PACTOR

PACTOR is a radio modulation mode used by amateur radio operators, marine radio stations, and radio stations in isolated areas to send and receive digital information via radio. A robust network of PACTOR stations has been established to relay data between radio stations and the Internet, extending Internet access to sea based and other isolated users. PACTOR utilizes a combination of simple FSK modulation, and the ARQ protocol for robust error detection and data throughput. Generational improvements to PACTOR include PACTOR II, PACTOR III, and PACTOR IV which are capable of higher speed transmission. Pactor modes other than level 1 (P1) are not open source and therefore cannot be decoded by anyone who hasn't invested in a proprietary modem.

PACTOR (Latin: The mediator) was developed by Special Communications Systems GmbH (SCS) and released to the public in 1991. It was developed in order to improve the reception of digital data when the received signal was weak or noisy. PACTOR is an evolution of both AMTOR and packet radio; its name is a portmanteau of these two technologies. PACTOR combines the bandwidth efficiency of packet radio with the error-correction (CRC) and automatic repeat request (ARQ) of AMTOR. Amateur radio operators were instrumental in developing and implementing these digital modes. PACTOR is most commonly used on frequencies between 1 MHz and 30 MHz.

PACTOR is a set of standardized modes used by Amateur and Marine radio operators for FSK radioteletype transfer of digital information over shortwave bands.

PACTOR radio equipment consists of an HF transceiver, a computer and a terminal node controller. Software running on the computer drives the terminal node controller. The most commonly used Amateur program for this purpose is Airmail.

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