I have a Pluto and an RTL-SDR both connected to a computer. On Matlab, I run such a script:


SAMPLE_RATE = 750e3;              
NUM_SAMPLES = 750e3;              
CENTER_FREQ = 868e6;            
RECEIVER_GAIN = 0;              
TRANSMITTER_GAIN = -10;         

deviceNameSDR = 'Pluto';                                
sdrTransmitter = sdrtx(deviceNameSDR);                  

sdrTransmitter.RadioID = 'usb:0';                       
sdrTransmitter.BasebandSampleRate = SAMPLE_RATE;        
sdrTransmitter.ShowAdvancedProperties = true;           
sdrTransmitter.CenterFrequency = CENTER_FREQ;           
sdrTransmitter.Gain = TRANSMITTER_GAIN;                 

txWaveform = ones(750e3,1);

sdrTransmitter(txWaveform); %Transmit tone

In the SDR-Console, I listen to the broadcast at a frequency of 868e6 Hz. When I run the script with a gain of -10 dB, the screen shows that the peak is saved. However, when I run the script at -50 dB gain, a peak appears and then it disappears. And the question is why at high gain (-10 dB) the peak remains, but at -50 dB this does not happen? Here the image of sdr-consoleThe result of the script at -10 dB

The result of the script at -50 dB

  • $\begingroup$ the title of your question does not match the question text $\endgroup$ Oct 28, 2022 at 12:18
  • $\begingroup$ So you are transmitting a short signal from the PlutoSDR, testing at either one level or another. You are receiving this signal in SDR-Console via an RTL-SDR. In both cases the signal shows up in the waterfall, but only the louder tests get a "peak hold" in the graph above the waterfall? $\endgroup$ Nov 1, 2022 at 19:55
  • $\begingroup$ yes. when i am transmitting signal on -10 dB peak still remains. But when i set gain on -50 dB peak is disappear $\endgroup$
    – Count Zero
    Nov 7, 2022 at 6:17


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