Troposphere Spread (also known as troposcatter ) is a method of communicating with microwave radio signals within sufficient distance - often up to 300 kilometers (190 miles), and subsequently depending on the terrain and climatic factors. This propagation method uses a tropospheric scattering phenomenon, in which radio waves at UHF and SHF frequencies are scattered randomly as they pass through the top layer of the troposphere. The radio signal is transmitted in a narrow beam directed just above the horizon toward the receiving station. When the signal passes through the troposphere, some energy is dispersed back to Earth, allowing the receiving station to pick up the signal.
Typically, signals within the microwave range are moving in a straight line, and so are limited to the line of sight applications, where the receiver can be 'viewed' by the transmitter. Distance of communication is limited by visual horizon up to about 30-40 miles (48-64 km). Troposcatter allows microwave communication beyond the horizon. It was developed in the 1950s and used for military communications until communications satellites replaced it in the 1970s.
Because the troposphere is turbulent and has a high proportion of moisture, the troposphere scatter radio signals are refracted and consequently only a fraction of the radio energy is collected by the receiving antenna. The transmission frequency of about 2 GHz is best suited for troposphere scattering systems because at this frequency the signal wavelength interacts well with the humid volatile area of ​​the troposphere, increasing the signal to the noise ratio.
Video Tropospheric scatter
Overview
Historically, dish dishes or high dish antennas are required for troposphere scattering systems because of very high propagation losses; only about one billion-billion (1 x 10 -12 ) of the transmit power is available at the receiver. The track was established at a distance of more than 1,000 km. They require antennas ranging from 9 meters to 36 meters and amplifiers ranging from 1 kW to 50 kW. It is an analog system capable of transmitting multiple voice channels.
The Troposcatter system has evolved over the years. With communications satellites used for long-distance communications, the troposcatter system is currently used at a shorter distance than the previous system, using smaller antennas and amplifiers, and has a much higher bandwidth capability. Typical distances are between 50 km and 250 km, although longer distances can be achieved depending on the climate, terrain, and data rate required. The typical antenna size ranges from 1.2 meters to 12 meters while typical reinforcement sizes range from 10W to 2 kW. Data rates over 20Mbit/s can be achieved with current technology.
The spread of the troposphere is a reasonably safe propagation method because the alignment of dishes is very important, making it very difficult to cut the signal, especially if it is transmitted in open water, making it very attractive to military users. The military system tends to be a 'thin line' trope - so called because only narrow 'bandwidth' information channels are carried on the tropo system; generally up to 32 analog channels (4kHz bandwidth). The modern military system is "Wideband" because they operate digital data channels 4-16 Mbit/s.
Civil troposcatter systems, such as North Sea's North Sea oil communications network (BT), require a higher capacity 'information' capacity than are available using HF (high-3 to 30 MHz) radio signals, before satellite technology becomes available. The BT system, based in Scousburgh on the Shetland Islands, Mormond Hill in Aberdeenshire and Row Brow near Scarborough, is capable of transmitting and receiving 156 analog and (4-kHz bandwidth) data channels and telephones to/from the North Sea oil production platform, division multiplexing (FDMX) to merge channels.
Due to the turbulence nature in the troposphere, the quadruple diversity propagation path is used to ensure 99.98% reliability of service, equating about 3 minutes of interruption due to propagation breaks per month. The quadruple space and polarization diversity system requires two separate dish antennas (spaced several meters apart) and two different polarized feed horns - one using vertical polarization, the other using horizontal polarization. This ensures that at least one signal path is open at a time. Signals from four different paths are combined in the receiver where the phase corrector is removed phase difference from each signal. The phase difference is caused by the different path lengths of each signal from the transmitter to the receiver. After the corrected phase, all four signals can be combined positively.
Maps Tropospheric scatter
communication network of tropospheric spreading
The phenomenon of the troposphere scatter has been used to build civil and military communications relations in a number of parts of the world, including: -
- High ACE
- NATO in Europe. BT (British Telecom)
- United Kingdom - Shetland to Mormond Hill
- German
- Torfhaus-Berlin, Clenze-Berlin during the Cold War
- Portugal Telecom
- Portugal - Serra de Nogueira to Artzamendi
- CNT (Canadian telecommunication company)
- Tsiigehtchic to Galena
- Hay River - Port Radium - Lady Franklin Point
- Cuba - Florida
- Guanabo to Florida City
- AT & amp; T Corporation
Project Office [1]
- Chatham, NC [2] - Buckingham, VA [3] - Charlottesville, VA - Leesburg, VA - Hagerstown, MD
- Texas Towers - Air defense radar.
- Texas Tower 2
- Georges Shoal, in waters as high as 56 feet (17 m), 110 miles (180 km) east of Cape Cod 41Ã, Â ° 44? N 67Ã, Â ° 47? W/41.733Ã, Â ° N 67.783Ã, Â ° W/41.733; -67,783, linked to North Truro, MA.
- Texas Tower 3
- Nantucket Shoals, in 80-foot (24 m) waters, 100 miles (160 km) south-east of Rhode Island 40Ã, Â ° 45? N 69 Â ° 19? W/40,75 Â ° N 69,317 Â ° W/40,75; -69.317, linked to Montauk AFB, Long Island, NY.
- Texas Tower 4
- Unnamed Shoal (Unofficial: Old Shaky), in water 185-feet (56 m), 84 miles (135 km) southeast of New York City 39Ã, Â ° 48? N 72Ã, Â ° 40? W (Crushed, with 28 killed, during a storm on January 15, 1961), linked to the highlands, the mainland station of NJ.
- Texas Tower 1
- Cashes Ledge (Latitude 42 Â ° 53'N., Length 68Ã, Â ° 57'W., 36 feet depth), 100 miles east of New Hampshire, not built.
- Texas Tower 5
- Brown's Bank (Lat 42e, Â ° 47'N., Length 65Ã, Â ° 37'W., 84 feet deep), 75 miles south of Nova Scotia, not built .
- Mid Canada Line
- A series of five stations (070, 060, 050, 415, 410) in Ontario and Quebec in the vicinity of Lower Hudson Bay.
- Pinetree Line, Pole Vault
- A series of fourteen stations providing communication to Eastern coastal radar stations from the US/Canada Pinetree line, running from N-31 Frobisher Bay, Baffin Island to St. John's, Newfoundland and Labrador.
- White Alice
- Military and civilian communication networks with seventy-one stations stretching on the west coast of Port Hardy, Vancouver Island in the north to Barter Island (BAR) and east to Shemya, Alaska (SYA) in the Aleutian Islands.
- DEW Training
- Training facilities for White Alice and the DEW tropo-scatter network, between Pecatonica, Illinois and Streator, Illinois.
- DEW Line
- Some tropo-scatter networks provide communications for broad air defense radar chains in the northern tip of Canada and the United States.
- NARS
- NATO air defense network stretching from RAF Fylingdales, via Mormond Hill, UK, Sornfelli (Faroe Islands), HÃÆ'¶fn, Iceland to Keflavik DYE-5, Rockville.
- ET-A, USAREUR
- US Army Network from RAF Fylingdales to a network in Germany and one station in France (Maison Fort).
- 486L, MEDCOM
- US Navy Network covering the Mediterranean coast of Europe from San Pablo, Spain west to Adana AFB, Turkey to the East, with headquarters in Ringstead in Surrey, England.
- Royal Air Force
Communications to British German Troops, running from Swingate in Kent to Lammersdorf in Germany.
- BARS
- A tropo-scatter network The Warsaw Pact stretches from near Rostok in DDR (Deutsches Democracy Republic), Czechoslovakia, Hungary, Poland, Soviet Union, Soviet Union, Soviet Union, Romania, and Bulgaria.
- SEVER
- The Soviet network stretches across the Soviet Union.
- India - USSR
- One part of Srinigar, Kashmir, India to Dangara, Tajikistan, USSR.
- Indian Air Force
- Parts of the Air Defense Network include major airbases, radar installations and missile sites in North and Central India. The network is being removed to be replaced with a more modern optical-based communication system. Peace Ruby, Spellout, Peace Net
- The air defense network established by the United States in pre-revolutionary Iran. Spellout builds radar and communications networks in northern Iran. Peace Ruby builds another air defense network in the south and the Peace network integrates the two networks.
- Bahrain - UAE
- Tropical scattering system linking Al Manamah, Bahrain to Dubai, United Arab Emirates.
- RAFO
- The tropo-scatter communication system that provides military communications to the former SOAF - Sultan of the Air Force of Oman, (now RAFO - Royal Air Force of Oman), across the Sultanate of Oman.
- RSAF
- The Royal Saudi Air Force's tropo deployment network connecting major air bases and population centers in Saudi Arabia.
- Yemen
- One system that connects Sana'a with Sa'dah.
- BACK PORCH and IWCS
- Two networks run by the United States linking military bases in Thailand and South Vietnam.
- Phil - Tai - Oki
The system that connects the Philippines with Taiwan.
- Japan Troposcatter Network
- Two networks connecting the Japanese island from North to South.
Tactical Communications System Troposcatter
As well as the permanent network outlined above, there are many tactical transport systems produced by several countries: -
- Soviet/Russian Troposcatter System
- MNIRTI R-423-1 Brig-1/R-423-2A Brig-2A/R-423-1KF
- MNIRTI R-444 Eshelon/R-444-7.5 Eshelon D
- MNIRTI R-420 Athlete-D
- NIRTI R-417 Baget/R-417S Baget S
- NPP Radiosvyaz R-412 A/B/F/S TORF
- MNIRTI R-410/R-410-5,5/R-410-7,5 Athletes/Albatros
- MNIRTI R-408/R-408M ​​â € <â €
- People's Republic of China (PRoC), People's Liberation Army (PLA) Troposcatter
- CETC TS-504 Troposcatter Communications System
- CETC TS-510/GS-510 Troposcatter Communications System
- Western Troposcatter System
- AN/TRC-97 Troposcatter Communications System
- AN/TRC-170 Troposphere Deploy Microwave Radio Terminal
- AN/GRC-201 Troposcatter Communications System
The US Army and Air Force use a tactical tropospheric dispersal system developed by Raytheon for remote communications. This system has two configurations, the original "heavy tropo", and the newer "light tropo" configuration. The system provides four multiplex group channels and trunk encryption, and 16 or 32 local analog phone extensions. The US Marine Corps also uses the same device, albeit an older version.
See also
- Radio propagation
- Non-view-sight lines
- Microwave
- High ACE - Era of Cold War NATO European Tropospheric Network
- White Alice Communications System - The cold war era of Alaska troposphere communication links
- White Alice Communications System site listing
- TV-FM DX
- List of DEW Path Sites
- Away of the Early Warning Line
References
External links
- FS-1037C definition of the troposphere scatter
- Russia's troposphere relay communication network
- communication network map of Troposcatter
- Jane's AN/TRC-170 (v)
- Australia Air Air Tropospheric Distribution Communication System
- Communications Troposphere Spreading - important stuff
- Short film STAFF FILM REPORT 66-19A (1966) is available for free download on the Internet Archive
Source of the article : Wikipedia
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