Re: [Discuss-gnuradio] GPS carrier tracking, USRP oscillator performance

2007-03-09 Thread Matt Ettus
Peter Monta wrote: Could FPGA jitter be contributing? It can be hundreds of picoseconds, but whether there would be low-frequency content in the jitter spectrum I don't know. FPGA jitter might be contributing, but there shouldn't be much at low frequency. You could try measuring this by s

[Discuss-gnuradio] GPS carrier tracking, USRP oscillator performance

2007-03-09 Thread Peter Monta
I tried Greg Heckler's suggestion of minimizing the reference divisor---when running rx_cfile.py, giving a frequency of 1.57542G results in a reference divisor of 8, whereas a frequency of 1.574G decreases this to 2. (I also probed at the chip and saw the same inexplicable factor of two disparity