[time-nuts] Quadrature Phase Noise Measurement

[jimlux]

On 10/11/19 11:25 PM, Anders Wallin wrote:
>>
>>
>> I am keen to measure close in phase noise 1Hz to 1 MHz offset on 100 MHz
>> clocks.
>>
> 
> We have some preliminary results on 100MHz using an Ettus B210 SDR.
> The RF front-end is an AD9361, and if you search on ebay you will find B210
> clones at about half the NI/Ettus price (haven't tried those..)

The ADALM PLUTO has a AD9363 front end (single channel, Zynq backend) 
and runs $99 (or $150) - I don't think it tunes down to 100 MHz, though.

> 
> One issue is ch1-to-ch2 isolation, which isn't stellar on the B210.

"isn't stellar" is sort of an understatement, and the USRPs also have 
significant radiation of the clocks and LOs.


> I'm sure John can enlighten us on the importance of channel isolation for
> digital PN and ADEV measurements ;)
> The brute-force approach may be to use two B210s in parallel?
> 
> gnu-radio is quite good for processing the samples - maybe the digilent or
> red pitaya also have gnu-radio drivers?




> 
> AW
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