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Re: [Discuss-gnuradio] An interesting application for my new USRP... som

From: n4hy
Subject: Re: [Discuss-gnuradio] An interesting application for my new USRP... some input requested
Date: Thu, 26 May 2005 16:55:09 +0000
User-agent: Mozilla Thunderbird 1.0.2 (Windows/20050317)

Let me add that if done off line and the 10 Mhz Reflock II based oscillator is
used,  then you can use a forward backward algorithm tracking the oscillator
to resample the other channels to remove all systematic biases/errors up to the accuracy and the lock of the 10 Mhz oscillator. Not much can be done with the phase noise of course. If you want, you can multiply that 10 Mhz to 60Mhz and use it as the external clocking (rather than the 64 Mhz oscillator now on board). The Reflock II could also be used to lock a 64 Mhz oscillator as well, given an external reference such as GPS, and then all sample rates will be as needed. This implies having a VCXO that runs at 64 Mhz. The phase noise would be low since you are taming a crystal oscillator. Thus the accuracy can be improved in either of these ways.
A TC-VCXO would be ideal.  Barring that,  put a thermal tab on it.  DB6NT


makes a slip over microprocessor controlled "dress" for keeping a crystal at nearly 40C. It is called the QH40A.

Go here:


and click on crystal heater.


n4hy wrote:

None of this work needs to be done realtime. It can be done after the fact on recorded digital signals. May I suggest that you take that Reflock II tamed
10 Mhz oscillator and record it in parallel.


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