An 8 tone, adaptive, synchronous system manufactured by Thrane & Thrane of Denmark. The system runs at 100bd or 200bd using 8 bit ASCII with data throughput of 300 or 600bps. Primarily designed to be connected directly to a serial port of a computer, the system features auto-dial, subscriber addressing, electronic mail and can be connected to a Fax machine.
The full-duplex, error correcting (24 unit CRC) link protocol is completely transparent to any type of data coding. Used by French Diplo, UK Civil Aviation Authority (National Air Traffic System/NATS datalink, Prestwick/Reykjavik) and Algerian oil companies. This may be logged in some commercial frequency lists as TT2300-ARQ, or TRA-2300. The manufacturer's name for the protocol/coding is TPLEX. 2 distinct modes have been monitored: tfc mode and an idling sequence. 8 tones, 200Hz spacing, ACF=8
Frequencies to try: 5028.7, 5109.7, 7716.7, 7719.7.
