Today's video from Corrosive on the SignalsEverywhere YouTube channel discusses Bias Tee's. He explains what they're used for, and how to enable them on various SDRs. In particular he shows how to use the software to enable the bias tee on our RTL-SDR Blog V3 dongles. A bias tee allows you to power antenna side devices like low noise amplifiers by putting DC voltage on the coaxial cable.
The RTL-SDR Blog V3 dongle has a built in software selectable bias tee. By default it is turned off, and can easily be turned on by running some simple software. Instructions are available on the V3 users guide at www.rtl-sdr.com/V3.