Bruce Griffiths wrote: > swingbyte wrote: > >> Hi everybody, >> I mentioned some time ago that I had an Ru 10MHz source and I would like >> to calibrate it. I have an hp 5335 counter and a Jupiter GPS with 10kHz >> output. I was wondering if I could use the Ru 10MHz as and external >> clock for the 5335 and then measure the frequency of the 10kHz gps >> locked signal and adjust the Ru to read exactly 10kHz? If I let the >> 5335 average the frequency input it will display 12 digits - how many of >> those are reliable I'm not sure but it seems that this may be an easy >> way for me to check the Ru. >> Is this a viable method or am I missing something - I haven't done a lot >> of research into the time keeping world yet. >> Also, the model Ru I have is the Efratrom frk-h with external frequency >> control. I have had a quick read of the manual but can't find any >> information on how this works. I was thinking this might enable me to >> discipline the Ru to GPS - does anyone know how this works? >> >> Thanks for your help >> Happy holidays >> >> Tim >> >> >> > Tim > > The biggest problem with your proposed measurement scheme is that the > 10kHz signal is no more stable than the PPS output. > The 10kHz output is phase jerked every second to realign it with the UTC > second. > This behaviour is clearly documented in the receiver datasheet. > > Thus to reduce the measurement error due to this instability to better > than 1E-10 or less the counter gate time will need to be around 1000 > seconds or more. > Adjustment to better than 1E-10 will be somewhat problematic not to say > time consuming. > Fortunately the 5335A maximum gate time is 1E7 seconds or about 4 > months, so this may actually be possible. > > Bruce > > _______________________________________________ > 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. > > 1E7 seconds eh? Well, maybe I don't need that degree of accuracy after all. Thanks for the quick response. How are these Ru oscillators calibrated in a commercial environment? what's the likely frequency tolerance on my second hand Ru osc? I need to revise my theory I think - it been a while since I opened the maths books. How do the GPSDO deal with this or is the stability good enough for them? What can I do to improve my confidence in the frequency output of the Ru? I would like to use this Ru as a house standard for all my frequency counters etc. Tim.
_______________________________________________ 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.
