LINK 11 Single Tone Modem
LESW
The single-tone waveform for Link-11 provides improved performance in HF Link-11 networks on a single sideband HF channel. Single-tone Link-11 uses an 8-phase modulated 1800-Hz tone. Adaptive equalization is used to demodulate the signal under the severe multipath conditions typical of HF propagation paths. Robust error detection and correction codes are used to provide enhanced message throughput.
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LINK 14 LINK 14
BEAVER
LINK 14 is a broadcast HF teletype link for maritime units designed to transfer surveillance information from ships with a tactical data processing capability to non-tactical data processing ships. The design of the teletype transmission allows reception over very long ranges. Link 14 provides the capability to broadcast picture compilation and status information for use in units unable to receive Link 11 transmissions either direct or via an interface, e.g.
non-Tactical Data System (TDS) units. The Link can be either HF, VHF or UHF dependent on unit-communication fits. More than one Link 14 net, with or without separate transmitting units, may be set up if desired, e.g. to split air and surface/sub-surface data. However, some units will be limited by communications fits in their capability to receive two nets. Few units will have the capability to transmit on two separate Link 14 channels at the same time. Selection of the Link 14 transmitting unit will depend on force disposition stationing of non-TDS units, Link 14 frequency, etc.
Each nation within NATO has its own Link 14 transmission formats which are promulgated in ADatP-14. Message protocol is defined in STANAG 5514.
Typical spectrum of a LINK 14 signal Typical spectrum of a LINK 14 signal
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LINK 16 LINK 16
TADIL J, MIDS, JTIDS
Multi-functional Information Distribution System - MIDS Joint Tactical Information Distribution System - JTIDS
MIDS/JTIDS is a high capacity, ECM-resistant communications link designed for all services (air, surface and land) and all platform types, i.e. for C2 and non-C2 units. The requirement for high capacity constrained the link to a UHF solution, thereby limiting the range of the system to direct LOS, but uses relay techniques designed into the system to achieve BLOS performance.
The term MIDS was used to define NATO's requirement for an ECM resistant information distribution system, that was already defined by the US as JTIDS.
MIDS/JTIDS supports three message standards: Link 16, IJMS and Variable Message Format (VMF).
MIDS/JTIDS uses a Time Division Multiple Access (TDMA) architecture. An enhancement using a distributed TDMA architecture was also under development to provide a further increase in capacity but development was cancelled in the mid-1980s. Activities are being undertaken to examine other higher bandwidth options whilst retaining the basic MIDS/JTIDS waveform.
Link 16 (also known as TADIL J in the US) has been designed to optimise the use of the MIDS/JTIDS architecture. Link 16 has been developed to meet the information exchange requirements of all tactical units, supporting the exchange of surveillance data, EW data, mission tasking, weapons assignment s and control data. The Link 16 message standard uses J-series messages and completely meets the requirements for C2 functionality and aircraft control. In addition Link 16 has been selected by the US and NATO as the main tactical data link for Theatre Missile Defence.
Numerous platforms have been or will be equipped with Link 16 (Airborne Surveillance and Intelligence Systems, C2 Systems, Fighter and Bomber Aircraft, SAM Systems, Ships, etc).
The UK has implemented Link 16 in its E-3D AWACS ; Tornado F3 fleet. Furthermore implementation is underway for RN ships and aircraft and other RAF C2 platforms and aircraft.
Message standards are defined in STANAG 5516 while standard operating procedures are laid down in ADatP 16.
Message Format - VMF
VMF is another Link 16 family protocol that uses Link 16 data elements to create variable length messages suitable for near real time data exchange in a bandwidth constrained combat environment. Earlier US Army VMF protocols contained ATDL-1 message elements.
The final and Joint Service version is still under development. VMF is intended to be filling the gap between what Link 16 & some other TDLs do and Message Text Formats.
Tactical Data Link - STDL: Link 16 via Satellite The Royal Navy investigated the use of the
Link 16 message standard on a satellite bearer to provide BLOS communications using Link
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LINK 22 LINK 22
NILE (NATO Improved Link Eleven)
NATO has designed a new data link, Link 22, which uses Link 16 elements in a TDMA architecture using either fixed frequency or frequency agile waveforms in the UHF (225- 400 MHz) and HF (3-30 MHz) bands. This programme was initially known as NILE (NATO Improved Link Eleven) and this name has been retained to some extent because the participants are called NILE Units; or NU’s. It is intended that Link 22 will eventually replace Link 11 and will provide secure, ECM-resistant data communications for BLOS operations.
The messages are defined in STANAG 5522 and are known as F-series messages. The messages are a mixture of completely new messages and messages in which Link 16 messages have been embedded without modification.
The aim is to use the data processing systems and radio equipments that are already installed in the candidate platforms and for nations to procure the cryptographic equipment from the USA under bilateral agreements.
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Marconi 25-Tone Modem Marconi 25-Tone Modem
This system is using two groups of tones one with 13 and the other with 12 tones.
These groups are separated by a pilot tone.
Different modes are possible i.e. NON ECM and ECCM mode.
In case of the ECCM mode a preamble with a FSK sequence is transmitted in advance and the pilot tone is missing. This preamble is working with 48 Bd and 480 Hz shift.
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Mazielka Mazielka
Mazielka is very often heard with the system CROWD36. It is a selective calling system which can use 6 out of 13 different tones.
It is used to alarm a receiving station if a non scheduled transmission should take place.
Spectrum of Mazielka Spectrum of Mazielka
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MFSK 8 MFSK 8
MFSK 8 is a multi-tone mode which uses 32 tones. Each tone is modulated with a symbol rate of 15.625 Bd or 62.5 Bps and FEC ½.
The tones are 15.625 Hz apart and use an overall frequency range of 316 Hz.
Spectrum of a MFSK 8 signal Spectrum of a MFSK 8 signal
Technical Handbook for Radio Monitoring Technical Handbook for Radio Monitoring
MFSK 16 MFSK 16
MFSK 16 is a multi-tone mode. It uses 16 tones in a bandwidth of 316 Hz. Each tone is modulated with a symbol rate of 15.625 Bd and FEC ½.
The transmission is based on 16-FSK (sequential single tone FSK), with continuous phase (CPSK) tones.
Tone weighting will be such that the lowest audio tone represents zeros in all bits. The weighting will increase in gray-code as the tone frequency is increased. This technique provides the least Hamming distance between adjacent tones:
T
Toonnee WWeeiigghhtt ToTonnee WWeeiigghhtt 0 (lowest) 0000 8 1100
1 0001 9 1101
2 0011 10 1111
3 0010 11 1110
4 0110 12 1010
5 0111 13 1011
6 0101 14 1001
7 0100 15 (highest) 1000
Spectrum of a MFSK 16 signal Spectrum of a MFSK 16 signal
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