AO-51 contains an FM repeater with both a 144 MHz and 1.2 GHz uplink and 435 MHz and 2.4 GHz downlinks. Additionally AO-51 contains a digital subsystem that transmits TLM on 70cm and provides complete PACSAT BBS that can be configured on both V and S band uplinks. There is also a 10 meter PSK uplink.

Experimenter's Wednesday is an idea that has been put into action with the Echo Project. Every Wednesday (0001 - 2359 UTC) the satellite is placed into a special mode of operation. Experimenters can use their equipment to communicate with the satellite in various modes including V/U, L/S, HF/U, and others. AO-51 supports digital store-and-forward at speeds upto 76.8 kbps, and a contains a wideband SQRX Receiver. A current schedule of operation is kept up-to-date by the AO-51 Control Team.

With four VHF receivers, two UHF transmitters, six modems, fifty-six channels of telemetry, and various other subsystems AO-51 is quite a complex spacecraft. The two UHF transmitters are connected to four antennas, two in the right-hand circular polarization (RHCP) and two in the left-hand circular polarization (LHCP). Transmitter A is connected to the LHCP antennas and is often used for digital modes. The transmitter often used for analog is connected to the RHCP antenna.