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Aviation History
1981
1981 - 3337.PDF
Telephonies proposes LCD radio-management system TELEPHONICS is proposing a digital radio and navigation frequency management unit for future airliners like the MDF-100, and for advanced Boeing 727s and 737s. Despite the set back when Airbus Industrie decided to stay with conventional separate (though digital) units for the A310, Telephonies hopes to become a sup plier for the Boeing 757, 767 and Air bus A310 and A320. Telephonies has flown its radio management system (RMS) on a Boeing 727 simulator, and a prototype has been demonstrated to several air lines in the USA and Europe. The company points to its radio-manage ment experience on the S-3A Viking and the SH-60B Seahawk, for which Telephonies has just won a produc tion contract. The RMS is a large unit akin to a flight management system, and uses liquid crystal displays (LCDs). The unit can tune active and standby fre quencies for dual VHF Corns and ADFs, and active frequencies for two HFs, a transponder, a VOR, and an ILS or DME. Course and runway head ing are displayed on the main LCD. A smaller LCD at bottom left is a scratch-pad display—the crewmember keys the desired frequency and then transfers it to the relevant line on the main display by pressing the adjacent button (see picture). The right-hand lower LCD is a mode dis play, on which the systems in use are announced after selection by the keys immediately below. Thus the crew has a display of all selected frequencies, below which the sets actually in use are annunciated. A typical installa tion would comprise two RMS control and display units. LCDs were chosen because of their low power and space requirements, and their low costs. Unfortunately, the type of LCD widely used in watches is not suitable because it is difficult to read from sharp angles, and is sus ceptible to high temperatures. Tele- phonics has thus gone for the guest- host (dichoic) LCD, which traps the liquid crystal between two glass plates which have a transparent con ducting coating. When current is applied, the crystals line up, as do the molecules of a black dye mixed with the liquid. The aligned dye molecules become transparent, and can be con trolled to give alphanumeric symbols. The dicnoic technique results in white figures on a black background, which is ideal for cockpits. The method is being used by General Elec tric for 757 and 767 engine displays. Telephonies says that there are no off-angle or temperature problems, and that it knows of no failure modes —except for the breaking of the glass or seal. One problem, which Telephonies feels is soluble, is that the dye may FLIGHT International, 24 October 1981 be susceptible to ultraviolet light. New dyes are under development, but there is some "greying" at present. Night time viewing is overcome by back lighting, which may be on continu ously, according to Telephonies. One aim for large LCDs is to be able to inject electrical signals into the display in serial form, rather like a data-bus. This would avoid the need for a separate pair of wires for each segment, which can be a snag with a large number of displays in a con fined space. Telephonies tells Flight that it has run a prototype display which uses a multiplexing technique. This applies current to a matrix surrounding the display area, and has been achieved by a method of combining the elec tronics (a chip) with the display hard ware. Naturally, the company is reti cent about the details, and it needs to do more proving, but the technique could make alphanumeric and even pictorial LCDs possible. Telephonies is certain that LCDs are the answer, rather than cathode ray tubes (CRTs), light-emitting diodes, or gas discharge displays. For example, an incandescent display costs about $30 a character, says Tele- phonics, whereas an LCD may be as little as $3 a character. CRTs are heavy and need a lot of power, while the emissions from other displays are a potential problem. The concept of radio management may not be high on an airline's list of procurement priorities, since it does not save fuel. But Telephonies is committed to developing a good system, and it says that pilot response is good. The claimed benefits are space and wiring savings for the manufacturer—the unit simply plugs into the data-bus—and lower work load and maintenance costs. First cost is comparable with con ventional digital systems, and older radios could be accommodated if analogue/digital converter modules were added. Telephonies also points out that its LCD technique is capable of colour presentation, and that it has a non-volatile memory. It claims a potential mean time between failures of 40,000hr. The RMU weighs in at less than 51b. Pulses... RCA Missile and Surface Radar has been awarded $4 million to help the FAA in its plans to up grade US ATC computers. The company will provide system en gineering and technical analysis. Current FAA plans call for re placement of 23 air-route traffic control centres with an advanced system, which would cope with ATC demands of the 1990s. MEL's Marec airborne reconnais sance radar system has been chosen by the Cameroon Govern ment for its Dornier 128-6 mari time patrol aircraft. The £300,000 contract calls for deliveries of the systems to begin next month. Plessey Radar has added to ATC facilities at Romania's Constanta airport, improving equipment which it installed in 1972. The im provements are necessary because of a tenfold increase in seasonal tourist traffic. They include mod ernisation of the AR-1 primary radar, addition of a Plessey Series 200 SSR, and replacement of the primary radar displays with ones able to handle aircraft labelling. Racal-Decca announces £2-8 mil lion worth of orders for its Doppler 80 airborne navigation system. Many of the units are for the Sultanate of Oman, and the appli cations include light transport air craft and helicopters. Monarch Airlines and Transbrasil Airlines have selected Bendix digital navigation receivers and RDR-4A colour weather radar for their Boeing 757s and 767s respec tively. The units include VOR, ILS, radio altimeter, DME, ADF, and transponder. Transbrasil has also chosen the Bendix VHF radio. 1245
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