PACTOR uses a combination of simple FSK modulation[citation needed], and the ARQ protocol for robust error detection and data throughput.
[citation needed] PACTOR (Latin: The mediator) was developed by Special Communications Systems GmbH (SCS) and released to the public in 1991.
[citation needed] PACTOR is used by Amateur Bulletin board system operators to exchange public messages, and open conversations across the world.
[2] PACTOR is a set of standardized modes used by radio operators for FSK radioteletype transfer of digital information over shortwave bands.
[3] Effective radio-frequency communications over long distances over hostile radio paths require that special attention be paid to the rate at which data is repeated and error correction.