[time-nuts] Spectrum Analyzer Specifications

Charles Steinmetz csteinmetz at yandex.com
Wed Mar 23 16:20:01 EDT 2016


Peter wrote:

>May I suggest the use of a software defined receiver (SDR) used with 
>suitable attenuators on its antenna input.

The task the OP needs performed is to simultaneously receive a CW 
signal at ~ +13dBm, while at the same time resolving and 
differentiating sidebands as close as fractions of a Hz at ~ -80dBm 
and lower.  Yes, the signal can be attenuated (say, CW signal at 
-10dBm and close-in sidebands at -103dBm and below, or CW signal at 
-30dBm and close-in sidebands at -133dBm and below).  Anyway you cut 
it, that is a dynamic range of more than 90dB at frequency offsets of 
fractional Hz.  The phase noise of the receiver's LO will completely 
swamp the phase noise of the oscillator being tested, by tens of dB 
(called reciprocal mixing).

Best regards,

Charles




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