Multiple frequency-shift keying
Encyclopedia
Multiple frequency-shift keying (MFSK) is a variation of frequency-shift keying
(FSK) that uses more than two frequencies. http://sharon.esrac.ele.tue.nl/mirrors/zl1bpu/ MFSK is a form of M-ary orthogonal modulation, where each symbol consists of one element from an alphabet of orthogonal waveforms. M, the size of the alphabet, is usually a power of two so that each symbol represents log2M bits.
for a given probability of error decreases as M increases without the need for multisymbol coherent detection.
In fact, as M approaches infinity the required Eb/N0 ratio decreases asymptotically to the Shannon limit of -1.6 dB
. However this decrease is slow with increasing M, and large values are impractical because of the exponential increase in required bandwidth. Typical values in practice range from 4 to 64, and MFSK is combined with another forward error correction
scheme to provide additional (systematic) coding gain.
(DTMF), which is used in touch tone phones and the Multi-frequency
trunk signals used in Twentieth Century telephone exchanges.
These signals are distinctive when received aurally. Their main feature is a rapid succession of tones with almost musical quality.
communications:
Piccolo was the original MFSK mode, developed for British government communications by Harold Robins, Donald Bailey and Denis Ralphs of the Diplomatic Wireless Service (DWS), a branch of the Foreign and Commonwealth Office. It was first used in 1962 and presented to the IEE
in 1963. The current specification "Piccolo Mark IV" is still in limited use by the UK government, mainly for point-to-point military radio communications.
Coquelet is a similar modulation system developed by the French Government for similar applications.
MFSK8 and MFSK16 were developed by Murray Greenman, ZL1BPU for amateur radio communications on HF. Olivia MFSK is also an amateur radio mode. Greenman has also developed DominoF and DominoEX for NVIS
radio communications on the lower HF frequencies (1.8-7.3 MHz). http://sharon.esrac.ele.tue.nl/mirrors/zl1bpu/DOMINO/Index.htm
ALE (Automatic link establishment
) is a protocol developed by the USA military and used mainly as an automatic signalling system between radios. It is used extensively for military and government communications worldwide and by radio amateurs.
"CIS-36 MFSK" or "CROWD-36" is the western designation of a system similar to Piccolo developed in the former Soviet Union for military communications.
"XPA" and "XPA2" are ENIGMA-2000 designations for polytonic tranismissions, reportedly originating from Russian Intelligence and Foreign Ministry stations. Recently the system was also described as "MFSK-20".
FSK441, JT6M and JT65 are parts of the WSJT
family or radio modulation systems, developed by Joe Taylor, K1JT, for long distance amateur radio VHF communications under marginal propagation conditions. These specialized MFSK modulation systems are used over troposcattering, EME (earth-moon-earth) and meteoscattering radio paths.
DTMF was initially developed for telephone line signaling. It is frequently used for telecommand (remote control) applications over VHF and UHF voice channels.
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...
(FSK) that uses more than two frequencies. http://sharon.esrac.ele.tue.nl/mirrors/zl1bpu/ MFSK is a form of M-ary orthogonal modulation, where each symbol consists of one element from an alphabet of orthogonal waveforms. M, the size of the alphabet, is usually a power of two so that each symbol represents log2M bits.
- M is usually between 2 and 64
- Error Correction is generally also used
How it works
Like other M-ary orthogonal schemes, the required Eb/N0 ratiofor a given probability of error decreases as M increases without the need for multisymbol coherent detection.
In fact, as M approaches infinity the required Eb/N0 ratio decreases asymptotically to the Shannon limit of -1.6 dB
Decibel
The decibel is a logarithmic unit that indicates the ratio of a physical quantity relative to a specified or implied reference level. A ratio in decibels is ten times the logarithm to base 10 of the ratio of two power quantities...
. However this decrease is slow with increasing M, and large values are impractical because of the exponential increase in required bandwidth. Typical values in practice range from 4 to 64, and MFSK is combined with another forward error correction
Forward error correction
In telecommunication, information theory, and coding theory, forward error correction or channel coding is a technique used for controlling errors in data transmission over unreliable or noisy communication channels....
scheme to provide additional (systematic) coding gain.
Types
Defined examples of a multiple frequency-shift keying system include dual-tone multi-frequencyDual-tone multi-frequency
Dual-tone multi-frequency signaling is used for telecommunication signaling over analog telephone lines in the voice-frequency band between telephone handsets and other communications devices and the switching center. The version of DTMF that is used in push-button telephones for tone dialing is...
(DTMF), which is used in touch tone phones and the Multi-frequency
Multi-frequency
In telephony, multi-frequency signaling is an outdated, in-band signaling technique. Numbers were represented in a two-out-of-five code for transmission from a multi-frequency sender, to be received by a multi-frequency receiver in a distant telephone exchange...
trunk signals used in Twentieth Century telephone exchanges.
These signals are distinctive when received aurally. Their main feature is a rapid succession of tones with almost musical quality.
HF communications
MFSK or "polytone" modes used for shortwaveShortwave
Shortwave radio refers to the upper MF and all of the HF portion of the radio spectrum, between 1,800–30,000 kHz. Shortwave radio received its name because the wavelengths in this band are shorter than 200 m which marked the original upper limit of the medium frequency band first used...
communications:
- MFSK8
- MFSK16
- Olivia MFSKOlivia MFSKOlivia MFSK is an amateur radioteletype protocol designed to work in difficult conditions on shortwave bands. The signal can still be properly copied when it is buried 10 dB below the noise floor...
- Coquelet
- Piccolo
- ALEAutomatic link establishmentAutomatic Link Establishment, commonly known as ALE, is the worldwide de facto standard for digitally initiating and sustaining HF radio communications. ALE is a feature in an HF communications radio transceiver system, that enables the radio station to make contact, or initiate a circuit, between...
(MIL-STD 188-141) - DominoF
- DominoEX
- THROB
- CIS-36 MFSK or CROWD-36
- XPA, XPA2
Piccolo was the original MFSK mode, developed for British government communications by Harold Robins, Donald Bailey and Denis Ralphs of the Diplomatic Wireless Service (DWS), a branch of the Foreign and Commonwealth Office. It was first used in 1962 and presented to the IEE
Institution of Electrical Engineers
The Institution of Electrical Engineers was a British professional organisation of electronics, electrical, manufacturing, and Information Technology professionals, especially electrical engineers. The I.E.E...
in 1963. The current specification "Piccolo Mark IV" is still in limited use by the UK government, mainly for point-to-point military radio communications.
Coquelet is a similar modulation system developed by the French Government for similar applications.
MFSK8 and MFSK16 were developed by Murray Greenman, ZL1BPU for amateur radio communications on HF. Olivia MFSK is also an amateur radio mode. Greenman has also developed DominoF and DominoEX for NVIS
Near Vertical Incidence Skywave
Near Vertical Incidence Skywave, or NVIS, is a radio-wave propagation method that provides usable signals in the range between groundwave and skywave distances . It is used mainly for military and paramilitary communications and by radio amateurs...
radio communications on the lower HF frequencies (1.8-7.3 MHz). http://sharon.esrac.ele.tue.nl/mirrors/zl1bpu/DOMINO/Index.htm
ALE (Automatic link establishment
Automatic link establishment
Automatic Link Establishment, commonly known as ALE, is the worldwide de facto standard for digitally initiating and sustaining HF radio communications. ALE is a feature in an HF communications radio transceiver system, that enables the radio station to make contact, or initiate a circuit, between...
) is a protocol developed by the USA military and used mainly as an automatic signalling system between radios. It is used extensively for military and government communications worldwide and by radio amateurs.
"CIS-36 MFSK" or "CROWD-36" is the western designation of a system similar to Piccolo developed in the former Soviet Union for military communications.
"XPA" and "XPA2" are ENIGMA-2000 designations for polytonic tranismissions, reportedly originating from Russian Intelligence and Foreign Ministry stations. Recently the system was also described as "MFSK-20".
VHF & UHF communications
MFSK modes used for VHF, UHF communications:- DTMF
- FSK441
- JT6M
- JT65
FSK441, JT6M and JT65 are parts of the WSJT
WSJT (Amateur radio software)
WSJT is a computer program used for weak-signal radio communication between amateur radio operators. The program was initially written by Joe Taylor, K1JT, but is now open source and is developed by a small team...
family or radio modulation systems, developed by Joe Taylor, K1JT, for long distance amateur radio VHF communications under marginal propagation conditions. These specialized MFSK modulation systems are used over troposcattering, EME (earth-moon-earth) and meteoscattering radio paths.
DTMF was initially developed for telephone line signaling. It is frequently used for telecommand (remote control) applications over VHF and UHF voice channels.
See also
- RadioteletypeRadioteletypeRadioteletype 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...
- frequency-hopping spread spectrumFrequency-hopping spread spectrumFrequency-hopping spread spectrum is a method of transmitting radio signals by rapidly switching a carrier among many frequency channels, using a pseudorandom sequence known to both transmitter and receiver...
also uses many different frequencies, where each symbol uses only one frequency. - DTMF
- Olivia MFSKOlivia MFSKOlivia MFSK is an amateur radioteletype protocol designed to work in difficult conditions on shortwave bands. The signal can still be properly copied when it is buried 10 dB below the noise floor...
- ALEAutomatic link establishmentAutomatic Link Establishment, commonly known as ALE, is the worldwide de facto standard for digitally initiating and sustaining HF radio communications. ALE is a feature in an HF communications radio transceiver system, that enables the radio station to make contact, or initiate a circuit, between...
(MIL-STD 188-141) - WSJTWSJT (Amateur radio software)WSJT is a computer program used for weak-signal radio communication between amateur radio operators. The program was initially written by Joe Taylor, K1JT, but is now open source and is developed by a small team...