Don wrote:
you guys are reinforcing that just because its' cheap won't mean it won't work.
Of course it doesn't. But keep in mind that "working" spans several orders of magnitude in this area, and what one needs to design and build depends on what degree of "working" one needs to support the uses to which the finished standard will be put. First, there is performance during normal operation (good, continuous satellite tracking) -- ADEV at all taus of interest, PN at all offsets of interest, distortion and spurs, residual AM, stability over temperature, PPS jitter, etc. Then, there is performance with poor satellite visibility, and finally performance in holdover (no satellite visibility) for however long one needs it (if one needs it at all, which many amateurs may not). For some, there will be power consumption issues. There may also be issues of interfacing to monitoring devices, both simple (e.g., LCD status displays) and sophisticated (e.g., computer running Lady Heather or Z38xx). Does it need to work with existing programs, or is writing a new monitoring program part of the project? Then there are the construction issues. Does it need to be assembled entirely from connectorized modules, no soldering required? Or capable of being thrown together on a scrap of perfboard? Or will a PC card be designed? If so, can it use SMT parts? How adaptable must it be, particularly in accommodating different oscillators? Does it need to support rubidium oscillators as well as quartz? Etc., etc., etc.
Thunderbolt and Z38xx commercial GPSDOs are plentiful and relatively affordable, so they are natural benchmarks for any DIY project.
From my perspective, the most interesting development would be an offer by someone with a very well equipped lab to test any DIY GPSDO with a consistent protocol and publish the results. That way, we could all see how the various approaches compare with respect to the characteristics that are most important to each of us.
Best regards, Charles _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
