System Administration, Reconfigurable Computing and Other Random Topics

How not to use the HackRF One as a spectrum analyzer

A while ago I wrote about how to use the HackRF One as a spectrum analyzer, and mentioned that apart from using its sweep functionality, it could also be used as a real-time 20 MHz spectrum analyzer using any SDR software. I now had to learn about its limitations and possible pitfalls when using it this way.

I wanted to look at the spectrum put out by an RF transmitter when transmitting a simple sine wave, i.e., an unmodulated carrier. In particular, I wanted to know about any nearby spurs, so looking at it with a high-bandwidth SDR seemed to be a good idea. So I connected the transmitter to the HackRF One, using appropriate attenuation. Looking at the spectrum put out by the transmitter gave me a bit of a shock:

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