust. Just as another thought, an FTDI asynchronous fifo can move 10 MB/s and a synchronous fifo can move 60 MB/s. You could probably capture the D-flop outputs directly through a USB port and process the byte wide stream in real time. But that's what the BBB's going to do in any case. As I mentioned, I want to try this in an fpga and the filter is the only hard part there. I'm thinking a state machine that first establishes a stable low state, time tags the first positive transition and then looks for some number of stable high states. With a time tag at that point, it's easy to work back to the last positive transition and establish the mean time. I'm still trying to get my head around how I can do the zero count filter but hopefully it will come. The reason the fpga is attractive is because a $40 Papilio includes the D-Flops and is largely self contained. Add a wing pad with the input conversion and your beat clock and you're good to go. bob On 10/11/2014 11:17 AM, Simon Marsh wrote: In this case, it seems reasonable that these multiple transitions are to be expected as there isn't any filtering that takes place in hardware prior to samples being captured by the BBB. The equivalent of the filtering/zero crossing detection takes place in software in the edge detection routine. Cheers Simon On 11/10/2014 15:19, Bob Camp wrote: Hi If you are looking at the low frequency beat note out of a mixer and seeing multiple transitions on an edge - you filtering or your limiter are not up to the task. In most cases it’s the filter, but it can be either. Bob On Oct 11, 2014, at 9:10 AM, Robert Darby bobda...@triad.rr.com wrote: Simon, Welcome to the tangential world. I'm sure the clean edge I saw was an aberration, perhaps analogous to phase locking in oscillators; I don't think it's desirable because common sense tells you that with imperfect clocks and small phase differences there are bound to be some number of glitches at each transition. I did nothing specific to eliminate the glitches, it just happened that the positive going transition was very clean but there's no reason I am aware of to suggest that one transition should be better in this respect than another. Perhaps the flip flop I was using had a shorter set-up time on negative to positive transitions than vice versa; the smaller the set-up time the more likely one is to capture borderline events? I seem to recall that Didier Juges and Bruce Griffiths had some discussions re DDMTD's (although I can't find it in the archives) but in any event you could do far worse than dropping them a note directly to ask them about their thoughts on the matter. I'm sorry I can't provide any analysis of your data; just not in my skill set. Perhaps Marcus or TVB could comment. Bob Darby On 10/10/2014 3:46 PM, Simon Marsh wrote: Bob, It's good to know someone else is trying this and it's not just me going off on a tangent somewhere. I'd be very interested in understanding how you'd set this up and how you'd got a nice clean rising edge. My understanding is that the 'glitches' occur because the clocks are being sampled at a higher resolution than the cycle to cycle noise inherent in both the clocks and the setup. Certainly, I don't expect any of the oscillators I have available to be perfectly stable at ~1E-12 resolution, I'm sure they are all over the place The clock phase noise shows up as fast transitions near the actual beat edge as the clocks wander backwards and forwards over a few cycles. I'm sure analysis of the glitches themselves would probably say quite a lot about the cycle to cycle noise. I've attached an example of the transitions near an edge for a random TCXO. The edge goes from 0 at the start to 1 at the end and shows noise over about 180 samples (@10mhz). This corresponds to about ± 5E-11. The crossing line of the zero one
Re: [time-nuts] locking oscillators - an increase in power and/or stability ?
Perhaps this is useful Microwave oscillators will change in both power output and frequency as a function of the load impedance. This was first used to characterize magnetrons and klystrons. When plotted on a Smith Chart it is called a Rieke Diagram. I later used it with Gunn Diodes. You can make a considerable difference in the power output and immunity to load pulling of the frequency by adjusting the output coupling from the waveguide cavity. I used thin irises of varying diameter inserted between waveguide flanges to do this easily. When the power is greatest, the load pull is worst. If you provide a perfect match with a slide screw tuner, you get all the power you can, and then there is not enough left in the cavity to sustain oscillation. Guess what - it stops. I believe what you are seeing can be explained by the differing effects of changes in load impedance upon the oscillators. These will always be present of with any form of summing device unless a ferrite isolator with a very high degree of isolation (40+ dB) is used on each source before the summing device. john c roos k6iql -Original Message- From: time-nuts-request time-nuts-requ...@febo.com To: time-nuts time-nuts@febo.com Sent: Sat, Oct 11, 2014 11:50 am Subject: time-nuts Digest, Vol 123, Issue 42 Send time-nuts mailing list submissions to time-nuts@febo.com To subscribe or unsubscribe via the World Wide Web, visit https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts or, via email, send a message with subject or body 'help' to time-nuts-requ...@febo.com You can reach the person managing the list at time-nuts-ow...@febo.com When replying, please edit your Subject line so it is more specific than Re: Contents of time-nuts digest... Today's Topics: 1. locking oscillators - an increase in power and/or stability ? (cdel...@juno.com) 2. Re: locking oscillators - an increase in power and/or stability ? (Dr. David Kirkby (Kirkby Microwave Ltd)) 3. Re: Digital Mixing with a BeagleBone Black and D Flip Flop (Simon Marsh) 4. Re: HP10811-60212-B Pinouts. (d...@irtelemetrics.com) 5. Re: GPS jump (Jim Lux) 6. Re: locking oscillators - an increase in power and/or stability ? (Jim Lux) 7. Re: HP10811-60212-B Pinouts. (Bob Stewart) -- Message: 1 Date: Sat, 11 Oct 2014 09:00:28 -0700 From: cdel...@juno.com To: time-nuts@febo.com Subject: [time-nuts] locking oscillators - an increase in power and/or stability ? Message-ID: aablduxdnahw5...@smtpout02.dca.untd.com Content-Type: text/plain; charset=us-ascii Came across this. Might be relevant. Cheers, Corby http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930008868.pdf a) Greater than 100% power combining efficiencies have been realized as predicted. This implies that the output power from the combiner is typically greater than the sum of the power available from individual devices. -- Message: 2 Date: Sat, 11 Oct 2014 17:41:12 +0100 From: Dr. David Kirkby (Kirkby Microwave Ltd) drkir...@kirkbymicrowave.co.uk To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] locking oscillators - an increase in power and/or stability ? Message-ID: canx10hdwpkrjuachzbd1r3hdqvwhwo5ezq1ykvpysuhdakh...@mail.gmail.com Content-Type: text/plain; charset=UTF-8 On 11 Oct 2014 16:25, Didier Juges shali...@gmail.com wrote: If I could get 1200W by combining two 300W amplifiers, I would now be retired and very wealthy indeed. Unfortunately, there is no free lunch and unless somehow the Gun oscillators were delivering more power when connected to the magic T (maybe because of better matching) than when measured individually, combining two X W sources will only give you, at best, 2xX W, or 3dB more power. I see you don't get something for nothing - we are not taking about perpetual motion. I can see a few possible explanations. 1) Instrumentation error. 2) Better match - but that seems unlikely as I would have expected people to have tried countless way to improve that. 3) Injection locking causes the Gunn diode to oscillate in a different way, perhaps using different energy levels in the doped semiconductor. The fact that they have become frequency locked, indicates that their mode of operation has changed - they are not operating in the way the text books say that they do. About 2 decades ago I did an MSc in microwaves optoelectronics. At that time I had a pretty good understanding of how Gunn diodes worked, but I have since forgotten the details. But it doesn't seem totally impossible that the mode of operation changes to one which is more efficient. It does not matter what the combining structure is, magic T, coupler or else. I understand what you are saying, but it is hard to dismiss the possibility
Re: [time-nuts] Digital Mixing with a BeagleBone Black and D Flip Flop
Hi Your glitches are (in part) coming from the 20 MHz (10 + 10) component on the mixed signal. Since they have no direct relation to the beat note, filtering them after limiting is not a simple task. It is far easier to keep filter the signal pre-limit than to do so post limit. The other component of the glitches is related to the limiting process. The paper by Collins is a good one to read for information on gain, bandwidth and the limiting process. Again, there is very little you can do “post limit” to sort things out. None of the zero crossings you are getting may be “correct”. It’s not simply a process of picking one out of the group. —— Some math: You have two 10 MHz signals and a (say) 10 Hz beat note. You are looking for 1x10^-13. You get 1x10^-6 from the downconversion. You need to get 1x10^-7 out of the beat note. Put another way, 1x10^-13 at 10 MHz is 1x10^-5 Hz. If your beat note is 3 V p-p, it will cover 6V every 1/10 second. It’s about 1.2X faster than a triangle wave as it zero crosses (memory may be failing me here), so that makes it equal to a 7.2V triangle excursion. 1x10^-6 of 7.2V is 7.2 microvolts. That’s how accurate your limiter / filter combination needs to be, pre-limiting. It can be in a fairly narrow bandwidth, so it’s not quite as daunting as a radio front end. Since you have a very large signal, and very small noise, the normal “dithering will help me” effect of the noise can not be counted on. The thing you *want* to come up with is essentially a random signal (ADEV), so massive filtering will not do the trick either. Bob On Oct 11, 2014, at 3:33 PM, Robert Darby bobda...@triad.rr.com wrote: Simon, If I can rephrase your first post, you plan to capture the state transitions along with their timing and subsequently post-process them to determine the time from one zero-crossing to another. Each zero-crossing is the sum of number of closely spaced state changes (glitches) and some algorithm can be used to determine when the real zero-crossing occurred. Given the low speed of the clock, a deep memory one bit data logger would suffice for each channel. Alternately, you can store time tags for each state transition; the time being measured in offset clock cycles. This reduces the device to an offset clock, analog to digital conversion for sine wave inputs, at least two d-flops, and the BBB for data capture and analysis. Correct? The glitches are to be expected and, as I noted, the absence of them on the negative to positive transition of my breadboarded set-up made me suspect the accuracy but also made it easy to get a back of the envelop noise floor number that should only get better, provide the de-glitch filter is robust. Just as another thought, an FTDI asynchronous fifo can move 10 MB/s and a synchronous fifo can move 60 MB/s. You could probably capture the D-flop outputs directly through a USB port and process the byte wide stream in real time. But that's what the BBB's going to do in any case. As I mentioned, I want to try this in an fpga and the filter is the only hard part there. I'm thinking a state machine that first establishes a stable low state, time tags the first positive transition and then looks for some number of stable high states. With a time tag at that point, it's easy to work back to the last positive transition and establish the mean time. I'm still trying to get my head around how I can do the zero count filter but hopefully it will come. The reason the fpga is attractive is because a $40 Papilio includes the D-Flops and is largely self contained. Add a wing pad with the input conversion and your beat clock and you're good to go. bob On 10/11/2014 11:17 AM, Simon Marsh wrote: In this case, it seems reasonable that these multiple transitions are to be expected as there isn't any filtering that takes place in hardware prior to samples being captured by the BBB. The equivalent of the filtering/zero crossing detection takes place in software in the edge detection routine. Cheers Simon On 11/10/2014 15:19, Bob Camp wrote: Hi If you are looking at the low frequency beat note out of a mixer and seeing multiple transitions on an edge - you filtering or your limiter are not up to the task. In most cases it’s the filter, but it can be either. Bob On Oct 11, 2014, at 9:10 AM, Robert Darby bobda...@triad.rr.com wrote: Simon, Welcome to the tangential world. I'm sure the clean edge I saw was an aberration, perhaps analogous to phase locking in oscillators; I don't think it's desirable because common sense tells you that with imperfect clocks and small phase differences there are bound to be some number of glitches at each transition. I did nothing specific to eliminate the glitches, it just happened that the positive going transition was very clean but there's no reason I am aware of to suggest that
[time-nuts] F*watch
Friends, This is a GPS watch we designed after working hours as a surprise gift for a colleague who just retired: http://www.ohwr.org/projects/f-watch/wiki It's as free-as-in-freedom as we could make it: schematics, layout, case and code, all using free tools. Cheers, Javier ___ 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] Sun Outage
Jim Lux wrote: WHy yes they do: that's what weather radar is. It detects the reflections from the rain drops or ice crystals in the storms. ... But radar is much different than passively receiving known radio signals that penetrate the atmosphere from above. Conceivably one could have hundreds of small receivers, scattered around within the range of one WX radar. Much less cost than the radar, and no emissions so no need to license it. I don't know if it matters but they measure transmission, not scattering and reflectivity, and they look at the droplets from below, not the side. With the proliferation of personal weather stations, it seems like another source of information that could be exploited cheaply. Andy ___ 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] F*watch
On Sat, Oct 11, 2014 at 1:50 PM, Javier Serrano javier.serrano.par...@gmail.com wrote: It's as free-as-in-freedom as we could make it: schematics, layout, case and code, all using free tools. That is really the best part. But I wonder what it would cost to build a copy using your design files. Or what would it cost to build a run of say one dozen?Apple prices their watch at $350 which at first seemed really high but then I started thinking if that was a high price or not -- 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] FE-5680 Linux command line tool
It's a chip (PSD813F) which has 1MBit flash, 16Kbit SRAM and 256Kbit EEPROM. It's old school with parallel data/address bus and all that :) It does have JTAG. Regards, Tom On Sat, Oct 11, 2014 at 7:45 AM, Didier Juges shali...@gmail.com wrote: Most EEPROMs have I2C or SPI interfaces. Some Flash chips have JTAG. Didier KO4BB On October 10, 2014 4:47:19 PM CDT, Tom Wimmenhove tom.wimmenh...@gmail.com wrote: Thanks Joe! I don't have the clip-ons but of course I could get them. I know the chip has a JTAG interface, but I've only used JTAG with chips that came with a programmer and software :) (except with OpenOCD over parport once, but that was in the stone age). Another question about the EEPROM dump Elio Corbolante. The chip has a 256Kbit (32KB) EEPROM and the dump is 160K: -rw-rw-r-- 1 tom tom 160K nov 8 2012 FE5680A_EEPROM.bin Which part in this dump is the actual data from the EEPROM? Thanks in advance. Regards, Tom On Fri, Oct 10, 2014 at 12:21 PM, Joseph Gray jg...@zianet.com wrote: I don't know how crowded the board is, but I would use an SMD DIP clip instead of unsoldering the chip. Joe Gray W5JG On Oct 10, 2014 8:30 AM, Tom Wimmenhove tom.wimmenh...@gmail.com wrote: I recently came across a thread on this list about undocumented FE5680 commands. I have been using a little linux command line tool I wrote years ago for tuning the unit and decided to add these commands to it. Since this mailing list was the place I found the unit (someone linked to an ebay seller) I figured I' d join the list and throw it on here :) http://www.tomwimmenhove.com/otherstuff/fe5680-0.2.tgz Now, the bad news. I had my unit running overnight while logging the serial command output that reads the ADC, and in the morning it was no longer locked. The 10MHz signal disappears about 5 seconds after power-on, and programmed offset was somehow reset to zero (it had been set to -645). So it appears as if the internal EEPROM has been corrupted. I read a post from Elio Corbolante where he posted EEPROM and firmware dumps. Anyone have any idea on how to re-write this firmware back into the EEPROM by hand (would this be possible through JTAG, or do I actually have to solder the chip out of there? :) ) Or maybe there's someone willing to sell their broken unit I could take the chip out of? Regards, Tom ___ 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. -- 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. ___ 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] Digital Mixing with a BeagleBone Black and D Flip Flop
I (mostly) understand this when considering an analogue mixer, but I'm lost on whether there are any similar effects going on with a digital signal ? TBH, I'm not really sure 'mixing' is the right phrase in the digital case, and my apologies if I got that wrong. What's actually going on is sampling one (digital) signal at a rate close to the signal frequency. This gives a vernier effect and the result is a purely digital set of pulses at the beat frequency, aligned to when the signal and sample clock are in phase. It does not have a high frequency component to filter out. Cheers Simon On 11/10/2014 21:11, Bob Camp wrote: Hi Your glitches are (in part) coming from the 20 MHz (10 + 10) component on the mixed signal. Since they have no direct relation to the beat note, filtering them after limiting is not a simple task. It is far easier to keep filter the signal pre-limit than to do so post limit. The other component of the glitches is related to the limiting process. The paper by Collins is a good one to read for information on gain, bandwidth and the limiting process. Again, there is very little you can do “post limit” to sort things out. None of the zero crossings you are getting may be “correct”. It’s not simply a process of picking one out of the group. —— Some math: You have two 10 MHz signals and a (say) 10 Hz beat note. You are looking for 1x10^-13. You get 1x10^-6 from the downconversion. You need to get 1x10^-7 out of the beat note. Put another way, 1x10^-13 at 10 MHz is 1x10^-5 Hz. If your beat note is 3 V p-p, it will cover 6V every 1/10 second. It’s about 1.2X faster than a triangle wave as it zero crosses (memory may be failing me here), so that makes it equal to a 7.2V triangle excursion. 1x10^-6 of 7.2V is 7.2 microvolts. That’s how accurate your limiter / filter combination needs to be, pre-limiting. It can be in a fairly narrow bandwidth, so it’s not quite as daunting as a radio front end. Since you have a very large signal, and very small noise, the normal “dithering will help me” effect of the noise can not be counted on. The thing you *want* to come up with is essentially a random signal (ADEV), so massive filtering will not do the trick either. Bob On Oct 11, 2014, at 3:33 PM, Robert Darby bobda...@triad.rr.com wrote: ___ 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] Digital Mixing with a BeagleBone Black and D Flip Flop
On 11/10/2014 20:33, Robert Darby wrote: If I can rephrase your first post, you plan to capture the state transitions along with their timing and subsequently post-process them to determine the time from one zero-crossing to another. Each zero-crossing is the sum of number of closely spaced state changes (glitches) and some algorithm can be used to determine when the real zero-crossing occurred. Given the low speed of the clock, a deep memory one bit data logger would suffice for each channel. Alternately, you can store time tags for each state transition; the time being measured in offset clock cycles. Spot on, and indeed, the code I posted uses the one bit data logger idea. I intend to replace with time tagging to save some memory, save some ARM CPU time and enabling continuous logging. This reduces the device to an offset clock, analog to digital conversion for sine wave inputs, at least two d-flops, and the BBB for data capture and analysis. Correct? Yes, exactly. Of course, it also needs a bunch of software to do the processing. Just as another thought, an FTDI asynchronous fifo can move 10 MB/s and a synchronous fifo can move 60 MB/s. You could probably capture the D-flop outputs directly through a USB port and process the byte wide stream in real time. But that's what the BBB's going to do in any case. Interesting idea, but yes again, this is what I have the PRU on the BBB doing. As I mentioned, I want to try this in an fpga and the filter is the only hard part there. I'm thinking a state machine that first establishes a stable low state, time tags the first positive transition and then looks for some number of stable high states. With a time tag at that point, it's easy to work back to the last positive transition and establish the mean time. I'm still trying to get my head around how I can do the zero count filter but hopefully it will come. The reason the fpga is attractive is because a $40 Papilio includes the D-Flops and is largely self contained. Add a wing pad with the input conversion and your beat clock and you're good to go. I have a Papilio around somewhere too, but admit I find it easier messing around in software. Are you intending to output time stamped edges (or phase ?) from FPGA and then log/post-process somewhere else ? I used the zero count method, but no doubt this was easier in C than it will be on an FPGA. The paper I linked to has some discussion on a few algorithms, and they think the zero count is better than a mean. I'm not one to argue with clever folks at CERN, but I think it will be interesting to see if I can get to the point of showing if there is actually a difference at my scale, or even whether there are some smarter approaches when having the luxury of implementing in software. All I did was identify the first transition after a stable period and then count ones and zeros until ones zeros. The only gotcha is that (by definition) the first transition after a bunch of zeros will always be a one so you have to make sure you count the next set of zeros before checking if ones zeros (otherwise, of course, ones will always be zero on the first transition). This also means you need to have a limit built in for when there are no glitches (i.e. no zeros arrive before you determine the number of ones means you are in a new stable period). I'd be very interested at what you intend to do for the input conversion. Getting the signal squared up and delivered to the D-flop would seem to the hard part and where all the noise will be. Once you have a digital signal at the flip flop its downhill all the way. bob [snipped] Cheers Simon ___ 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] Digital Mixing with a BeagleBone Black and D Flip Flop
Hi The mixer you are using will give you a sine wave output *if* it’s properly filtered. A mixer is a mixer. Bob On Oct 11, 2014, at 6:31 PM, Simon Marsh subscripti...@burble.com wrote: I (mostly) understand this when considering an analogue mixer, but I'm lost on whether there are any similar effects going on with a digital signal ? TBH, I'm not really sure 'mixing' is the right phrase in the digital case, and my apologies if I got that wrong. What's actually going on is sampling one (digital) signal at a rate close to the signal frequency. This gives a vernier effect and the result is a purely digital set of pulses at the beat frequency, aligned to when the signal and sample clock are in phase. It does not have a high frequency component to filter out. Cheers Simon On 11/10/2014 21:11, Bob Camp wrote: Hi Your glitches are (in part) coming from the 20 MHz (10 + 10) component on the mixed signal. Since they have no direct relation to the beat note, filtering them after limiting is not a simple task. It is far easier to keep filter the signal pre-limit than to do so post limit. The other component of the glitches is related to the limiting process. The paper by Collins is a good one to read for information on gain, bandwidth and the limiting process. Again, there is very little you can do “post limit” to sort things out. None of the zero crossings you are getting may be “correct”. It’s not simply a process of picking one out of the group. —— Some math: You have two 10 MHz signals and a (say) 10 Hz beat note. You are looking for 1x10^-13. You get 1x10^-6 from the downconversion. You need to get 1x10^-7 out of the beat note. Put another way, 1x10^-13 at 10 MHz is 1x10^-5 Hz. If your beat note is 3 V p-p, it will cover 6V every 1/10 second. It’s about 1.2X faster than a triangle wave as it zero crosses (memory may be failing me here), so that makes it equal to a 7.2V triangle excursion. 1x10^-6 of 7.2V is 7.2 microvolts. That’s how accurate your limiter / filter combination needs to be, pre-limiting. It can be in a fairly narrow bandwidth, so it’s not quite as daunting as a radio front end. Since you have a very large signal, and very small noise, the normal “dithering will help me” effect of the noise can not be counted on. The thing you *want* to come up with is essentially a random signal (ADEV), so massive filtering will not do the trick either. Bob On Oct 11, 2014, at 3:33 PM, Robert Darby bobda...@triad.rr.com wrote: ___ 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] Digital Mixing with a BeagleBone Black and D Flip Flop
Hi Ok, a little more data: You can hook your flip flop up as a sampler or as a full blown mixer. Hooked up as a full blown mixer, you get the 20 MHz and 10 Hz signals. You also get more resolution on the 10 Hz. Either way, the 10 Hz is still a beat note. In the case of a sampler, the filter is there for edge jitter. With a sampler, your data is only modulo 100 ns. With a 100 ms beat note period, you only get 1x10^-6 at best. That’s very different than what you get with the same chip used as a mixer (or an XOR gate). The true mixer connection gives you data the instant the edge changes. The sampler goes to sleep and lets you know up to 100 ns later ... Bob On Oct 11, 2014, at 6:31 PM, Simon Marsh subscripti...@burble.com wrote: I (mostly) understand this when considering an analogue mixer, but I'm lost on whether there are any similar effects going on with a digital signal ? TBH, I'm not really sure 'mixing' is the right phrase in the digital case, and my apologies if I got that wrong. What's actually going on is sampling one (digital) signal at a rate close to the signal frequency. This gives a vernier effect and the result is a purely digital set of pulses at the beat frequency, aligned to when the signal and sample clock are in phase. It does not have a high frequency component to filter out. Cheers Simon On 11/10/2014 21:11, Bob Camp wrote: Hi Your glitches are (in part) coming from the 20 MHz (10 + 10) component on the mixed signal. Since they have no direct relation to the beat note, filtering them after limiting is not a simple task. It is far easier to keep filter the signal pre-limit than to do so post limit. The other component of the glitches is related to the limiting process. The paper by Collins is a good one to read for information on gain, bandwidth and the limiting process. Again, there is very little you can do “post limit” to sort things out. None of the zero crossings you are getting may be “correct”. It’s not simply a process of picking one out of the group. —— Some math: You have two 10 MHz signals and a (say) 10 Hz beat note. You are looking for 1x10^-13. You get 1x10^-6 from the downconversion. You need to get 1x10^-7 out of the beat note. Put another way, 1x10^-13 at 10 MHz is 1x10^-5 Hz. If your beat note is 3 V p-p, it will cover 6V every 1/10 second. It’s about 1.2X faster than a triangle wave as it zero crosses (memory may be failing me here), so that makes it equal to a 7.2V triangle excursion. 1x10^-6 of 7.2V is 7.2 microvolts. That’s how accurate your limiter / filter combination needs to be, pre-limiting. It can be in a fairly narrow bandwidth, so it’s not quite as daunting as a radio front end. Since you have a very large signal, and very small noise, the normal “dithering will help me” effect of the noise can not be counted on. The thing you *want* to come up with is essentially a random signal (ADEV), so massive filtering will not do the trick either. Bob On Oct 11, 2014, at 3:33 PM, Robert Darby bobda...@triad.rr.com wrote: ___ 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] TM500/TM5000/HP-5370 Extender cables and cards
The TM500/5000 and HP5370 extender kits are now available (actually they were ready a few weeks ago, but I was going to be out of town and did not want to leave people hanging).Prices are:HP5370 extender card kit - has 2 x 36 pin extenders and 1 x 44 pin extender. $30 setTektronix TM500/TM5000 module extender cable kit - $20Tektronix TM5000 GPIB extender cable (assembled) $20US shipping is $6 for any number of kits. International shipping is $15 for any number of kits. If you need international tracking they must go registered mail which adds another $15 (and slows down the mail) or express mail which is stupid expensive. All kits include everything you need to get going except solder and basic tools.Email me for my Paypal address.The HP5370 extenders are 5 inches long.The TM500 kits include a pair of 17 40 pin IDE ribbon cables. You may want to use your own, longer cables. The TM5000 GPIB cable is around 28 long.Remember that some TM500/5000 modules require 2 or 3 extender cables... I even have one that needs 4, but it is a one-off custom design. ___ 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] Digital Mixing with a BeagleBone Black and D Flip Flop
Bob Camp, Bob, Simon is talking about the sampler versus a true mixer. This is the idea I asked you about some months ago when I asked about how the digital filter functions. You were kind to explain the filter method in terms of buckets. You are of course correct that the resolution is low, 100 ns for a 10 MHz DUT with a 10 Hz frequency offset but the hetrodyne factor takes the theoretical resolution to 100 fs. That's not shabby for a very low cost DDMTD. And of course, the actual noise floor will not be close to this but potentially it's better than a 5370 and a lot easier to maintain. :o) Simon, I have a 4 channel 1 ns tagger working but I can't successfully link the FTDI library to a c program so doing this in hardware looks far more attractive to me. Here's how I see it at this point: -- Objective: --A four channel DDMTD with 44 bit time tags delivered over the USB port --At least 100 Hz beat frquency on each channel --The hardware is capable of much higher rates but increasing the beat frequency offset --degrades resolution and realistically the device will probably be used at 5 or 10 Hz -- -- Additional Hardware Required: --A wing with three or five LTC6957-1 low phase noise buffers to convert sine inputs into --high speed low-jitter square waves using LVPECL differential outputs --Either an oscillator offset by the beat frequency or a DDS frequency generator --A USB equipped computer -- --Architecture --Differential inputs are fed to the master clock, thence to the D flip-flops clocks --Differential inputs for each channel are fed to the data inputs for each flip-flop --The master clock drives a 44 bit counter which is common to all four channels --Each channel has two independent counters, provisionally 14 bit, designated high and low --The low counter first establishes a low state without transitions i.e. it times out --After the low counter times out, the flip-flop is armed --The first high output at q resets and starts both high and low counters - whichever counts depends on whether q is high or low --Every time the high and low counters match we store the 44 bit count; each new match replaces the previous one --At some point (2^14 highs) the high counter will roll over - hopefully low will have stopped counting much earlier --The highest stored match should meet the equal count criteria as described in the P. Moreira and I. Darwazeh paper --Since there are four channels it will be necessary to multiplex the time tags into the fifo --The multiplexer will add 1 bit per channel for one-hot channel id coding --The 48 bits will clock into a 48 bit to 8 bit fifo thence to an 8 bit USB port I believe you can have multiple points where the two counts match but I don't have any data to confirm that. I played with this in excel and when you feed it ones and zeros in a distribution that looks like the typical output out of a digital sampler it is possible to get multiple matches. My intention is to go with the last crossing and the scheme mentioned above does this rather trivially. Unless, of course, I'm missing something and I usually do. I've got a Pipistrello board and it has the option of an asynchronous fifo USB interface; since I've already paid my dues on that I'll just use that code again. The data rate is so low that snail mail would work. The computer gets a series of time tags and your program has to pair up the channels to get the deltas. Getting time tags lets you compare three or four devices simultaneously and facilitates three-cornered hat calculations. I suspect that's a lot easier to say than do but we'll cross that bridge if we ever get there. Also time tags permit continuous sampling; there's no counter dead-time which I think can be an issue when it causes variable data sampling rates. Bob Camp mention Collins low jitter hard limiters but I suspect that's much more of an issue on the very shallow slopes you see on 5 or 10 Hz mixer outputs. The LTC6957 is probably overkill on 10 MHz inputs but I believe they're a tad better than a 74AC gate, but then again maybe not all that much better. Lot more expensive. Bob C discussed sine to square conversion in a recent post (IIRC) perhaps in connection with 5V to 3.3V conversion, and for a low cost solution the 74AC gate looks pretty good and they're easy to dead bug. I'm out of spit. Later bob On 10/11/2014 9:17 PM, Bob Camp wrote: Hi Ok, a little more data: You can hook your flip flop up as a sampler or as a full blown mixer. Hooked up as a full blown mixer, you get the 20 MHz and 10 Hz signals. You also get more resolution on the 10 Hz. Either way, the 10 Hz is still a beat note. In the case of a sampler, the filter is there for edge jitter. With a sampler, your data is
Re: [time-nuts] Digital Mixing with a BeagleBone Black and D Flip Flop
Original thread on DDMTD in 2008: https://www.febo.com/pipermail/time-nuts/2008-December/034955.html Later comment on using a shift register to minimise metastability issues: https://www.febo.com/pipermail/time-nuts/2011-August/058648.html Bruce On Sunday, October 12, 2014 12:14:27 AM Robert Darby wrote: Bob Camp, Bob, Simon is talking about the sampler versus a true mixer. This is the idea I asked you about some months ago when I asked about how the digital filter functions. You were kind to explain the filter method in terms of buckets. You are of course correct that the resolution is low, 100 ns for a 10 MHz DUT with a 10 Hz frequency offset but the hetrodyne factor takes the theoretical resolution to 100 fs. That's not shabby for a very low cost DDMTD. And of course, the actual noise floor will not be close to this but potentially it's better than a 5370 and a lot easier to maintain. :o) Simon, I have a 4 channel 1 ns tagger working but I can't successfully link the FTDI library to a c program so doing this in hardware looks far more attractive to me. Here's how I see it at this point: -- Objective: --A four channel DDMTD with 44 bit time tags delivered over the USB port --At least 100 Hz beat frquency on each channel --The hardware is capable of much higher rates but increasing the beat frequency offset --degrades resolution and realistically the device will probably be used at 5 or 10 Hz -- -- Additional Hardware Required: --A wing with three or five LTC6957-1 low phase noise buffers to convert sine inputs into --high speed low-jitter square waves using LVPECL differential outputs --Either an oscillator offset by the beat frequency or a DDS frequency generator --A USB equipped computer -- --Architecture --Differential inputs are fed to the master clock, thence to the D flip-flops clocks --Differential inputs for each channel are fed to the data inputs for each flip-flop --The master clock drives a 44 bit counter which is common to all four channels --Each channel has two independent counters, provisionally 14 bit, designated high and low --The low counter first establishes a low state without transitions i.e. it times out --After the low counter times out, the flip-flop is armed --The first high output at q resets and starts both high and low counters - whichever counts depends on whether q is high or low --Every time the high and low counters match we store the 44 bit count; each new match replaces the previous one --At some point (2^14 highs) the high counter will roll over - hopefully low will have stopped counting much earlier --The highest stored match should meet the equal count criteria as described in the P. Moreira and I. Darwazeh paper --Since there are four channels it will be necessary to multiplex the time tags into the fifo --The multiplexer will add 1 bit per channel for one-hot channel id coding --The 48 bits will clock into a 48 bit to 8 bit fifo thence to an 8 bit USB port I believe you can have multiple points where the two counts match but I don't have any data to confirm that. I played with this in excel and when you feed it ones and zeros in a distribution that looks like the typical output out of a digital sampler it is possible to get multiple matches. My intention is to go with the last crossing and the scheme mentioned above does this rather trivially. Unless, of course, I'm missing something and I usually do. I've got a Pipistrello board and it has the option of an asynchronous fifo USB interface; since I've already paid my dues on that I'll just use that code again. The data rate is so low that snail mail would work. The computer gets a series of time tags and your program has to pair up the channels to get the deltas. Getting time tags lets you compare three or four devices simultaneously and facilitates three-cornered hat calculations. I suspect that's a lot easier to say than do but we'll cross that bridge if we ever get there. Also time tags permit continuous sampling; there's no counter dead-time which I think can be an issue when it causes variable data sampling rates. Bob Camp mention Collins low jitter hard limiters but I suspect that's much more of an issue on the very shallow slopes you see on 5 or 10 Hz mixer outputs. The LTC6957 is probably overkill on 10 MHz inputs but I believe they're a tad better than a 74AC gate, but then again maybe not all that much better. Lot more expensive. Bob C discussed sine to square conversion in a recent post (IIRC) perhaps in connection with 5V to 3.3V conversion, and for a low cost solution the 74AC gate looks pretty good and they're easy to dead bug. I'm out of spit. Later bob On 10/11/2014 9:17 PM, Bob Camp wrote: Hi Ok,
