USB to LNB power supply: how I converted my HackRF to a spectrum analyzer to align my SAT-TV dish

A satellite dish is just a parabolic reflector, the real antenna is inside the Low Noise Block downconverter (LNB).

Satellite TV is transmitted in the Ku Band (at least in Europe, in some other parts of the world C band is used instead). More precisely the typical range of frequancy is 10.70 to 12.75 Ghz, frequencies far too high to travel inside a coax cable from an antenna to the receiver. The LNB, installed in the focus of the dish, converts the received signals in the 950-2050 range (using a local oscillator).

Universal LNBs need to receive power from the coax cable. The voltage sent to the LNB can be 13V for vertical polarization) or 18V (for horizontal polarization). Universal LNBs also have two different frequencies for the internal oscillator: 9.75 GHz or 10.60 GHz. A 22khz tone must be sent with the power to enable the higher frequency of the local oscillator.