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Aviation History
1953
1953 - 1258.PDF
414 RADIO AT FARNBOROUGH . . . while the Ultra uses pulse transmission and, in conjunction with the Rebecca-type search equipment specially developed, pro vides Sarah service—Search and Rescue and homing. This has t been very successfully demonstrated to home and overseas military authorities; and the lightweight Sarah equipment would prob ably have better range, and be easier to use, than the clumsy M.F. radio sets at present used for dinghy radio. The saving in weight of the dinghy radio sets would itself be an important point. The aircraft radio sets, and the air-to-ground communication services, are an important part of aviation radio, but only a part. The fixed radio services (point-to-point), for traffic control and airline operational messages, are equally important, and provide a service equally useful to every class of flyer. The volume of messages to be handled between busy airports is very large, and can be dealt with only by teleprinter, of either line or radio types, so the use of radio teleprinter equipments is slowly being extended—i.e., as quickly as possible with funds available. Radio-teleprinter transmitters and receivers are, essen tially, high grade H.F. sets with special adaptors, and in order to provide a regular reliable service are usually operated in parallel, spaced apart, to reduce the effects of fadings. Radio teleprinter terminal equipments were being shown by Redifon and Plessey, and the Redifon terminal was shown in operation, with an Italian teleprinter machine: surely a British teleprinter could have been used for the S.B.A.C. Show? Radio transmitters and receivers suitable for radio teleprinter operation are also made by Marconi and ST. and C, but were not on show. The ground end of ground-to-air communications is served by several manufacturers with regard to V.H.F., but only one—Redi fon—showed a ground station for H.F. R/T., with provision for four receivers in use on different frequencies, and a spare in the same rack, ready for use. The receivers were for fixed-frequency work, and a control unit for the ground H.F. R/T. transmitters was mounted alongside, the whole arrangement designed—in co-op eration with International Aeradio—for very convenient working. Similar receivers, for fixed-frequency working on H.F. or V.H.F. are made by several other firms, but were shown as separate individual receivers, along with their transmitters. V.H.F. trans mitters for air traffic control are usually of about 50 watts power, and typical sets were being shown by Burndept, Pye, and Redifon; others were described in literature by Marconi, S.T. and C, and Plessey. There were three exhibits of radar sets for providing assistance with airfield control. The Ekco unit has a manually-operated V.H.F. D/F. mounted integrally with the radar scanner, so that the taking of a bearing points the scanner at the aircraft. This ensures that bearing and distance are obtained at the same time. The equipment is mounted in a van, to be easily transportable, and is built especially for one-man operation. It can provide very use ful assistance in poor weather, but, of course, cannot handle a lot of aircraft, so is essentially for use at airports where traffic is fight. The other two radar exhibits were the Cossor and the Decca, and both were shown in use, though without the automatic V.H.F. D/F. which is a very desirable associated equipment. The radar units have a restricted range—25 miles maximum on the models shown —for airfield control; but widiin this range they provide a sharply defined picture, with very good accuracy—to a few feet at the shortest range. The Decca equipment has two similar C.R.T. units, and two transmitter units, which can be interchanged by switching in case of breakdown of either unit, thereby improving the reliability of the service. Both makes of radar are mounted in vans, and are readily transportable. To sum up, there was radio and radar equipment exhibited, on one stand or another, which will meet all the foreseeable needs of civil aviation, but some of it is not yet on the market. Production of competitive British equipment must be strongly urged. The display of light V.H.F. sets, for private owners and short distance charter work, is very good and there is a choice of navigation aids, to meet the most exacting demands of accuracy. Ground equip ment of all kinds is available, M.F., H.F., V.H.F., for telephone, telegraph and teleprinter working and of every power likely to be needed, to satisfy the most exacting customer. A Dutch visitor said to me, "Yes, it is good. Perhaps we need not spend so many dollars now." J.M. ROUND THE RADIO STANDS Burndept, Ltd., West Street, Erith, Kent, were showing a light weight single-channel V.H.F. transmitter/receiver which has been adopted by the R.A.F. as an emergency equipment for jet fighters. The set weighs 9 lb and gives 1£ watts output from a 24-volt supply. It is normally set up on 121.5 mc/s, but is capable of working on any frequency between 117-128 mc/s. A 24-volt 4 a.h. battery is available as a power source for this equipment, and should drive it for about two hours. The set should be quite suitable for use on a glider, where lightness is essential. The company were also showing their air-sea rescue beacon which is designed to be carried in a Mae West. It works on 121.5 mc/s and can be used for two-way radio telephone as well as beacon transmissions. The FLIGHT very small battery which energizes this equipment weighs 2 lb and will drive it as a beacon for six hours. The Burndept 10-watt V.H.F. trans mitter type BE.221 for ground-to-air communication and an associated receiver are also on show. These equipments have been built to an M.C.A. specification for airport control purposes. Ekco Electronics, Ltd., Ekco Works, Southend-on-Sea, Essex, were exhibiting their aerial coupling unit. This is designed to work with existing H.F. radio transmitters for aircraft and to transfer the output energy from the transmitter into the skin of the aircraft, so as to utilize the skin as an aerial. The model shown on the stand uses a four-turn coil as an inductive coupling, but the company are also working on H.F. slots for the same purpose. The coupling unit has its own tuning and matching device so that it will work over the whole of the frequency range, and it is claimed that this system is not less efficient as a radiator than the conventional wire aerials. The coupling unit is completely enclosed and presents no drag at all. The company were also showing a V.H.F. equipment suitable for the intermediate class of aircraft. It can be set up so as to work on either 11 or 22 independent channels in the V.H.F. band. It weighs 16 lb and has a power output of 1 watt with provision for working either from a 12-volt or 24-volt supply. The E. K. Cole approach-aid equipment was also on show. It provides a simple aid which can be operated by one man, combining V.H.F. D/F. with radar indication of aircraft height and distance. It is not a substitute for G.C.A., but is a useful aid at airfields which do not carry a lot of traffic. The Ekco airborne search radar equipment is also on show, as fitted to the R.C.A.F. Comets. Cossor Radar, Ltd., Cossor House, Highbury Grove, London, N.5, were showing a set of Gee Mark III navigational equipment. This is very much smaller, lighter and easier to handle than the Gee Mark II. There was a working demonstration of the Cossor airfield radar, which gives very good definition and would be a most useful aid to air traffic control in conditions of bad visibility. For use as a talk-down aid it would be used in conjunction with a V.H.F. D/F. Decca Navigator Co., Ltd., 1-3, Brixton Road, London, S.W.9. The novelty on the Decca stand was the lightweight Flight Log. The Mark VII receiver and the Mark 01 Flight Log were shown working from a simulator and the Mark VI Z r.igh-accuracy receiver was also on show. It is capable of working from any of the nine Decca chains. The Dectra system for long-range air navigation was explained in a leaflet and demonstrated on a map with representation of a track across the South Atlantic Ocean. The Decca type 424 airfield control radar was demonstrated in operation as a mobile unit. It is designed to be used in conjunction with the S.T. and C. V.H.F. D/F. an combines high accuracy with transportability. Marconi's Wireless Telegraph Co., Ltd., Marconi House, Chelmsford, Essex, were showing some of their own equipment and some made by their Australian associate, Amalgamated Wireless (Aus tralasia), Ltd. There is the 120-watt H.F. equipment, AD.107B/114, providing 20 frequencies for transmit and 30 for receive, and designed as a high-power R/T. version of the AD. 107. Transmitter and receiver together weigh about 125 lb. It is at present being fitted in B.O.A.C.'s Argonauts and Comets. There is also the A.W.A. nine-channel HAC-1 transmitter/receiver with 50-75 watts output on R/T. and weighing 65 lb, and the HAC-2 120-frequency crystal-controlled receiver,weighing 38 lb. This receiver has been designed for long-distance radio-telephone working, with pilot control. On V.H.F. there is the Marconi AD. 115 140-channel transmitter-receiver, with 15 watts output and weighing 33 lb with its remote controller, capable of working in any frequency between 118 mc/s and 132 mc/s; and at the other extreme, die A.W.A. Airmite V.H.F. transceiver, with three transmit frequencies, a tunable receiver, and provision for intercom—all in a set weighing only 12 lb, and with a range of up to 50 miles. The latest version of the very successful Marconi A.D.F., die AD.7092C, was demonstrated, as fitted with recessed loop aerials on Comets for B.O.A.C. and foreign airlines. There was also an AD.200 V.H.F. direction finder for ground use, as supplied to many overseas governments and in successful operation in many localities. The AD.94 tunable receiver is suitable for M.F. and H.F. and gives high discrimination and exceptional stability, but is built only for direct control. The A.W.A. 200 mc/s D.M.E. system, which is in service along the Australian airways, was described in a booklet, and there was a small scale model of a V.O.R. ground station, and a model of an aircraft radio installation using only Marconi equipment. On another line there was an air traffic control desk, designed and built in co-operation with International Aeradio, Ltd., which is an excellent example of a good tool for a good job. Ground transmitters— apart from the V.O.R. model—were not on show, but the company makes an extensive range of them, and can supply one for almost every need. McMichael Radio, Ltd., Wexham Road, Slough Bucks, had a selection of instruments on show, including their radio interference suppressors. These will find application especially on older aircraft— ignition interference does not seem to be any problem on modern types. Milliard, Ltd., Century House, Shaftesbury Avenue, W.C.2, were displaying radar-sonde and radar wind sets, chiefly of interest to the practising meteorologist. A radar theodolite measures wind speed and direction, and the radar-sonde transmits temperature, pressure and humidity at various heights up to 100,000ft, all these being recorded automatically in ground equipment. The company also builds H.F. and V.H.F. communications equipment, but none of these was on show Murphy Radio, Ltd., Welwyn Garden City, Herts, were showing their lightweight V.H.F. set for aircraft, with a choice of three control units, to give either five frequencies, 23 frequencies, or 36 frequencies. The transmitter/receiver unit is the same in each case, weighing 15 lb, with a power output of li watts, and capable of working from either 12 volts or 24 volts. The frequencies to be used are set up on the control unit and may be changed in flight in the case of the five-channel set. All three units can provide intercom service, and the facility of 36 V.H.F. channels for about 20 lb is very useful. Murphy 200 mc/s D.M.E. equipment was also
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