PACTOR
Encyclopedia
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 an almost ideal combination of simple FSK
modulation, and the ARQ protocol for robust error detection and data throughput. Generational improvements to PACTOR include PACTOR II and PACTOR III, which are capable of higher speed transmission.
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.
on shortwave amateur and marine radio. Newer versions are used by amateur radio operators to transfer large binary data files and to accomplish Internet E-mail access over shortwave radio. Winlink
is a global communications system which uses PACTOR. PACTOR is also used by the sailmail
network for e-mail transfer over U.S. Federal Communications Commission
assigned Marine radio frequencies.
Amateur radio operators and Marine operators use similar equipment to send and receive data using the PACTOR digital mode. The equipment consists of an HF transceiver, a computer and a terminal node controller
. Software running on the computer controls the terminal node controller. The most commonly used program for this purpose is Airmail.
PACTOR is also used by the ARRL's National Traffic System (NTS)
for digital transmission of NTS Traffic, referred to as NTSD. Pactor is also used by Amateur Bulletin Board operators to exchange public messages and open conversations across the world.
To reduce the amount of data sent, on-line data compression is utilized, along with memory ARQ error correction. By combining these open technologies, PACTOR achieves a power efficiency much greater than that of older protocols such as packet, AMTOR
, or RTTY
. PACTOR has a very narrow waveform and occupies the same band space as analog 300 baud packet.
PACTOR utilizes very rapid Time-Division Duplexing, giving PACTOR communications its characteristic cricket-like chirping sound when listened through a single-sideband
receiver.
Depending on the version of PACTOR protocol used and the radio-frequency conditions, PACTOR transmission speeds range from 20 to 200 characters per second .
Like all digital radio modulation modes, PACTOR transmissions have the potential to disrupt other modes of communication on the same or nearby frequencies. Radio operators using PACTOR are encouraged to follow "good operating practices" to ensure that they do not interfere with other stations. In certain configurations, Pactor II and III utilize a proprietary data compression technology. As the data is compressed, and the decompression algorithm is not publicly known, the contents of PACTOR transmissions are unreadable to anyone without a PACTOR capable terminal node controller.
Amateur radio
Amateur radio is the use of designated radio frequency spectrum for purposes of private recreation, non-commercial exchange of messages, wireless experimentation, self-training, and emergency communication...
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 an almost ideal combination of simple FSK
Frequency-shift keying
Frequency-shift keying is a frequency modulation scheme in which digital information is transmitted through discrete frequency changes of a carrier wave. The simplest FSK is binary FSK . BFSK uses a pair of discrete frequencies to transmit binary information. With this scheme, the "1" is called...
modulation, and the ARQ protocol for robust error detection and data throughput. Generational improvements to PACTOR include PACTOR II and PACTOR III, which are capable of higher speed transmission.
History
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 AMTORAMTOR
AMTOR is a type of telecommunications system that consists of two or more electromechanical teleprinters in different locations that send and receive messages to one another. AMTOR is a specialized form of RTTY protocol...
and packet radio
Packet radio
Packet radio is a form of packet switching technology used to transmit digital data via radio or wireless communications links. It uses the same concepts of data transmission via Datagram that are fundamental to communications via the Internet, as opposed to the older techniques used by dedicated...
; its name is a portmanteau of these two technologies. PACTOR combines the bandwidth efficiency of packet radio
Packet radio
Packet radio is a form of packet switching technology used to transmit digital data via radio or wireless communications links. It uses the same concepts of data transmission via Datagram that are fundamental to communications via the Internet, as opposed to the older techniques used by dedicated...
with the error-correction (CRC) and automatic repeat request (ARQ) of AMTOR
AMTOR
AMTOR is a type of telecommunications system that consists of two or more electromechanical teleprinters in different locations that send and receive messages to one another. AMTOR is a specialized form of RTTY protocol...
. 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.
Current uses
PACTOR is an established standard for FSK radioteletypeRadioteletype
Radioteletype is a telecommunications system consisting originally of two or more electromechanical teleprinters in different locations, later superseded by personal computers running software to emulate teleprinters, connected by radio rather than a wired link.The term radioteletype is used to...
on shortwave amateur and marine radio. Newer versions are used by amateur radio operators to transfer large binary data files and to accomplish Internet E-mail access over shortwave radio. Winlink
Winlink
Winlink, also known as the Winlink 2000 Network, is a worldwide radio messaging system that mixes internet technology and appropriate amateur radio radio frequency technologies. The system provides radio interconnection services including: email with attachments, position reporting, graphic and...
is a global communications system which uses PACTOR. PACTOR is also used by the sailmail
Sailmail
SailMail is radio based e-mail system designed for yacht owners operating outside of areas of internet service. Much of its underlying technology is built upon the Winlink software originally developed by amateur radio enthusiasts....
network for e-mail transfer over U.S. Federal Communications Commission
Federal Communications Commission
The Federal Communications Commission is an independent agency of the United States government, created, Congressional statute , and with the majority of its commissioners appointed by the current President. The FCC works towards six goals in the areas of broadband, competition, the spectrum, the...
assigned Marine radio frequencies.
Amateur radio operators and Marine operators use similar equipment to send and receive data using the PACTOR digital mode. The equipment consists of an HF transceiver, a computer and a terminal node controller
Terminal node controller
A terminal node controller is a device used by amateur radio operators to participate in AX.25 packet radio networks. It is similar in function to the Packet Assembler/Disassemblers used on X.25 networks, with the addition of a modem to convert baseband digital signals to audio tones.The TNC was...
. Software running on the computer controls the terminal node controller. The most commonly used program for this purpose is Airmail.
PACTOR is also used by the ARRL's National Traffic System (NTS)
National Traffic System
The National Traffic System is an organized network of amateur radio operators sponsored by the American Radio Relay League for the purpose of relaying messages throughout the US and Canada....
for digital transmission of NTS Traffic, referred to as NTSD. Pactor is also used by Amateur Bulletin Board operators to exchange public messages and open conversations across the world.
Technical characteristics
HF data transmission by radio amateurs uses medium power (100 watts) over long distances (100 to 4000 km). Effective radio-frequency communications over such 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. By combining these open technologies, PACTOR achieves a power efficiency much greater than that of older protocols such as packet, AMTOR
AMTOR
AMTOR is a type of telecommunications system that consists of two or more electromechanical teleprinters in different locations that send and receive messages to one another. AMTOR is a specialized form of RTTY protocol...
, or RTTY
Radioteletype
Radioteletype is a telecommunications system consisting originally of two or more electromechanical teleprinters in different locations, later superseded by personal computers running software to emulate teleprinters, connected by radio rather than a wired link.The term radioteletype is used to...
. PACTOR has a very narrow waveform and occupies the same band space as analog 300 baud packet.
PACTOR utilizes very rapid Time-Division Duplexing, giving PACTOR communications its characteristic cricket-like chirping sound when listened through a single-sideband
Single-sideband modulation
Single-sideband modulation or Single-sideband suppressed-carrier is a refinement of amplitude modulation that more efficiently uses electrical power and bandwidth....
receiver.
Depending on the version of PACTOR protocol used and the radio-frequency conditions, PACTOR transmission speeds range from 20 to 200 characters per second .
Criticism
Cost is an important consideration when choosing PACTOR equipment. PACTOR I is open technology and modems can be purchased in the $50–$150 price range and are in ample supply. The two enhanced modes, PACTOR II and PACTOR III, are much faster but have been kept proprietary by the German company, SCS, that developed them. As a result, SCS is the only source for modems capable of these modes. The price of these modems—in some cases as much as a HF radio—discourage many potential users .Like all digital radio modulation modes, PACTOR transmissions have the potential to disrupt other modes of communication on the same or nearby frequencies. Radio operators using PACTOR are encouraged to follow "good operating practices" to ensure that they do not interfere with other stations. In certain configurations, Pactor II and III utilize a proprietary data compression technology. As the data is compressed, and the decompression algorithm is not publicly known, the contents of PACTOR transmissions are unreadable to anyone without a PACTOR capable terminal node controller.
External links
- http://www.scs-ptc.com/pactor/pactor
- http://www.winlink.org/
- http://www.airmail2000.com/