Re: [Discuss-gnuradio] 64MHz USRP Oscillator

[Wireless Monster]

Hi Chris,
Can you briefly explain in what exactly consists the Software PLL?

All,
I've been trying to set both Tx and Rx to the same frequency and sending a sinusoid to try to measure the frequency offset, but it does not seem to work... it looks like as both Tx and Rx are driven by the same clock, the frequency the offset gets compensated on the Rx signal so it can not be measured... (???)

Anyone has any clue on how to measure it dynamically at the code startup?

Thanks in advance!
[WM]

On Wed, Jul 23, 2008 at 6:57 PM, Chris Stankevitz <address@hidden> wrote:

Wireless Monster wrote:

Hi All,

I am having lots of issues with the USRP  64MHz (20ppm) on board oscillator which does not allow me to get exact and constant RF frequencies out of the RFX900 board. I can not really fix that in SW so I was thinking about replacing the 64MHz crystal with a more precise one. Has anybody a suggestion of which part to use?

I have replaced the crystal with the 20ppm crystal, but I was unable to get an "exact and constant" frequency.  I ultimately added a software PLL to track the clock errors.  Before I upgraded my software PLL, I used a signal generator as an external clock source which worked very well.

Chris