I am sending packets at a specific frequency and with a specific gain from one N-210 USRP to another of the same model.
NOTE: I have the transmitting USRP connected to a series of attenuators (so that I don't overwhelm the spectrum analyzer) and then to an RF splitter - one output is connected to a spectrum analyzer and the other output is connected to the receiving USRP. This is how I am reading the receive signal's magnitude.
I am attempting to calibrate the receive signal power measurements (in dBm) that I can visually record from the spectrum analyzer with the RSSI measurements (in dB) that are output into a file by a script (I read them from the text output of the
ofdmflexrframe_rx function). My plan is to come up with a linear correction factor to relate RSSI measurements to the receive signal power measurements from the spectrum analyzer.
I read on Wikipedia:
RSSI is the relative received signal strength in a wireless environment, in arbitrary units.
I also read this from a response to a USRP user's question about RSSI measurements:
[The] Received Signal Strength [Indicator is] always relative to some signal model, incorporating considered bandwidth, assumptions on the modulation scheme, duration of transmission, generally: It's a estimation of received signal strength based on some property of the received signal.
Now, I think that comparing the receive signal power levels on the spectrum analyzer with the RSSI measurements that function provides is not the right way to come up with a correction factor.
- What is the difference between RSSI measurements and the dBm values that I record from the spectrum analyzer?
- Is it possible to relate these RSSI measurements to the receive signal power levels that I record from the spectrum analyzer?
- If I cannot relate these two measurements by a correction factor, is there a way to obtain the receive signal power measurements (in dBm) programmatically (GNUradio perhaps)? (NOTE: I don't believe there is any way to obtain the receive signal power measurements through the library that contains the function I linked above)