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Aviation History
1946
1946 - 2047.PDF
OCTOBER IOTH, 1946 FLIGHT CIVIL AVIATION NEWS present R/T or C/W communicationsystem used in civil aviation could be replaced by some automatic signallingsystem. For example, the language diffi- culties would be removed and therewould be an increase in the reliability and accuracy of air-to-ground communi-cation. A signalling system can never be as flexible with regard to informationthat is transmitted as a system using R/T or C/W morse; however, using asuitable code it is possible to pass sufficient information . for control andweather reports to cover normal require- ments. An automatic system under the nameof Impulse Signalling has already been constructed and was in fact used by theR.A.F. Fighter Command during the later stages of the war, but the numberof available characters was limited and the speed of transmission slow. A newsystem is being developed which over- comes to a degree some of these limita-tions. It works on the following principle: A signal consists of a constantnumber of double tone impulses, the first and last of which are double the length of the remainder. Within the spacesthus created are other double tones forming the units of intelli- gence of the signal. Each unit is arranged to position thecorresponding disc in an indicator unit so as to display the character through a fixed window and each disc has fortyeffective positions. Discs are selected in turn by sequence selection and the position of each disc is selected by directselection. By the reservation and suitable application of the intelligence carried in the first two spaces, any particular indi- B.E.A. GIRL : The new uniform to be used by B.E.A.'sstewardesses and traffic clerks which will be first seen at the Paris Exhibition. The colour is grey—as opposed to the more usual airline navy used in the B.O.A.C. design. TAKING SHAPE : The work on the first of the two Brabazon I's, or Bristol 167 pro-totypes, is prcgressing very rapidly—as this recent photograph shows. An immense amount of development work will be necessary on this and the second prototypebefore the 167 can be put into service ; its first flight will be merely the beginning. cator can be made to respond only to a particular combinationor call sign. The transmission equipment consists of a control unit incorporating a display of the outgoing message and amodulator unit. The message is sent by depressing keys on an illustrated keyboard; and acknowledgment is indicatedautomatically by a green light. A message received in corrupt form by an aircraft would not be acknowledged. The messagemay be sent to a single aircraft, or to any number simul- taneously. It is believed that a communication system couldbe developed enabling messages to be passed with greater speed and efficiency than could be achieved by R/T or morse, andwith greater reliability and accuracy of transmission. The principle of SCS.5I, blind approach and landing systemwhich was described briefly in Flight dated September 19th, has been adopted and improved by Pye, and an electronicmodulator on the 90 and 150 Mc/s frequencies has been substi- tuted for the mechanical modulator. The glide path antennadesign has also been improved, giving fewer minor lobes. It is well known that precipitation static interference is aserious menace to radio communication with aircraft, and even interferes occasionally with ground installations. Corona dis-charge into the atmosphere is the cause of the interference, and produces electrical noise which becomes coupled into theaerial circuit. When flying in dust storms or ice clouds, an aircraft could charge up to a potential of a million volts witha field gradient of several thousand volts per centimetre near the aerial. The aerials may now be insulated to prevent coronaforming, and comparative freedom from precipitation static doubles is achieved. The greater diameter of the aerial wiremay, however, cause icing trouble. Orb i.s the name given to a homing device which permitsselection on a dial of a desired direction of approach. An independent pointer indicates the correction necessary to findthat course. This system could be particularly useful in moun- tainous districts; . The new flying control tower at Farnborough contains aplotting table on which a constant watch is kept of the progress of all aircraft under control. Another interesting feature isihe Optical Angulator. An operator receives W/T. bearings from three different ground stations which when set on dialsare each displayed through a map of the area by beams of light radiating from the stations, and a fix is immediatelyprovided by the intersection. The occasion of these demonstrations was obviously notsuitable for an exhibition of other flying safety measures and devices, but it would be interesting to know about the develop-ments in flying instruments. A more reliable and more quickly responding artificial horizon would be a useful contributionto flying and to which radar i>might be applied. BREAK OF JOURNEYS BRITISH EUROPEAN AIRWAYS have announced thatpassengers will be permitted to break their journey at intermediate stops when holding through tickets. It is a pre- requisite, however, that passengers must state their require- Vo,
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