[time-nuts] Symmetricom S200 Antenna Disgnostic and Replacement Recommendation
All, Does anyone have a good recommendation for an inexpensive but effective replacement antenna for a Symmetricom/Microsemi S200 or S250? These units use a 12V receiver and also have an antenna open/good/short status alarm. My antenna recently went to showing open alarm and the receiver will no longer lock. I purchased an inexpensive marine-type antenna which appeared to be 12V tolerant but triggers the short alarm. I know that it is possible that the antenna could be fine like this and the alarm could be ignored, but even still I would prefer that the antenna current alarm remain functional. Does anyone have a recommendation for an effective but inexpensive antenna that tolerates 12V and consumes an appropriate amount of current to pacify the alarm? In the event that my antenna was damaged by something like a nearby lightning strike that also could have damaged the receiver, I would prefer to at least test with an appropriate antenna before either risking more damage or deciding to attempt a more invasive repair. Thanks for any info! John Laur K5IT ___ 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] OCXO with ADEV of 1E-13 on Pluto Mission
The link below is an updated version of the same paper: http://www.boulder.swri.edu/~tcase/NH%20RF%20Telecom%20Sys%20ID1369%20FINAL_Deboy.pdf It has considerably more detail on the RF components as well as the USO module for which there is an entire page of additional information and a block diagram. Whatever happened to the spare components probably happened a decade ago at any rate. Not that they wouldn't eventually wind their way to ebay anyway! Regards, John K5IT On Thu, Jul 16, 2015 at 10:17 AM, John Stuart wrote: > Here is an interesting link to the New Horizons Mission to Pluto radio > system design. > Note last section describes an OCXO with ADEV = 1E-13 at 1s, and aging rate > of <1E-11 per day. > > http://www.uhf-satcom.com/amateurdsn/Paper-969.pdf > > > > I wonder if their spares will show up on eBay? > > > > John Stuart, KM6QX > > Lafayette, CA > > ___ > 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] ULA launch of GPS IIF-10
Somewhere along the line I got added to the email blast list from ULA's communications group. I'm not sure I really belong on it, but it's fun to get space news hot off the press from time to time. This morning's message might be an interesting news bit for the time-nuts: > Lift off! ULA Atlas V Launches GPS IIF-10 for the U.S. Air Force > The United Launch Alliance Atlas V rocket lifted off at 11:36 a.m. EDT. This is the 10th of the final 12 satellites in block II. Best of luck for a good insertion and deployment which should be happening right now. Cheers, John K5IT ___ 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] beaglebones, time, web services
A small task queue or message queue would serve the purpose of tying the webserver to the other external tasks: 1) Web server queues job; 2) polls via ajax for status or they could run syncronously. Python is not my forte but there are a number that look like they integrate very well with python. A couple that look like they might be suitable from a quick google are huey or celery. John On Tue, Jul 7, 2015 at 6:13 AM, Bob Camp wrote: > Hi > > Having done this on *very* small machines with cgi before, the lag has > never been > an issue. Yes, the things I do are “tweaks” to variables, or data > requests. I do not try > to spawn a piece of code to compute PI to 800 places and wait for the > result. > > Bob > > > On Jul 6, 2015, at 10:24 PM, Jim Lux wrote: > > > > On 7/6/15 3:19 PM, Tom Harris wrote: > >> Since you want simple just use a CGI script written in your language of > >> choice. Very easy technology to learn, Python has support libraries out > of > >> the box if you want. You have a webpge with carious simple controls on > it > >> like buttons etc, you click a special button that posts a request to a > URL, > >> the webserver runs a script that generates the response, the webserver > >> serves it out, your browser displays it. Why bother with learning a > >> framework? Messing about with mechanics is far more fun! > >> > >> > > > > > > > > The only hiccup with the cgi approach (and with "directly code the > action in the guts of the server" like with flask) is that the subprocess > that's spawned has to complete before control returns (e.g. to serve stdout > to the user). So if you want to fire off a task that will run in parallel > with the webserver's other stuff, you need to have some sort of > interprocess communication (e.g. a named pipe, socket, file, MPI > communicator, etc.). (or you do something like run "at" or "batch", which > is basically using a file as a interprocess communication, and the at > daemon watches the file) > > > > > > > > ___ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PCI-E Serial Card For Windows NTP?
> However, it has been noted that the Raspberry Pi has some limitations for > this purpose, not the least of which is having a USB connected ethernet port. Windows 7 in particular offers it's own set of trouble. Based on my experiences with both platforms, it will be harder to extract consistent and predictable NTP performance from Win7 than Raspberry Pi. Many others have suggested that you experiment with BeagleBone Black; is there a particular reason that you prefer to take the long route? The out-of-box performance is already very good, and there is plenty of remaining challenge and accuracy available from engaging the hardware timers, using a RTOS, and even replacing the main oscillator. I believe the ethernet controller is even capable of PTP should you wish to go beyond NTP (never tried it myself). John On Thu, Jun 25, 2015 at 8:55 PM, Brian M wrote: > Trying not to go offtopic. If there are specific lists for this type of > nuttery, contact me off list - would love to learn and discuss more. > That said - if you're going to test the impact on latency for interrupt > coalescing, I'd suggest using sockperf ping pong test: > https://github.com/mellanox/sockperf > Should reveal a bit more than a simple icmp ping test can. Use the --pps > flag to test a variety of packet rates. Should help show the effect of > coalescing. > - Brian > > On Thu, Jun 25, 2015 at 13:40 Hal Murray wrote: > >> >> I know next-to-nothing about Windows. >> >> Serial ports are pretty standard. I'd get the cheapest card. I'd probably >> pay a bit more for a second port. It might be handy tomorrow. >> >> One difference between chips is the depth of the FIFO. >> >> PCI card now come in two heights. Make sure you get the right one. The >> short ones don't have room for a second connector. (Some cards come with >> two >> face plates. You can swap in/out the other one if you can use a >> screwdriver.) >> >> >> The other thing to keep an eye on is interrupts from the Gigabit ethernet. >> With a lot of short packets, you can get in trouble spending all your CPU >> time in the interrupt handler. Some hardware is setup to batch interrupts. >> The idea is to delay an interrupt for a while in hopes that more packets >> will >> arrive and get processed as a batch. You may want to turn that off. It's >> a >> tradeoff between latency and CPU usage. You may be able to measure it with >> something like ping. >> >> >> >> -- >> 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. >> > ___ > 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] More recent information on BG7TBL GPSDO?
Bob, Understood regarding NTP; I just thought if it had to be monitored anyway it could pull double duty. I guess that is not so important. It appears they are selling well enough to keep up with or otherwise deplete their supply of surplus OCXOs, so there is probably little motivation to fix problems. Maybe some additional information will surface in the future. The design looks simple enough perhaps if the hardware is documented properly an alternative firmware might be developed - that is a long shot I know. John On Tue, Apr 28, 2015 at 4:47 PM, Bob Camp wrote: > Hi > > The accuracy required by NTP can be met with a <$20 GPS board. It’s much > easier to simply do a stand alone device than to try to tie everything > together. > Fewer ground loops / fewer things to go wrong / easier to keep running. > > The frequency offset in the device appears to be a design choice made by > the > people running the project. There is no way to find out if they have > changed their > design other than buying more devices. That *assumes* that the later > devices > have later firmware versions …. > > Bob > > > On Apr 28, 2015, at 2:57 PM, John Laur wrote: > > > > Hello all. Long time listener; first time caller. > > > > I picked up one of the BG7TBL GPSDO units from Ebay, and I am still > waiting > > for it to arrive. I understand it has its flaws, but my needs are fairly > > simple, and I think it will serve. > > > > My intent is to use it as a reference which is better than the 0.1ppm > TCXO > > in my HF radio, an ANAN-100D (HPSDR architecture); I would like a PPS > > reference so that I can experiment with timestamped IQ samples; and I > would > > like to build an NTP server using a BeagleBone Black. I think this will > > serve to do these things even if it is not the ideal equipment. > > > > I have read I believe all of the previous discussion on this list over > the > > past few months including the excellent study by John KE5FX, and I had a > > few questions to see if there had been any new developments. I understand > > some may have communicated with the designer as well. > > > > Does anyone else have further information on the serial interface? Is the > > NMEA data directly to/from the U-Blox module or does the internal > firmware > > filter/augment it to allow monitoring or tuning of other internal > > parameters - for instance can one set cable delay? What is its > suitability > > for running as a GPS/PPS reference for an NTP server? Any other software > > suggestions for keeping an eye on it? > > > > Second, has the small frequency error identified by John been corrected, > or > > is it a problem endemic to the design (I think maybe this was identified > as > > a resolution limit of the DAC providing OCXO control voltage; could it be > > dithered?) > > > > As this is my first moderately accurate device in the shack, is my best > > approach just to put it on the shelf, leave it on for a long time, and > > trust it? I can see how its easy to begin the slide when there is only > one > > clock to stare at skeptically. > > > > Thanks, > > John Laur > > K5IT > > ___ > > 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.
[time-nuts] More recent information on BG7TBL GPSDO?
Hello all. Long time listener; first time caller. I picked up one of the BG7TBL GPSDO units from Ebay, and I am still waiting for it to arrive. I understand it has its flaws, but my needs are fairly simple, and I think it will serve. My intent is to use it as a reference which is better than the 0.1ppm TCXO in my HF radio, an ANAN-100D (HPSDR architecture); I would like a PPS reference so that I can experiment with timestamped IQ samples; and I would like to build an NTP server using a BeagleBone Black. I think this will serve to do these things even if it is not the ideal equipment. I have read I believe all of the previous discussion on this list over the past few months including the excellent study by John KE5FX, and I had a few questions to see if there had been any new developments. I understand some may have communicated with the designer as well. Does anyone else have further information on the serial interface? Is the NMEA data directly to/from the U-Blox module or does the internal firmware filter/augment it to allow monitoring or tuning of other internal parameters - for instance can one set cable delay? What is its suitability for running as a GPS/PPS reference for an NTP server? Any other software suggestions for keeping an eye on it? Second, has the small frequency error identified by John been corrected, or is it a problem endemic to the design (I think maybe this was identified as a resolution limit of the DAC providing OCXO control voltage; could it be dithered?) As this is my first moderately accurate device in the shack, is my best approach just to put it on the shelf, leave it on for a long time, and trust it? I can see how its easy to begin the slide when there is only one clock to stare at skeptically. Thanks, John Laur K5IT ___ 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.
