PACTOR is an evolution of “AMTOR” and “PACKET RADIO”. It is a radio modulation mode that uses a combination of Frequency Shift Keying (FSK) and Automatic Repeat Query (ARQ) protocol for the sturdy error detection and data information throughout. The frequency range of PACTOR is between 1MHz and 30MHz. It is employed in several fields such as amateur radio operators, marine radio stations, and radio stations to send and receive the digital information, military and government in Department of Office of Homeland Security.

The word PACTOR was developed from the Latin word referred to as “The Mediator”. Then it was developed by Special Communication Systems (SCS) and came into public throughout the year 1991. It had been developed to enhance the reception of digital data when the received signal was weak and noisy. It combines the bandwidth efficiency of packet radio with the error correction (CRC) and the ARQ of AMTOR. Amateur radio operators were instrumental in developing and implementing the digital modes.

PACTOR is a combination of standardized modes used by the Amateur and the Marine radio operators for FSK radio teletype (RTTY) to transfer digital information over shortwave bands. For high frequency data transmission the amateur radio operators uses the medium power of 100watts from 100km to 4000km distance. For long distances the effective frequency communication needs special attention for the error correction and data which is repeated. To reduce the amount of data sent, an on-line compression data is used along with the ARQ memory error correction. From this PACTOR achieves power efficiency greater than the older protocols such as packet, AMTOR and RTTY.

PACTOR has a very narrow waveform and occupies the band space of 300 baud packet. It also has a rapid time-division duplexing and depending on the PACTOR protocol versions and radio frequency conditions, the transmission speed ranges from 20 to 5200 bits per second.

To transfer the data between radio stations and the internet, a robust network of PACTOR stations has been established, for extending internet access to ocean primarily based and other isolated users led by the volunteers involved with Winlink under the auspicious of ARSFI.
Except the level 1 (P1) mode in PACTOR, other modes are publically documented and therefore the third parties can be easily monitored and decoded using the Raspberry Pi software package or PMON utility in the modem itself.

1) PACTOR Radio consists of High Frequency (HF) transceiver, a computer and a terminal node controller. The software package which is running on the computer will drive the terminal node controller. This amateur program is used for the purpose of Airmail.
2)PACTOR is also used by Amateur Boarding System operators to exchange the general public messages and open conversations across the world.
3)PACTOR is employed by the NTSD (digital) portion of the ARRL’s National Traffic System (NTS) to pass digital ARRL Radiograms.
4)Newer PACTOR modes are used to transfer the large binary data files and Internet e-mail, particularly via the Winlink global e-mail system.
5)The SailMail network transfers e-mail on behalf of marine stations.