[time-nuts] Noise source measurement

[Javier Herrero]

Hello all,

Perhaps a bit OT, but I'm measuring the output noise density of a noise 
source at a puntual frequency. I've fed the noise output to a 8566B 
spectrum analyzer, BW set to 1MHz and video BW set to 1kHz so the 
displayed trace is flat. I obtain a measurement of -45dBm, and I 
understand that the noise density then is -105dBm/Hz.

 From design variables, I was expecting a somewhat lower value, around 
-110dBm/Hz, but between the NoiseCom noise source and the output there 
are several things (attenuator, filter, amplifier, directional coupler, 
variable attenuator, ...), so perhaps there are slight differences 
between estimated insertion gains and losses accumulate up to 5dB. 
Before dismount the system and look directly at the noise source output 
and measure the losses/gains of each element, I would like to know if I 
am doing this mesasurement right or am I commiting some mistake?

Thanks! Best regards,

Javier, EA1CRB