A satellite modem is the heart of any Earth Station or VSAT uplink. There are several different types of modems, but they can be broadly classified as IF or L-Band modems.

The IF series of modems has a transmit frequency in the 70 MHz or 140 MHz range, and each modem may have a full range of features that determine FEC and Modulation.

L-Band modems are sometimes called RF Modems, and typically transmit and receive in the frequency range of 950 to 1750 MHz. Like their IF cousins they may have a extended range of features for FEC and Modulation, but in addition a DC voltage of 24V or 48V can be present to drive a small BUC.