On Mon, Feb 18, 2013 at 7:35 PM, Richard Solomon <w1...@earthlink.net>wrote:
> I also have both (two RbO's and 4 GPSDO's). I'll take the GPSDO any day. > This is not a, "which one is better," question. It is a question of what is the job you are trying to do. It is useful to understand the differences. Certainly the long-term stability of the GPSDO is better because the reference oscillator is always being corrected back to the correct time, i.e. long term number of cycles. But in the short term, variations in the GPS satellite geometry can cause the GPSDO to exhibit short-term frequency errors. Of course, long-term these are corrected back out but if one was comparing one would notice small short-term variations in the frequency of the GPSDO while the RbO showed more stability. So the question is, which is more important? Of course, could could have a GPS-disciplined Rb reference. Now you get the best of both worlds, i.e. dead-nuts accurate long term stability with outstanding short-term stability. And the other thing that many people seem to forget about is the phase noise of the disciplined reference oscillator. That may have substantial effect on the performance of the receiver over and above the frequency accuracy. So, when it comes to the question of, "which is better, an Rb reference oscillator or a GPS disciplined oscillator," the answer is a resounding, "it depends." I still hold that, for most people looking to increase the frequency stability and accuracy of their Flex 1500 or 5000, an Rb reference like the LPRO-101 is simpler for the following reasons: 1. No outside GPS antenna needed. 2. The LPRO-101 runs on a single 19V supply (I use an old laptop power supply) while the Thunderbolt needs +5V, +12V, and -14V. I use a cheap laptop DC supply to run my LPRO-101 from the shack 12V supply. 3. The output of the LPRO-101 may be fed to the external reference input with no attenuation. 4. The LPRO-101 has relatively low phase noise. Like I said, I have both but find the LPRO-101 Rb reference easier to use and its accuracy still exceeds the tuning accuracy of the radio. -- Brian Lloyd, WB6RQN/J79BPL 3191 Western Dr. Cameron Park, CA 95682 br...@lloyd.com +1.767.617.1365 (Dominica) +1.916.877.5067 (USA) _______________________________________________ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flexradio.com/ Homepage: http://www.flexradio.com/
