RF Receiver (w ADC) tests - How to?

[mmwicant]

Given receiver setup is
input RF generator (signal or noise ),
and
output after ADC is in the digital domain.
Can you tell or point me to typical tests procesdures of common receiver characteristics?
(e.g. SFDR, NF, IP3, ENOB etc.)
Thanks

 

[G4BCH]

Google sdr testing or similar search term there is a lot out there that can help you

 

[mmwicant]

Is it possible to measure NF and IP3 from antenna port to digital domain past the ADC?

 

[G4BCH]

Noise figure can be measured just like any other receiver.
IP3 again can be measured in a similar way to a linear receiver, you can do an FFT of the ADC output for different I/P levels. The result of this measurement needs to be treated with some caution. If the ADC clips then the measurement falls apart, as will the perceived performance of the receiver. There is no gradual degradation of performance as there is with a linear receiver; if the ADC clips all hell gets let loose. It is perhaps arguable that IP3 is not a very useful measurement for a digital receivers spurious performance. An IP3 measurement , having only two tones made on a wide bit width ADC may give you a false sense of security as to how the receiver will perform under real world high signal level conditions where multiple carriers could overload the ADC.
The pdf link below explains it better than I can here.

https://www.ab4oj.com/sdr/sdrtest2.pdf

 

[vfone]

Is not such easy to measure the noise figure of an ADC:

https://www.analog.com/media/en/training-seminars/tutorials/MT-006.pdf

Idealy would be to do a BER (bit error) test, which is direct related to the thermal noise:

https://www.analog.com/media/en/technical-documentation/tech-articles/less-than-one-in-a-quadrillion.pdf