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Upverter

Using an SDR to receive signals at frequencies from 24 MHz up to the GHz range is quite common (RTL2832 + R820, for example), but there is nothing dedicated and efficient for HF, only modes like direct sampling. To solve this problem, we need to raise the HF frequency up to VHF using an upverter.

For an upverter we need a mixer, adding the input frequency to that of a local oscillator:

Mixer diagram: the input signal is added to the local oscillator

Using a 10 MHz input signal and a 50 MHz local oscillator, we get 60 MHz at the SDR input.

There are also commercial options with a built-in upverter, such as the RTL-SDR V4.

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