Re: [time-nuts] LTE-Lite module
Hi Said, Thank you for taking the time to answer questions and provide info on the LTE unit to our group. I know we will not add much to your bottom line as we are a small group. We have come a long way with Thunderbolt without any help whatsoever with that company. Will be an interesting ride with your products! 73, Bill, WA2DVU Cape May, NJ -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Said Jackson via time-nuts Sent: Saturday, October 18, 2014 6:53 PM To: Bill Dailey Cc: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] LTE-Lite module Hi Bill, I think it makes perfect sense. But I have no idea how the units' loop stability would be with the 10811. That kind of testing is on the plate. You would preferably set the OCXO to a nominal tuning voltage of 1.5V using the mechanical adjustment, then let the LTE Lite do the rest. Please note that the LTE board will auto-sense the external ocxo frequency, so any of the boards would work. Please also note that due to the harmonic mixing issues I described earlier the best board to use for that setup would be the 19.2MHz version(!) or to remove the on-board tcxo altogether. Bye, Said Sent From iPhone On Oct 18, 2014, at 15:24, Bill Dailey docdai...@gmail.com wrote: Said, How tough would it be to mate the 10Mhz version up to a really good 10811? I have one that I acquired from Corby some time ago. I was going to spin my own but I wont realistically get to that with everything else I have going on. I was thinking of throwing the LTE-Lite and the 10811 in a box. I woudl then have a stock fury, An enhanced OEM fury (datum-c) and then this gadget with a 10-13 10811. Let me know if this doesnt make sense. I am an amateur. Bill On Sat, Oct 18, 2014 at 5:13 PM, S. Jackson via time-nuts time-nuts@febo.com wrote: Guys, one last email. The board will not fit into the Hammond enclosure without reworking the enclosure or removing the TCXO socket. We initially planned to ship the board without the socket, now all of them will have it. The board was designed to be used without the TCXO/Socket to fit into that enclosure. Caveat: please expect some rework to be necessary when using the suggested Hammond enclosure. bye, Said In a message dated 10/18/2014 12:56:06 Pacific Daylight Time, time-nuts@febo.com writes: Guys, we have been getting a good number of emails with questions that have already been addressed in the user manual or the FAQ, see the below link. We spent a lot of time putting the collateral together, may I please ask that you first look into these two documents to see if your question might already be addressed there? Paul, please search the LTE Lite user manual for Hammond and you will find it there: http://www.jackson-labs.com/index.php/products/lte_lite Thanks, Said _ Do you have a recommended Hammond chassis part number? -- Paul ___ 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. -- Doc Bill Dailey KXØO ___ 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. --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LTE-Lite module
Bill wrote: How tough would it be to mate the 10Mhz version up to a really good 10811? * * * I was thinking of throwing the LTE-Lite and the 10811 in a box. Unfortunately, to get the best out of the local oscillator, the control PLL must be carefully adjusted so that the oscillator itself controls the stability at averaging times (tau) where it is better than the GPS (generally, up to tau of several hundred to maybe several thousand seconds), and the GPS controls the stability at longer tau. The LTE-Lite has fixed (non-adjustable) loop parameters that cross over to the GPS at much lower tau than is appropriate for a good OCXO (but well suited to the installed TXCO). The other day Said (I think) mentioned some hacks that may sort-of improve the ability of an LTE-Lite to discipline an OCXO, but that's all they are -- very approximate hacks. There is really no way to properly mate an OCXO to the LTE-Lite control loop, which would require adjusting the PLL loop gain and the location of the loop's poles and zeroes (and possibly even adding new poles and zeroes). That would need to be done by changing the PLL parameters internal to the LTE-Lite, which are inaccessible. Without such reprogramming, the LTE-Light can never get the best out of an OCXO. Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LTE-Lite module
In message 20141019155055.osmik...@smtp11.mail.yandex.net, Charles Steinmetz writes: zeroes). That would need to be done by changing the PLL parameters internal to the LTE-Lite, which are inaccessible. Without such reprogramming, the LTE-Light can never get the best out of an OCXO. It certainly can and it's not even hard: Configure the LTE to emit a suitable frequency relative to the OCXO and use an analog PLL to steer the OCXO's EFC. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Where the 5370's are...
I have to agree, it sounds like either the remembrances of someone that was there in the 1950's, or a recitation of one of the A-Bomb book's descriptions of New Mexico during the Manhattan project. I drove to Los Alamos, New Mexico, from Maryland two summers ago, and it was nothing like the two posters described. It had real roads, and real phone numbers... 4 bars on the cell phone.. mostly... even in the Indian reservations. I had previously driven to New Mexico in 1970, and it was pretty much the same this time as it was the last time. The only substantive difference between the roads in NM, and the roads in the rest of the middle of the country was the color, and texture, of the scenery. They also had shopping centers, housing developments, very nice hotels near the casinos, and crime. Bubonic plague did show up in some wild animals (according to the TV news... yes, they have TV stations.), the summer I was there. They recommend against petting the wild animals... well Duh! UPS delivered several packages to my son in Los Alamos, and mail service worked both ways, so even that isn't a problem. They even have airports. I cannot imagine any interstate in the country being in the state you describe since Eisenhower's Defense Interstate Act of the 1950's/60's. -Chuck Harris (my only and last words on this off topic subject) Dave Brown wrote: Was there couple of weeks back to visit Los Alamos and the VLA- among other things- sure aint like that now. Gee you guys must be old.! BTW- the Black Hole is dead- no visible stock looking in windows and all closed up. DaveB, Christchurch, NZ - Original Message - From: Mark Sims hol...@hotmail.com To: time-nuts@febo.com Sent: Sunday, October 19, 2014 5:24 PM Subject: [time-nuts] Where the 5370's are... if New Mexico is really a legitimate US state. I dunno, I've been there. Was exposed to bubonic plague. And a friend caught some wonderful blue corn tortilla parasite. And the interstate highway was two narrow strips of asphalt (one for each pair of wheels) separated by a few feet of grass. And the phone numbers were four digits long. ___ 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] LTE-Lite module
Poul-Henning wrote: zeroes). That would need to be done by changing the PLL parameters internal to the LTE-Lite, which are inaccessible. Without such reprogramming, the LTE-Light can never get the best out of an OCXO. It certainly can and it's not even hard: Configure the LTE to emit a suitable frequency relative to the OCXO and use an analog PLL to steer the OCXO's EFC. Any worthwhile OCXO will need a loop with a time constant on the order of hundreds of seconds (a corner frequency on the order of uHz) to get the most out of it as a GPSDO. As has been discussed on the list many times, there is simply no practicable way to design an analog loop with such a long time constant. So the person designing the PLL must be able to design and build an all-digital PLL, or settle for a loop that crosses over to the GPS several decades too early (which is certainly not getting the most out of the OCXO). Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LTE-Lite module
In message 20141019183956.dt4ss...@smtp2o.mail.yandex.net, Charles Steinmetz writes: Configure the LTE to emit a suitable frequency relative to the OCXO and use an analog PLL to steer the OCXO's EFC. Then do it digital, it's not like it's rocket science... Take the analog phase detector output, read it with ADC pin, do loop in software, drive efc with DAC. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LTE-Lite module
Hi The phase comparison part of the PLL is pretty straightforward if you are looking at two RF frequencies. An XOR gate is one solution, there are many others. Getting something like 100 to 200 ns full scale on the phase comparator makes the rest of the gizmo much easier. A 12 bit ADC on a MCU will get you to 100’s of ps per bit., That is more resolution (it’s 1 ns) than you need for this. Controlling the OCXO is either an outboard ADC ($2 or so) or a PWM (free with the MCU). There will be a few regulators, resistors, caps, and maybe a pot or two involved as well. Total parts cost on the digital loop done with an appropriate MCU is probably less than $10. Custom code wise, it’s a few hundred lines of C on a 32 bit ARM. Pre built (wizard driven) device init stuff will be way more than that, but you don’t write any of that. Since it’s just a PLL and not a full GPSDO, there’s not a whole lot to it. If building up the MCU board is the issue, there are *many* eval boards out there for $15 that will do the trick. Debug, optimization and tweaking are where the major effort is (like 80 to 90%). That will take at least few months of work and require some test gear. Any time you plug in a significantly different oscillator, you will have to put in this part of the effort. Getting the long run ADEV data, making sure it’s right, and then analyzing the result is something there is no magic shortcut around. If you are set up for it (you are a TIme Nut right?) , there’s no cost other than your time. If it’s a hobby - your time is free (or is it …). No it’s not a “plug in a pre-made gizmo and forget about it” sort of thing. There is real work, lots of time, mental effort, working gear, and patience involved. You *will* get it wrong more often than you get it right as you go through the process. Stuff happens, runs crash, gear fails, it’s the real world. That’s the learning part of the project. If its a hobby that’s what you are doing this for. Bob On Oct 19, 2014, at 10:39 AM, Charles Steinmetz csteinm...@yandex.com wrote: Poul-Henning wrote: zeroes). That would need to be done by changing the PLL parameters internal to the LTE-Lite, which are inaccessible. Without such reprogramming, the LTE-Light can never get the best out of an OCXO. It certainly can and it's not even hard: Configure the LTE to emit a suitable frequency relative to the OCXO and use an analog PLL to steer the OCXO's EFC. Any worthwhile OCXO will need a loop with a time constant on the order of hundreds of seconds (a corner frequency on the order of uHz) to get the most out of it as a GPSDO. As has been discussed on the list many times, there is simply no practicable way to design an analog loop with such a long time constant. So the person designing the PLL must be able to design and build an all-digital PLL, or settle for a loop that crosses over to the GPS several decades too early (which is certainly not getting the most out of the OCXO). Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] locking oscillators - an increase in power and/or stability ?
The interesting discussions on this site provoked me to try the experiment with two, fairly identical, Gunn K-band oscillators operating at 24.125 GHz. Individual power outputs were +18.5 and +19.5 dBm or 0.071W and 0.089W, respectively. By adding E/H tuners between the oscillator and precision attenuator used to measure output power,output powers could be increased to 0.118W and 0.148W respectively, an increase of 2.2 dB in each case, and total power of 0.265W. Next the oscillators wee combined with a matched magic-T. A a Gunn oscillator, followed by E/H-tuner was connected to each end port. A termination was placed in the top (out of phase) port, The in-phase side port was connected to another E/H-tuner, followed by an HP K-382A precision calibrated attenuator, HP K-486A thermistor mount, and HP 432A power meter. Adjusting the three E/H tuners for maximum, a power output power of +24.25 or 0.266W was attained. Thus no power gain was observed by combining with the magic-T. In summary, the sum of the Gunn oscillator powers, operated individually without E/H tuners was 0.160W. Adding E/H-tuners increased their total output to 0.265W. When the oscillators were combined with a magic-T and three E/H-tuners, total power was 0.266W, virtually the same as the sum of individual power outputs. Adjustment of the E/H-tuners between oscillators and the magic-T was critical as the oscillators tended to drop out of oscillation near the maximum power adjustment settings. It appeared the tuners were resonating the output irises of the oscillators so as to circumvent their isolation function and drain more power from the cavities. This was discussed in an earlier message from John C Roos, K6IQL. Conclusion: Gunn oscillators are necessarily very inefficient devices. Their stable operation depends on an output iris to limit output power so as to achieve a balance that provides for stable operation. The designer's intentions can be overcome by resonating the output iris so as to overcome the limitation and increase power and efficiency at the expense of stability. Bruce, KG6OJI ___ 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] LTE-Lite module
Hi On Oct 19, 2014, at 3:35 PM, Charles Steinmetz csteinm...@yandex.com wrote: Bob wrote (alluding also to something Poul-Henning wrote): The phase comparison part of the PLL is pretty straightforward if you are looking at two RF frequencies. An XOR gate is one solution, there are many others. Getting something like 100 to 200 ns full scale on the phase comparator makes the rest of the gizmo much easier. All true. However... A 12 bit ADC on a MCU will get you to 100's of ps per bit. That is more resolution (it's 1 ns) than you need for this. Getting an ADC to sample fast and accurately enough to provide that honest resolution is not trivial. And if you have that, you'll almost certainly have the resources to do the phase comparator digitally, too, which brings many advantages -- so I see no reason to use an analog PC. If you take a look at some of the newer ARM MCU’s they are getting 13+ solid bits out of their ADC’s at a 10 KHz rate. That’s more than good enough for anything you are trying to do with this design. There’s no need to make it any more complex. A single gate XOR plus the eval board is just a about all you need. One dead bug part on the eval board and the assembly process is pretty much done. Maybe 45 minutes of work if you need to go find all the bits and pieces around your bench. Since almost nothing in the design is running at high speed, layout issues should not be a big deal. You could also do it on a fragment of board like the divider from earlier in this thread. Custom code wise, it's a few hundred lines of C on a 32 bit ARM. Pre built (wizard driven) device init stuff will be way more than that, but you don't write any of that. A proper digital filter that computes a new running value at least every second will be more complex than that, but you're right, it's not an unfathomable task. Then comes the real work, well summarized by Bob: Debug, optimization and tweaking are where the major effort is (like 80 to 90%). That will take at least few months of work and require some test gear. Any time you plug in a significantly different oscillator, you will have to put in this part of the effort. Getting the long run ADEV data, making sure it's right, and then analyzing the result is something there is no magic shortcut around. * * * No it's not a plug in a pre-made gizmo and forget about it sort of thing. There is real work, lots of time, mental effort, working gear, and patience involved. You *will* get it wrong more often than you get it right as you go through the process. All of this explains why the woods are not full of state-of-the-art GPSDO controllers just waiting for people to couple them with whatever OCXO they bought on ebay. The optimization process is at least 90% perspiration and preparation. Neither of those are outside the range of what an average Joe can handle. The other (at most) 10% is very much a “that depends” sort of thing. You can head down all sorts of rabbit holes as you dig into this or that. For that, the list archives have tons of information to work from. There is *way* more in a GPSDO than what we are talking about here. TimeNuts may or may not care much about that extra stuff, but it’s in there. BTW, I mean no slight to the LTE-Light. Judging from the JL products I've used, I expect that it is a fine product well-designed for its task. But that task is controlling a TCXO, not controlling an OCXO that is stable to 10e-12 or better at tau from 1 to 100 seconds (unless one goes to the trouble described above). For a general look at the magnitude of the stability difference between a TCXO and a number of OCXOs and other frequency standards, see attached (if the pic doesn't make it through the listserv, see http://leapsecond.com/museum/manyadev.gif). Best regards, Charles Oscillator_comparison_tvb.jpg___ 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. The idea is not to make it as complex as you possibly could, but to make it as simple as possible and still have it work fine. There are a lot of shortcuts you can take with a one off unit that a commercial design would never use. 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.
Re: [time-nuts] LTE-Lite module
With all the work around if you want very good performance use a Shera. We have super results with a Morion, Shera and ublox M7 Bert Kehren In a message dated 10/19/2014 4:08:32 P.M. Eastern Daylight Time, kb...@n1k.org writes: Hi On Oct 19, 2014, at 3:35 PM, Charles Steinmetz csteinm...@yandex.com wrote: Bob wrote (alluding also to something Poul-Henning wrote): The phase comparison part of the PLL is pretty straightforward if you are looking at two RF frequencies. An XOR gate is one solution, there are many others. Getting something like 100 to 200 ns full scale on the phase comparator makes the rest of the gizmo much easier. All true. However... A 12 bit ADC on a MCU will get you to 100's of ps per bit. That is more resolution (it's 1 ns) than you need for this. Getting an ADC to sample fast and accurately enough to provide that honest resolution is not trivial. And if you have that, you'll almost certainly have the resources to do the phase comparator digitally, too, which brings many advantages -- so I see no reason to use an analog PC. If you take a look at some of the newer ARM MCU’s they are getting 13+ solid bits out of their ADC’s at a 10 KHz rate. That’s more than good enough for anything you are trying to do with this design. There’s no need to make it any more complex. A single gate XOR plus the eval board is just a about all you need. One dead bug part on the eval board and the assembly process is pretty much done. Maybe 45 minutes of work if you need to go find all the bits and pieces around your bench. Since almost nothing in the design is running at high speed, layout issues should not be a big deal. You could also do it on a fragment of board like the divider from earlier in this thread. Custom code wise, it's a few hundred lines of C on a 32 bit ARM. Pre built (wizard driven) device init stuff will be way more than that, but you don't write any of that. A proper digital filter that computes a new running value at least every second will be more complex than that, but you're right, it's not an unfathomable task. Then comes the real work, well summarized by Bob: Debug, optimization and tweaking are where the major effort is (like 80 to 90%). That will take at least few months of work and require some test gear. Any time you plug in a significantly different oscillator, you will have to put in this part of the effort. Getting the long run ADEV data, making sure it's right, and then analyzing the result is something there is no magic shortcut around. * * * No it's not a plug in a pre-made gizmo and forget about it sort of thing. There is real work, lots of time, mental effort, working gear, and patience involved. You *will* get it wrong more often than you get it right as you go through the process. All of this explains why the woods are not full of state-of-the-art GPSDO controllers just waiting for people to couple them with whatever OCXO they bought on ebay. The optimization process is at least 90% perspiration and preparation. Neither of those are outside the range of what an average Joe can handle. The other (at most) 10% is very much a “that depends” sort of thing. You can head down all sorts of rabbit holes as you dig into this or that. For that, the list archives have tons of information to work from. There is *way* more in a GPSDO than what we are talking about here. TimeNuts may or may not care much about that extra stuff, but it’s in there. BTW, I mean no slight to the LTE-Light. Judging from the JL products I've used, I expect that it is a fine product well-designed for its task. But that task is controlling a TCXO, not controlling an OCXO that is stable to 10e-12 or better at tau from 1 to 100 seconds (unless one goes to the trouble described above). For a general look at the magnitude of the stability difference between a TCXO and a number of OCXOs and other frequency standards, see attached (if the pic doesn't make it through the listserv, see http://leapsecond.com/museum/manyadev.gif). Best regards, Charles Oscillator_comparison_tvb.jpg___ 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. The idea is not to make it as complex as you possibly could, but to make it as simple as possible and still have it work fine. There are a lot of shortcuts you can take with a one off unit that a commercial design would never use. 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
Re: [time-nuts] LTE-Lite module
Bob wrote (alluding also to something Poul-Henning wrote): The phase comparison part of the PLL is pretty straightforward if you are looking at two RF frequencies. An XOR gate is one solution, there are many others. Getting something like 100 to 200 ns full scale on the phase comparator makes the rest of the gizmo much easier. All true. However... A 12 bit ADC on a MCU will get you to 100's of ps per bit. That is more resolution (it's 1 ns) than you need for this. Getting an ADC to sample fast and accurately enough to provide that honest resolution is not trivial. And if you have that, you'll almost certainly have the resources to do the phase comparator digitally, too, which brings many advantages -- so I see no reason to use an analog PC. Custom code wise, it's a few hundred lines of C on a 32 bit ARM. Pre built (wizard driven) device init stuff will be way more than that, but you don't write any of that. A proper digital filter that computes a new running value at least every second will be more complex than that, but you're right, it's not an unfathomable task. Then comes the real work, well summarized by Bob: Debug, optimization and tweaking are where the major effort is (like 80 to 90%). That will take at least few months of work and require some test gear. Any time you plug in a significantly different oscillator, you will have to put in this part of the effort. Getting the long run ADEV data, making sure it's right, and then analyzing the result is something there is no magic shortcut around. * * * No it's not a plug in a pre-made gizmo and forget about it sort of thing. There is real work, lots of time, mental effort, working gear, and patience involved. You *will* get it wrong more often than you get it right as you go through the process. All of this explains why the woods are not full of state-of-the-art GPSDO controllers just waiting for people to couple them with whatever OCXO they bought on ebay. BTW, I mean no slight to the LTE-Light. Judging from the JL products I've used, I expect that it is a fine product well-designed for its task. But that task is controlling a TCXO, not controlling an OCXO that is stable to 10e-12 or better at tau from 1 to 100 seconds (unless one goes to the trouble described above). For a general look at the magnitude of the stability difference between a TCXO and a number of OCXOs and other frequency standards, see attached (if the pic doesn't make it through the listserv, see http://leapsecond.com/museum/manyadev.gif). Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LTE-Lite module
On 10/19/14, 1:08 PM, Bob Camp wrote: Hi On Oct 19, 2014, at 3:35 PM, Charles Steinmetz csteinm...@yandex.com wrote: Bob wrote (alluding also to something Poul-Henning wrote): The phase comparison part of the PLL is pretty straightforward if you are looking at two RF frequencies. An XOR gate is one solution, there are many others. Getting something like 100 to 200 ns full scale on the phase comparator makes the rest of the gizmo much easier. All true. However... A 12 bit ADC on a MCU will get you to 100's of ps per bit. That is more resolution (it's 1 ns) than you need for this. Getting an ADC to sample fast and accurately enough to provide that honest resolution is not trivial. And if you have that, you'll almost certainly have the resources to do the phase comparator digitally, too, which brings many advantages -- so I see no reason to use an analog PC. If you take a look at some of the newer ARM MCU’s they are getting 13+ solid bits out of their ADC’s at a 10 KHz rate. That’s more than good enough for anything you are trying to do with this design. There’s no need to make it any more complex. I'm using the Freescale Kinetix K20 parts, which have 16 bit differential input ADCs, and built in averaging. The raw ADC can sample at about 400kHz. You can easily get 14 bit performance from these at tens of kHz rates. I need I/Q, so I sample two inputs at 50 kHz (read one, then the other) without averaging (so they're about 2.5 microseconds apart), and then decimate them through a 2 stage CIC and a 13 tap FIR filter down to 200 Hz. This takes about 60% of the processor running at 48MHz. ___ 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] LTE-Lite module
Hi On Oct 19, 2014, at 5:00 PM, Jim Lux jim...@earthlink.net wrote: On 10/19/14, 1:08 PM, Bob Camp wrote: Hi On Oct 19, 2014, at 3:35 PM, Charles Steinmetz csteinm...@yandex.com wrote: Bob wrote (alluding also to something Poul-Henning wrote): The phase comparison part of the PLL is pretty straightforward if you are looking at two RF frequencies. An XOR gate is one solution, there are many others. Getting something like 100 to 200 ns full scale on the phase comparator makes the rest of the gizmo much easier. All true. However... A 12 bit ADC on a MCU will get you to 100's of ps per bit. That is more resolution (it's 1 ns) than you need for this. Getting an ADC to sample fast and accurately enough to provide that honest resolution is not trivial. And if you have that, you'll almost certainly have the resources to do the phase comparator digitally, too, which brings many advantages -- so I see no reason to use an analog PC. If you take a look at some of the newer ARM MCU’s they are getting 13+ solid bits out of their ADC’s at a 10 KHz rate. That’s more than good enough for anything you are trying to do with this design. There’s no need to make it any more complex. I'm using the Freescale Kinetix K20 parts, which have 16 bit differential input ADCs, and built in averaging. The raw ADC can sample at about 400kHz. You can easily get 14 bit performance from these at tens of kHz rates. I need I/Q, so I sample two inputs at 50 kHz (read one, then the other) without averaging (so they're about 2.5 microseconds apart), and then decimate them through a 2 stage CIC and a 13 tap FIR filter down to 200 Hz. This takes about 60% of the processor running at 48MHz. I’m using parts from the same family, but not doing the whole DDS thing. Single input and control loop - the part sleeps about 98% of the time. The demo boards (Freedom boards) are all below $15 and free if you go to one of their (often free) classes. Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LTE-Lite module
At the low end of the spectrum, I tried to make the simplest possible GPSDO what would still work. Assuming you have a GPS with 1PPS output, an OCXO and a small DC power supply I was able to get the entire parts for the controller, board, hookup wire and all for under $5. I purposely took the lowest cost solution at each decision point just to see what you'd end up with. Part were from eBay. The result is not bad. but I don't have a really good way to test it. I'm using a Thunderbolt for the 1PPS and a pretty decent OXCO part. Why build a low-end GPSDO when yo have a Thunderbolt? It's and experiment. The way I test is to place the sine output from the TB and from my GPSDO both on a dual channel scope and adjust it so the two sine waves are superimposed. Then I wait for them not to be superimposed. What I see is that over 1/2 hour or so they get slightly out of phase but then drift back in phase, This happens cyclically. It is because of the VERY simply controller. I tried to minimize lines of C++ code. It's running about 16 lines of code, more or less. Using my counter I think the GPSDO is good to 1E-10. Rather than using a $15 ARM MCU board I used a $3 AVR board and used 100% 16-bit integer math in a very simple control loop. There is one external chip because the little AVR could not deal with the 10MHz signal from the OCXO so I used a divider chip. I use two 8-bit DACs to control the EFC on the OCXO. One is curse adjustment, one fine. Added with a resister network and an RC filter with almost a 1 second time constant. If you can spend $35 you can build a very sophisticated controller that logs internal diagnostic data to a computer over USB and displays it's internal status on a graphic LCD panel. Well, actually my controller has an LCD status display and logs data to a PC. But with those parts plugged in the cost is closer to $10. On Sun, Oct 19, 2014 at 2:13 PM, Bob Camp kb...@n1k.org wrote: Hi On Oct 19, 2014, at 5:00 PM, Jim Lux jim...@earthlink.net wrote: On 10/19/14, 1:08 PM, Bob Camp wrote: Hi On Oct 19, 2014, at 3:35 PM, Charles Steinmetz csteinm...@yandex.com wrote: Bob wrote (alluding also to something Poul-Henning wrote): The phase comparison part of the PLL is pretty straightforward if you are looking at two RF frequencies. An XOR gate is one solution, there are many others. Getting something like 100 to 200 ns full scale on the phase comparator makes the rest of the gizmo much easier. All true. However... A 12 bit ADC on a MCU will get you to 100's of ps per bit. That is more resolution (it's 1 ns) than you need for this. Getting an ADC to sample fast and accurately enough to provide that honest resolution is not trivial. And if you have that, you'll almost certainly have the resources to do the phase comparator digitally, too, which brings many advantages -- so I see no reason to use an analog PC. If you take a look at some of the newer ARM MCU’s they are getting 13+ solid bits out of their ADC’s at a 10 KHz rate. That’s more than good enough for anything you are trying to do with this design. There’s no need to make it any more complex. I'm using the Freescale Kinetix K20 parts, which have 16 bit differential input ADCs, and built in averaging. The raw ADC can sample at about 400kHz. You can easily get 14 bit performance from these at tens of kHz rates. I need I/Q, so I sample two inputs at 50 kHz (read one, then the other) without averaging (so they're about 2.5 microseconds apart), and then decimate them through a 2 stage CIC and a 13 tap FIR filter down to 200 Hz. This takes about 60% of the processor running at 48MHz. I’m using parts from the same family, but not doing the whole DDS thing. Single input and control loop - the part sleeps about 98% of the time. The demo boards (Freedom boards) are all below $15 and free if you go to one of their (often free) classes. 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. -- 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] LTE-Lite module
We did the same using a 1 KHz out of the $ 14 ubolx M7 and a Morion . Results better than 1 E-10. Some time nuts are now assembling and testing the same. Total cost less than $ 10 not counting OCXO or GPS. Most expensive item is the filter capacitor. Bert Kehren In a message dated 10/19/2014 6:15:06 P.M. Eastern Daylight Time, albertson.ch...@gmail.com writes: At the low end of the spectrum, I tried to make the simplest possible GPSDO what would still work. Assuming you have a GPS with 1PPS output, an OCXO and a small DC power supply I was able to get the entire parts for the controller, board, hookup wire and all for under $5. I purposely took the lowest cost solution at each decision point just to see what you'd end up with. Part were from eBay. The result is not bad. but I don't have a really good way to test it. I'm using a Thunderbolt for the 1PPS and a pretty decent OXCO part. Why build a low-end GPSDO when yo have a Thunderbolt? It's and experiment. The way I test is to place the sine output from the TB and from my GPSDO both on a dual channel scope and adjust it so the two sine waves are superimposed.Then I wait for them not to be superimposed. What I see is that over 1/2 hour or so they get slightly out of phase but then drift back in phase, This happens cyclically. It is because of the VERY simply controller. I tried to minimize lines of C++ code. It's running about 16 lines of code, more or less. Using my counter I think the GPSDO is good to 1E-10. Rather than using a $15 ARM MCU board I used a $3 AVR board and used 100% 16-bit integer math in a very simple control loop. There is one external chip because the little AVR could not deal with the 10MHz signal from the OCXO so I used a divider chip. I use two 8-bit DACs to control the EFC on the OCXO. One is curse adjustment, one fine. Added with a resister network and an RC filter with almost a 1 second time constant. If you can spend $35 you can build a very sophisticated controller that logs internal diagnostic data to a computer over USB and displays it's internal status on a graphic LCD panel. Well, actually my controller has an LCD status display and logs data to a PC. But with those parts plugged in the cost is closer to $10. On Sun, Oct 19, 2014 at 2:13 PM, Bob Camp kb...@n1k.org wrote: Hi On Oct 19, 2014, at 5:00 PM, Jim Lux jim...@earthlink.net wrote: On 10/19/14, 1:08 PM, Bob Camp wrote: Hi On Oct 19, 2014, at 3:35 PM, Charles Steinmetz csteinm...@yandex.com wrote: Bob wrote (alluding also to something Poul-Henning wrote): The phase comparison part of the PLL is pretty straightforward if you are looking at two RF frequencies. An XOR gate is one solution, there are many others. Getting something like 100 to 200 ns full scale on the phase comparator makes the rest of the gizmo much easier. All true. However... A 12 bit ADC on a MCU will get you to 100's of ps per bit. That is more resolution (it's 1 ns) than you need for this. Getting an ADC to sample fast and accurately enough to provide that honest resolution is not trivial. And if you have that, you'll almost certainly have the resources to do the phase comparator digitally, too, which brings many advantages -- so I see no reason to use an analog PC. If you take a look at some of the newer ARM MCU’s they are getting 13+ solid bits out of their ADC’s at a 10 KHz rate. That’s more than good enough for anything you are trying to do with this design. There’s no need to make it any more complex. I'm using the Freescale Kinetix K20 parts, which have 16 bit differential input ADCs, and built in averaging. The raw ADC can sample at about 400kHz. You can easily get 14 bit performance from these at tens of kHz rates. I need I/Q, so I sample two inputs at 50 kHz (read one, then the other) without averaging (so they're about 2.5 microseconds apart), and then decimate them through a 2 stage CIC and a 13 tap FIR filter down to 200 Hz. This takes about 60% of the processor running at 48MHz. I’m using parts from the same family, but not doing the whole DDS thing. Single input and control loop - the part sleeps about 98% of the time. The demo boards (Freedom boards) are all below $15 and free if you go to one of their (often free) classes. 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. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
[time-nuts] 5370B stop port has died
My Stop port has just stopped working. The light is on all the time. I installed the Beaglebone CPU a few months back. Is there a chance it could be a software issue causing it? (I will re-install the original CPU to test - but I was wondering if anyone else had a similar problem.) 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.
Re: [time-nuts] LTE-Lite module
Hi We seem to have swung from “it’s impossible, don’t even try” to “it’s trivial, you should have it done in a few minutes” :) (Yes I know that’s *not* at all what was said in either case. We have swung a ways though) Yes, I can do it for less than $1 in parts. That’s not to say it’s the *right* way to do it. Yes, I can have it “done (locked up) in a few hours (from scratch, including the parts). That’s not to say you *should* do it that way. My way most certainly should not be your way. The stuff I have sitting around is not the stuff you have lying around. What I paid may not be what you pay. We spend a lot of time playing “I can do it cheaper”. Unless a few months of your time *really* is worth $10, the “cheaper” part simply does not count past some point. The cost of even one meal out over several months will wipe out that advantage. Doing it with a part that is running a 10 bit ADC that really gives you 8 bit performance will indeed impact the result. It’s cheaper, but how much struggle will there be to make it work well? Will it add a month or three to the project? Will you start over from scratch? Who knows. Are we comparing a board anybody can get for $15 to just the cpu on another board .. maybe we are. If what counts is a price that somebody got once, I have boards that I got for free. Do they count as $0 in a project? There’s really no value even going down that road. Each time this comes up on the list, we typically spend a month with everybody tossing up their favorite board. We each post several messages talking about the great deal we got. We never seem to get around to actually doing much with those cheap boards compared to the time everybody spends extolling their virtues (and ignoring their drawbacks). A $50 board is no different than a $1 board in this case. They both have near zero impact on the total investment in the project. If they did / do - buy a $135 OCXO based GPSDO rather than the $185 LTE board. That puts you $50 and months of your time ahead. If you want to start from scratch and get a result that is “OCXO” caliber, it will take a while. 1x10^-10 is not your target. The LTE part pretty much does that. Your target is at least 1x10^-11 short term and much better a you go to a few hundred seconds. In order to say you have hit it, you need to test it and verify that you have hit it. No I can’t do a run that takes a month to verify a part I build in a short time.Nobody can do that, it takes time. No I don’t have a gizmo that’ stable to 1x10^-13 over a month sitting in the basement. If I already had that, why would I need to put an OCXO on a LTE board? I have to do some work simply to do the test (like build several and cross check them). How much time does the testing take? You want something around 100 samples for a good ADEV number. You need data out to 1,000 seconds (and more likely 10,000 seconds) to check the loop out. Each run will be in the 1 to 10 days range. Once you have it “right” you really need to check it over a month or two to watch for GPS “once a day” issues. If you have a really good setup, you will get good data 4 runs out of 5. With a basement setup, that may drop to 2 in 5. The job is not done once the first one is locked. That’s the quick and easy part. The full job is only done once you have it optimized and know you have done so from measured data. That’s true if you are making one, or making a few hundred thousand of them. Bob On Oct 19, 2014, at 6:14 PM, Chris Albertson albertson.ch...@gmail.com wrote: At the low end of the spectrum, I tried to make the simplest possible GPSDO what would still work. Assuming you have a GPS with 1PPS output, an OCXO and a small DC power supply I was able to get the entire parts for the controller, board, hookup wire and all for under $5. I purposely took the lowest cost solution at each decision point just to see what you'd end up with. Part were from eBay. The result is not bad. but I don't have a really good way to test it. I'm using a Thunderbolt for the 1PPS and a pretty decent OXCO part. Why build a low-end GPSDO when yo have a Thunderbolt? It's and experiment. The way I test is to place the sine output from the TB and from my GPSDO both on a dual channel scope and adjust it so the two sine waves are superimposed. Then I wait for them not to be superimposed. What I see is that over 1/2 hour or so they get slightly out of phase but then drift back in phase, This happens cyclically. It is because of the VERY simply controller. I tried to minimize lines of C++ code. It's running about 16 lines of code, more or less. Using my counter I think the GPSDO is good to 1E-10. Rather than using a $15 ARM MCU board I used a $3 AVR board and used 100% 16-bit integer math in a very simple control loop. There is one external chip because the little AVR could not deal with the 10MHz signal from the OCXO so I used a
Re: [time-nuts] 5370B stop port has died
Hi One of the classic ways to kill most of the 53xx boxes is to put a DC voltage on the input with the attenuator set to zero. 5335’s very much did not like a 5V level on the input. I spent more money replacing front end boards than I did on the counters when we bought them. I never looked to see if the 5370 shared that “feature” or not. I also never tried overloading mine. Bob On Oct 19, 2014, at 8:49 PM, Jim Palfreyman jim77...@gmail.com wrote: My Stop port has just stopped working. The light is on all the time. I installed the Beaglebone CPU a few months back. Is there a chance it could be a software issue causing it? (I will re-install the original CPU to test - but I was wondering if anyone else had a similar problem.) 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.
[time-nuts] GPS once a day issues ?
Hi Bob Camp, In your response to Chris, you said: Once you have it “right” you really need to check it over a month or two to watch for GPS “once a day” issues. Could I ask you what you meant by these once a day issues? Was this a general comment, or was it about something specific? As you know I'm working on a GPSDO and am doing a lot of testing, so if there's something else I should be looking for, please let me know. Bob - AE6RV ___ 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 once a day issues ?
Hi Bob, This multiple antenna issue is one I've been wanting to ask about, as well. I've got a GPS Source MS14 splitter (right place at the right time) so I don't specifically use multiple antennas. But, I've got the one still in the attic (disconnected) and the current one I put on the eave on the south side of the house. Those are both $5 powered pucks from ebay. I've also got a couple of Adafruits with the built-in antenna laying around. Do I really need to worry about the interaction of those antennas? I didn't get a feel for the spacing of interaction from previous posts on the subject. They're all at least 10 ft away from each other. FWIW, I only have one receiver hooked up to the splitter at the moment, and I do not have any terminators on the SMA ports as I don't think they're needed. The splitter has its own power supply. I'm only using the ports that are DC isolated from the antenna. Bob From: Bob Camp kb...@n1k.org To: Bob Stewart b...@evoria.net Sent: Sunday, October 19, 2014 9:01 PM Subject: Re: [time-nuts] GPS once a day issues ? Hi One of the reasons you want to wide space antennas if you are putting up more than one it a *hope* that worst case on one will not be identical to worst case on the other. The other way you can catch the problem is to simply look at what you loop is doing. If it does exactly the same “bump” every night at about 3AM….. Bob On Oct 19, 2014, at 9:58 PM, Bob Stewart b...@evoria.net wrote: Hi Bob, OK, it sounds like something that would not be clearly noticeable with the equipment I have. I haven't run many multi-day tests, so that's another handicap on this end. Still developing and testing, but things are looking better than the last time I spoke about my unit. thanks, Bob From: Bob Camp kb...@n1k.org To: Bob Stewart b...@evoria.net; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, October 19, 2014 8:50 PM Subject: Re: [time-nuts] GPS once a day issues ? Hi The GPS constellation repeats roughly once a day. It is not at all uncommon to have a “worst case” sattelite geometry for a given antenna location. If you have one, it will repeat once a day and show up as a bump in the timing out of your GPS module. If you track long term data, it will / may / can keep you from getting to the sort of stability you would expect in the 100,000 second range. It’s one of the main reasons that things like GPSD-Rb’s lock up with time constants much longer than 100K seconds. Yes having a Cs or something similar helps a lot looking for this sort of thing. Bob On Oct 19, 2014, at 9:26 PM, Bob Stewart b...@evoria.net wrote: Hi Bob Camp, In your response to Chris, you said: Once you have it “right” you really need to check it over a month or two to watch for GPS “once a day” issues. Could I ask you what you meant by these once a day issues? Was this a general comment, or was it about something specific? As you know I'm working on a GPSDO and am doing a lot of testing, so if there's something else I should be looking for, please let me know. Bob - AE6RV ___ 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 once a day issues ?
Hi Bob, (Yahoo let me down again and I responded only to you. Here is my reply again.) OK, it sounds like something that would not be clearly noticeable with the equipment I have. I haven't run many multi-day tests, so that's another handicap on this end. Still developing and testing, but things are looking better than the last time I spoke about my unit. thanks, Bob From: Bob Camp kb...@n1k.org To: Bob Stewart b...@evoria.net; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, October 19, 2014 8:50 PM Subject: Re: [time-nuts] GPS once a day issues ? Hi The GPS constellation repeats roughly once a day. It is not at all uncommon to have a “worst case” sattelite geometry for a given antenna location. If you have one, it will repeat once a day and show up as a bump in the timing out of your GPS module. If you track long term data, it will / may / can keep you from getting to the sort of stability you would expect in the 100,000 second range. It’s one of the main reasons that things like GPSD-Rb’s lock up with time constants much longer than 100K seconds. Yes having a Cs or something similar helps a lot looking for this sort of thing. Bob On Oct 19, 2014, at 9:26 PM, Bob Stewart b...@evoria.net wrote: Hi Bob Camp, In your response to Chris, you said: Once you have it “right” you really need to check it over a month or two to watch for GPS “once a day” issues. Could I ask you what you meant by these once a day issues? Was this a general comment, or was it about something specific? As you know I'm working on a GPSDO and am doing a lot of testing, so if there's something else I should be looking for, please let me know. Bob - AE6RV ___ 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 once a day issues ?
Hi The GPS constellation repeats roughly once a day. It is not at all uncommon to have a “worst case” sattelite geometry for a given antenna location. If you have one, it will repeat once a day and show up as a bump in the timing out of your GPS module. If you track long term data, it will / may / can keep you from getting to the sort of stability you would expect in the 100,000 second range. It’s one of the main reasons that things like GPSD-Rb’s lock up with time constants much longer than 100K seconds. Yes having a Cs or something similar helps a lot looking for this sort of thing. Bob On Oct 19, 2014, at 9:26 PM, Bob Stewart b...@evoria.net wrote: Hi Bob Camp, In your response to Chris, you said: Once you have it “right” you really need to check it over a month or two to watch for GPS “once a day” issues. Could I ask you what you meant by these once a day issues? Was this a general comment, or was it about something specific? As you know I'm working on a GPSDO and am doing a lot of testing, so if there's something else I should be looking for, please let me know. Bob - AE6RV ___ 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] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A, Z3811A, Z3812A GPSDO system
Fellow time-nuts, This (long) post is a review of the HP/Symmetricom Z3810A (or Z3810AS) GPSDO system built for Lucent circa 2000. I wrote it because I looked for more information before I bought one, and couldn't find much. It's relevant because (as of this writing), you can buy a full system on the usual auction site for about $150 plus shipping. For those of you lamenting the dearth of cheap Thunderbolts, this looks like one of the best deals going. The description of these objects does not include GPSDO, so time-nuts may have missed it. Search for one of the part numbers in the subject line and you should find it. So what is it? It's a dual GPSDO built by HP as a reference (Redundant Frequency and Time Generator, or RFTG) for a Lucent cell-phone base station, built to Lucent's spec KS-24361. Internally, it's a close cousin of a later-model Z3805A. Externally, it looks to be almost a drop-in replacement for the earlier RFTG system built to Lucent's spec KS-24019. That was a redundant system containing one rubidium (LPRO, in the one I have) and one OCXO in two almost-identical boxes. That spec went through several revisions with slightly different nameplates and presumably slightly different internals. You can generally find one or two examples on the auction site (search for RFTG or KS-24019). This system is similar, but the two boxes each contain a Milliren (MTI) 260-0624-C 5.000MHz DOCXO, and neither contains a rubidium. The Milliren DOXCO is the same one used in the later models of the HP Z3805A / 58503A. It's a very high-performance DOCXO, in the same class as the legendary HP 10811, and better than the one in most surplus Thunderbolts. The 5 MHz output is multiplied up to 10 MHz in at least one unit, and 15 MHz in both units. I don't have the ability to measure phase noise on these outputs, but I'd be interested to see the results if someone could. Nomenclature: The Z3810AS (there always seems to be an S at the end) is a system consisting of the Z3811A (the unit containing a GPS receiver), the Z3812A (the unit with no GPS receiver), and the Z3809A (a stupid little interconnect cable). The GPS receiver inside the Z3811A is a Motorola device, presumably some version of an OnCore. Where the Z3811A has a TNC GPS antenna input, the Z3812A has an SMA connector labeled 10MHz TP. That is indeed a 10 MHz output. It comes active as soon as power is applied to the unit, and its frequency follows the warmup curve of the OCXO. The two units have identical PCBs (stuffed slightly differently), and I have no doubt that someone can figure out how to add a 10 MHz output to the Z3811A as well. Operation: From the outside, these units are broadly similar to earlier units in the Lucent RFTG series. The (extremely valuable) website run by Didier, KO4BB, has a lot of information on those earlier units, much of which still applies here. The purpose of these units was to provide a reliable source of frequency and timing information to the cell-site electronics. The 15 MHz outputs from both units were connected to a power combiner/splitter and directed to various parts of the transmitter. The units negotiate with each other so that only one 15 MHz output is active at a time. The outputs labeled RS422/1PPS contained a 4800 baud (?) serial time code as well as the PPS signal, which were sent to the control computer. Power is applied to the connector labeled +24VDC and P1, in exactly the same way as the earlier RFTG units. Apply +24V to pin 1 and the other side of the power supply (GND or RTN) to pin 2. In these units, that power supply goes directly to an isolated Lucent DC/DC converter brick labeled IN: DC 18-36, 1.9A. Presumably you can run both units with a 4-amp supply. Once you have applied power, connect the Z3809A cable between the jacks labeled INTERFACE J5 on each unit. The earlier RFTG units used a special cable between two DE-9 connectors, and it mattered which end of the cable connected to which unit. The interconnect for these units is a high-density DE-15 connector (like a VGA plug). The Z3809A cable is so short that the two units need to be stacked one above the other, or the cable won't reach. It doesn't seem to matter which end of the cable goes to which unit. I don't know whether it's a straight-through cable, or whether you could use a VGA cable as a substitute. When you apply power, all the LEDs on the front panel will flash. The NO GPS light will continue flashing until you connect a GPS antenna. Once it sees a satellite, the light will stop flashing and remain on. The unit will conduct a self-survey for several hours. Eventually, if all is well, the Z3812A (REF 0 on its front panel) will show one green ON light and the Z3811A (REF 1) will show one yellow STBY light. This means that the Z3812A is actually transmitting its 15MHz output, and the other one is silently waiting to take over if it fails. Most time-nuts want to see more than a pretty green light. The
Re: [time-nuts] 5370B stop port has died
The last thing I had connected was the 1PPS output from a 5065A rubidium. I had the 5370B on 1 Megohm (I never use the internal 50 Ohm termination because of the risk of damage) so I assumed it would be fine. I've done this heaps of times before too. Jim Palfreyman On 20 October 2014 12:10, Bob Camp kb...@n1k.org wrote: Hi One of the classic ways to kill most of the 53xx boxes is to put a DC voltage on the input with the attenuator set to zero. 5335’s very much did not like a 5V level on the input. I spent more money replacing front end boards than I did on the counters when we bought them. I never looked to see if the 5370 shared that “feature” or not. I also never tried overloading mine. Bob On Oct 19, 2014, at 8:49 PM, Jim Palfreyman jim77...@gmail.com wrote: My Stop port has just stopped working. The light is on all the time. I installed the Beaglebone CPU a few months back. Is there a chance it could be a software issue causing it? (I will re-install the original CPU to test - but I was wondering if anyone else had a similar problem.) 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. ___ 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.
