HI Keep in mind that if you apply pre-filtering, an ADEV plot is lying to you ….
Bob > On Jul 29, 2016, at 6:58 PM, Kevin Rosenberg <ke...@rosenberg.net> wrote: > > Jeff, > > Thanks for your very useful paper Oscillator Metrology with SDRs[1]. I > created a C++ program and checked residuals using a 10 MHz clock split > to the A and B channels of a LFRX and BasicRX boards and sampled at 1 > Mhz. Using boxcar averaging of 1000 samples at 1 kHz, I was impressed > by the low noise floor approaching that of my Timepod which was > several times the cost. I included the Allan Deviation without > averaging showing the sqrt(1000) increase in noise floor without the > averaging[2]. > > I had a question about your experience. You mentioned using a input > signal near the maximum of the USRP’s ADC to get the best SNR. I > reviewed the schematics and application notes. I found a maximum Vpp > mentioned of 3.3V. I was wondering what voltage you were using to > drive the USRPs. When I go above 1.5-2 Vpp, I start getting signal > distortions and not much increase in the amplitude. > > Many thanks for publishing your work in this area. > > Kevin > > [1] > https://arxiv.org/abs/1605.03505 > > [2] > <usrp-pn.png>_______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
