[time-nuts] FS740 Thoughts?
Hi, I'm curious to hear people's thoughts on the SRS FS740 (https://www.thinksrs.com/products/fs740.html) as a lab frequency standard. The phase noise performance of the OCXO and Rb options seem quite good (the same specs apparently apply during GPS disciplining too) | offset | TCXO | OCXO/Rb | | (Hz) | (dBc/Hz) | (dBc/Hz) | |+--+--| | 1 | -90| -108 | | 10 | -104 | -130 | | 100| -125 | -144 | | 1k | -142 | -143 | | 10k| -147 | -148 | | 100k | -149 | -149 | | 1M | -153 | -153 | as does the Allan deviation (during GPS disciplining) | time interval (s) | TCXO | OCXO | Rb | |---+---+---+---| | 0.01 | 1E-10 | 2E-11 | 2E-11 | | 0.1 | 4E-11 | 4E-12 | 4E-12 | | 1 | 3E-11 | 2E-12 | 1E-11 | | 10| 1E-10 | 2E-12 | 6E-12 | | 100 | 6E-11 | 2E-12 | 1E-12 | | 1k| 6E-12 | 3E-12 | 1E-12 | | 10k | 6E-13 | 6E-13 | 3E-13 | | 100k | 6E-14 | 6E-14 | 3E-14 | | 1M| 5E-15 | 5E-15 | 3E-15 | (I used the typical performance plots for the phase noise and Allan deviation data) The OCXO does not exhibit the the hump around 2s seen by the rubidium oscillator option (PRS10) and therefore could be seen as better in applications not requiring the better holdover performance by the Rb. It also provides a pulse output with jitter < 50 ps RMS that could be used as a PPS signal. It can also provide a low noise 100 MHz output signal and can act as a frequency counter and DDS with high resolution and accuracy. And it comes with the schematics! But it's definitely not cheap. Other thoughts/opinions? Matt ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: GPS Elevation Mask Values.
Dan, in recent years I've read that DOD (or some such agency) has been running spoofing tests here and there, but always in remote thinly-populated areas (for what should be obvious reasons). As to why not all your receivers exhibit the "finger", I point out that the appearance of a GPS satellite "in the hole" must be treated as an exception, and different combinations of receiver HW & FW with different analysis & display SW could plausibly react differently to such exceptions. I suppose such behavior should be called "bugs", but I would not be too harsh on the designers unless this "bug" also led to erroneous PVT output. In any event, about all I can say is "What a grand mystery!". Dana On Mon, Nov 15, 2021 at 8:24 PM Dan Kemppainen wrote: > Hi, > > The adafruit board had a run with the LTE-LITE and Ublox. Adafruit board > shows no birds above the north pole. Same as does the LTE-LITE on this > run. Again, the Ublox shows them up there according to LH. (At least > everything is consistent!) (The curious of you can view the attached plots) > > Currently running some logs of raw data from all three GPS modules. > We'll give the logs 24 hours and run them through U-Center tomorrow. > > As for right now, eliminating the antenna and mounting location are the > most important part. It's getting to be winter here, and snow makes > getting to the antenna difficult/dangerous. > > > Dana, > > I would be highly surprised if anyone were spoofing GPS here. We're > pretty much in the middle of nowhere. Besides, why only Ublox modules > giving the fits on LH? > > > Keelan, > > Thus the confusion as to why there's birds above the north pole. This > has happened on two PC's with Two different models of Ublox Modules. Two > other brand modules seem OK on LH. > > Certainly odd. > > Thanks, > Dan > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send > an email to time-nuts-le...@lists.febo.com > To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: HP/Symmetricom 59551A showing wrong date
> Not sure why I would need two sessions. Hal can you explain please? One for reading, one for writing. They probably aren't necessary. putty and similar serial control programs are complicated. I don't use one often enough to have one I'm familiar with. So I tried the low tech approach. It worked, so I kept doing things that way. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
