Hackaday has brought to attention a blog post by Kerry Wong which shows how the RTL-SDR can be used as a simple and inexpensive spectrum analyzer. In the past we’ve already posted numerous examples of the RTL-SDR being used as a spectrum analyzer but Kerry’s post discusses some of the do’s and don’ts that you need to think about when using a SDR as a spectrum analyzer and also provides some measurements.
During his tests he discovered that popular software like RTLSDR Scanner and SDR# either distort the spectrum or don’t display the signal amplitude correctly. Only GQRX and osmocom_fft seemed to give an accurate depiction of the spectrum.
Kerry also discusses how to calibrate the spectrum display to show proper power levels, how to set the gain for spectrum analysis and discusses some thoughts on LO leakage.