Comparing the performance of SDRPlay RSP1 with the tinySA for HF measurements
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A well known fairly cheap SA solution for HF applications is the RSP1 combined with PC SW.
I thought it would be interesting to compare the tinySA performance with the RSP1 as the RSP1 also uses an (internal) upconverter when doing measurements below 50MHz. The backend of the RSP1 is a I/Q mixer into a 10bit 10MHz ADC I ensured the scan time for both SA's was comparable. First a 10MHz signal at -20dB. The results are comparable except the RSP1 has a weird -63dB signal at 5MHz. Noise floor of a tinySA is a bit lower Then a test to see how well both SA's handle a 0dB signal. The tinySA starts to show some spurious signals but still fairly clean and the 2nd and 3rd harmonics are still more than 40dB below the fundamental. The RSP1 shows signs of overloading as the 2nd harmonics is only 25dB below the fundamental and many more intermodulation products appear The last test is a -90dBm signal at 10MHz. With a 16k FFT and 125Hz bin size the noise floor of the RSP1 is too high so the signal is not visible where the tinySA drops its noise floor using a 1kHz resolution filter sufficiently to observe the -90dBm signal. Be aware the RSP1 becomes a real-time spectrum analyzer when you are below a 1MHz span which is a big advantage for certain measurements and the FFT based resolutions filters are much better. Only with a 500k point FFT with a 4Hz bin size the noise floor of the RSP1 drops sufficient to have the same SNR as the tinySA A last observation is the excellent linearity of the SI4432 signal strength measurement as the observed levels are within 1 dB of what they should be. -- HBTE Files section:?/g/HBTE/files Erik, PD0EK |
Roger Need