[time-nuts] GNURadio USRP for Allan/Phase-noise measurement

John Ackermann N8UR jra at febo.com
Wed Jun 22 15:17:45 EDT 2005

Poul-Henning Kamp wrote:
> Has anybody considered using the GNURadio USRP to measure Allan
> variation and phase-noise of signals ?
> It can sample two input signals at high resolution and speed
> so it should be almost ideal for our purposes...
> http://comsec.com/wiki?UniversalSoftwareRadioPeripheral

I've *considered* it, but haven't done anything about it yet :-).

I do have one of the USRP units, and it is a highly cool piece of 
hardware.  The whole system (including the four ADCs, each 
64msample/sec, 14 bit) is clocked from a single 64MHz oscillator, and 
provision is made to replace the on-board oscillator with an SMA jack. 
My plans are to use a Reflock II 
(http://w3ref.cfn.ist.utl.pt/cupido/reflock.html, and to be available 
from TAPR within the next couple of months) to control a 64MHz VCXO that 
feeds into that SMA...


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