usrp_oscope.py -f 103.3M -d 256
The command above, after executed, will plot the received signal in a 250KHz window centred at 103.3MHz
250KHz because the USRP samples at the rate of 64MSPS and decimation is 256, thus 64M/256 = 250e3 = 250KHz
Similarily if the decimation was 512, then we would have observed the received signal in a 125KHz window
This can be more clear if you see the fft of the signal with the same decimation rate.
You can observe that the length of the fft window will go from 0 to fs/2 and 0 to -fs/2 giving a total observable window of length fs Hz
** The Y axis of usrp_oscope does not show the voltage level, its not calibrated for that. The levels depend on gain settings too.
** usrp_oscope shows real and imaginary part of the complex baseband signal coming from the output of Digital down converter of the USRP
** So the usrp_oscope is actually showing the downconverted frequency, not the actual frequency
The command above, after executed, will plot the received signal in a 250KHz window centred at 103.3MHz
250KHz because the USRP samples at the rate of 64MSPS and decimation is 256, thus 64M/256 = 250e3 = 250KHz
Similarily if the decimation was 512, then we would have observed the received signal in a 125KHz window
This can be more clear if you see the fft of the signal with the same decimation rate.
You can observe that the length of the fft window will go from 0 to fs/2 and 0 to -fs/2 giving a total observable window of length fs Hz
** The Y axis of usrp_oscope does not show the voltage level, its not calibrated for that. The levels depend on gain settings too.
** usrp_oscope shows real and imaginary part of the complex baseband signal coming from the output of Digital down converter of the USRP
** So the usrp_oscope is actually showing the downconverted frequency, not the actual frequency
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