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PACTOR is a radio modulation mode used by amateur radio operators, marine radio stations, military or government users such as the United States Department of Homeland Security, and radio stations in isolated areas to send and receive digital information via radio.

PACTOR is an evolution of both AMTOR and packet radio; its name is a portmanteau of these two technologies' names. PACTOR uses 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 is most commonly used on frequencies between 1 MHz and 30 MHz.

History

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PACTOR (Latin: The mediator) was developed by Special Communications Systems GmbH (SCS) and released to the public in 1991.

PACTOR was developed in order to improve the reception of digital data when the received signal was weak or noisy. It 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.

Current uses

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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.

PACTOR is used by Amateur Bulletin board system operators to exchange public messages, and open conversations across the world. It is also used by the NTSD (digital) portion of the ARRL's National Traffic System (NTS) to pass digital ARRL Radiograms. Newer PACTOR modes are used to transfer large binary data files and Internet e-mail, particularly via the Winlink global e-mail system.

The SailMail network transfers e-mail on behalf of marine stations.

Technical characteristics

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

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.

To reduce the amount of data sent, on-line data compression is utilized, along with memory ARQ error correction.

PACTOR utilizes very rapid time-division duplexing, giving PACTOR communications its characteristic cricket-like chirping sound when listened through a single-sideband (SSB) receiver.

Depending on the version of PACTOR protocol used and the radio-frequency conditions, PACTOR transmission speeds range from 20 to 5200 bits per second (bit/s; net rate) or 9000 bit/s gross rate utilizing speed 10 (32-QAM).

The International Telecommunication Union (ITU) emission designators:

• Pactor I is 340HJ2D or 440HJ2D (at a symbol rate up to 200 symbols per second).
• Pactor II is 450HJ2D (at a symbol rate of 100 symbols per second).
• Pactor III is 2K20J2D (at a symbol rate of 100 symbols per second).
• Pactor IV is 2K20J2D or 2K40J2D (at a symbol rate up to 1800 symbols per second).

Availability and monitoring

A robust network of PACTOR stations has been established to transfer data between radio stations and the Internet, extending Internet access to sea-based and other isolated users, led by volunteers involved with Winlink, under the auspicies of ARSFI (a Florida-based non-profit organization).

Pactor modes other than level 1 (P1) are not open source, but are publicly documented and can be monitored and decoded easily over the air by third parties using free Raspberry Pi software ("PMON for Raspberry Pi") or PMON utility on the modem itself.

See also

• Shortwave
• Radioteletype
• Winmor

References

1. ^ Helfert, Hans-Peter (October 1991). "PACTOR—Radioteletype with Memory ARQ and Data Compression". QEX Magazine: 3–6.
2. "Sail-mail e-mail service for yachts via Iridium, Inmarsat, or SSB". Sail Mail. Retrieved 1 September 2010.
3. "PACTOR Packet Teleprinting Over Radio" (PDF). Wavecom. WAVECOM ELEKTRONIK AG. Retrieved 29 May 2021.
4. ^ The PACTOR-2 Protocol (PDF). SCS Spezielle Communications Systeme GmbH.
5. PACTOR-2/3/4 Advanced Data Compression (PDF). SCS Spezielle Communications Systeme GmbH.
6. "More on comparisons of digital HF modes". News. PACTOR. Retrieved 1 September 2010.
7. ^ "Technical details on the Pactor-IV protocol". p4dragon.com. PACTOR IV. Archived from the original on 23 October 2015. Retrieved 25 November 2022.
8. ^ "Summary on SCS Waveforms" (PDF). SCS. Spezielle Communications Systeme GmbH & Co. KG. Retrieved 1 June 2021.
9. "Characteristics of systems operating in the amateur and amateur-satellite services for use in sharing studies" (PDF). International Telecommunication Union. 2017. ITU-R M.1732-2.
10. The PACTOR-3 Protocol (PDF). Spezielle Communications Systeme GmbH.
11. "Characteristics of HF radio equipment for the exchange of digital data and electronic mail in the maritime mobile service" (PDF). International Telecommunication Union. 2021. ITU-R M.1798-2.
12. The PACTOR-4 Protocol (PDF). Spezielle Communications Systeme GmbH.
13. "A brief guide to the elements of Winlink 2000". Winlink 2000. Archived from the original on 12 May 2008. Retrieved 25 November 2022.
14. "Original request to FCC for Pactor I in Amateur Radio by ARRL". 1995.
15. "Pactor I open source published in QEX, TAPR, 1994". Archived from the original on 9 November 2015. Retrieved 25 November 2022.
16. "Downloads". www.scs-ptc.com. Archived from the original on 25 March 2018. Retrieved 25 November 2022.
17. "PMON". www.scs-ptc.com. Retrieved 28 November 2024.
18. "Update Info DR7X00 vers. 1.17". p4dragon.com. Archived from the original (PDF) on 14 June 2020. Retrieved 25 November 2022.

• Steve Ford, WB8IMY (2001). "Chapter 5 - PACTOR". ARRL's HF digital handbook. Newington, CT: The American Radio Relay League. ISBN 0-87259-823-3.{{cite book}}: CS1 maint: numeric names: authors list (link)

External links

• "pactor". scs-ptc.com. Archived from the original on 16 August 2009.
• "PACTOR-4". p4dragon.com. Archived from the original on 23 October 2015.
• "winlink.org".
• "airmail2000.com".
• "Pactor-1 Specification".

v t e Amateur radio digital modes
Frequency-shift keying (FSK)	RTTY AMTOR / SITOR PACTOR CLOVER2000 Packet radio (Bell 103 Bell 202) M17
Multiple frequency-shift keying (MFSK)	Olivia MFSK Contestia JT65 FSK441 JT6M WSPR FT8
Phase-shift keying (PSK)	PSK31 PSK63 Q15X25
COFDM	MT63 (based on PSK)
Non-traditional digital modes	Hellschreiber (Feld-Hell) On–off keying Continuous wave Modulated continuous wave Pulse modulation Frequency-hopping spread spectrum (FHSS) Direct-sequence spread spectrum (DSSS) AMPRNet DAPNET

v t e Amateur radio
Activities	ARDF Emergency communications Contesting DX communication High-speed telegraphy Homebrewing
Culture	History Amateur radio operator Awards DX-pedition Hamfest International operation QSL card Q code Radiosport Vintage amateur radio
Governance	International Amateur Radio Union International Telecommunication Union Frequency allocations ITU prefixes for amateur radio Maritime mobile Licensing
Modes of communication	Voice AM DSB-SC ISB SSB AME FM PM Television ATV SSTV Data/Digital CW ALE AMTOR D-STAR DAPNET EchoLink FT8 Hellschreiber DMT MFSK Packet radio (APRS) PACTOR PSK RTTY Spread spectrum C4FM WIRES-X DMR
Technologies	Amateur radio station Amateur radio software IRLP QRP SDR Satellite Two-way radio Transceivers
Related	Shortwave radio Q code Amateur radio in India

• Digital amateur radio
• History of radio
• Radio technology
• Quantized radio modulation modes
• Packet radio