Marcus explained it better than me in your previous email, but in general, those SDR devices aren't calibrated devices, as in you (the user) can't infer from the sample value the signal power, so the apps (e.g., QSpectrumAnalyzer) can't tell you anything about dBm (power) values, only dB values relative to some point (full scale according to Marcus).
If you want to measure the power values with those SDR devices, you need to calibrate them by fixing the center frequency and the gain, then injecting different levels of power, measuring the dB values you get, and inferring the "dBm vs. dB-level" function (which depends on the center frequency and gain, and possibly other factors). On Wed, Jun 21, 2017 at 5:09 PM GNUBeginner <muratc...@hotmail.com> wrote: > Hello Everybody, > > Could anyone please try to explain to me why I am seeing dB values instead > of dBm in the spectrum analyzer GUIs such as QSpectrumAnalyzer or spectrum > scan programs such as gr-scan or hackrf_sweep. > > Because when I inject a signal with -15 dBm power using 20 dB attenuator > (no > loss - just a short cable from the Vector Signal Generator to the HackRF > One) to the HackRF One, somehow I see -53 dB as peak power. > > Thanks > > > > -- > View this message in context: > http://gnuradio.4.n7.nabble.com/dB-or-dBm-tp64323.html > Sent from the GnuRadio mailing list archive at Nabble.com. > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >
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