Re: [Discuss-gnuradio] RSSI calculation

[Marcus D. Leech]

On 30/03/2011 8:33 AM, Fengyuan Gong wrote:
> Shouldn't the second one also read ADC value on the 
> RFX900/1200/1800/2200/2400 and then calculate out the analog signal
> strength?
That function just does a read of the AUX_ADC (apparently a 10-bit 
aux_adc on USRP1), it has no notion that it's an RSSI value--it's
  just an unstructured collection of bits as far as read_aux_adc is 
concerned.

The "calculate out the analog-signal strength" part is essentially up to 
whatever upper-layer software is using the resulting aux_adc
  value, and interpreting it as an RSSI.

In the case of the RFX-series boards, the aux_adc input is connected to 
the *analog* RSSI estimator that's built into the demodulator
  chip--in this case, the sum of two (I and Q) square-law detectors, 
maybe with a little bit of gain.  So the aux_adc values read are
  directly proportional received signal strength.  It's up to your 
software to scale appropriately.