The AN/USQ-124 Tactical Intelligence (TACINTEL) System was a computerized message processing system that made it possible to transmit and receive special intelligence (SI) message traffic via satellite in a controlled environment while simultaneously screening two predetermined subchannels of the Fleet Broadcast transmissions.

SI message traffic may be entered manually via the TACINTEL peripheral equipment or the display terminal keyboard; however, most of the message traffic is entered automatically by systems or facilities connected to TACINTEL. TACINTEL was also capable of direct ship-to-ship interchange and processing of time-sensitive sensor for Indications and Warning, and Over-the-Horizon-Targeting (OTH-T).

The link-control protocol for TACINTEL was adapted to a format required for communication across a DAMA-supported channel. A polling scheme was used that supported a net membership of 23 subscribers within a satellite footprint. A portion of a DAMA 25-Khz channel on each of the FLTSATCOM satellites was allocated for TACINTEL. At subscriber terminals, the baseband equipment is used for handling TACINTEL message traffic as well as for screening two subchannels of Fleet Broadcast transmissions.

At both shore facilities and subscriber terminals, message traffic could be entered via the TACINTEL peripheral equipment such as the tape reader (not applicable to shore) or the display terminal keyboard. Most of the message traffic was entered automatically by systems or facilities connected to TACINTEL at those locations.

TACINTEL baseband equipment used an RF terminal in common with other subsystems at both the shore facilities and subscriber installations. The RF terminal at shore locations was an UHF Transceiver AN/WSC-5(V). At the subscriber installations, the UHF transceiver was an AN/GSC-3(V). The TACINTEL RF channel operated as a half-duplex UHF link, which could be operated at a transmission rate of 4800 Ups, 2400 bps, or 1200 Ups. The modulation of the RF signal is differentially encoded phase-shift keying (DESK).

Source: globalsecurity.org