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Aviation History
1960
1960 - 1985.PDF
FLIGHT, 16 September 1960 Standard Telephones QA 8 field test set with which complete functional checks can be made on airborne VOR/ILS equipment propagation difficulties. Ultimately such a system could be used intransatlantic flights for the automatic transmission of data such as height, position, identity, destination to air traffic control centres. A trans-mission system that could be simply installed and would make use of the existing HF transmitter in an aircraft making routine nights has hadto be used; so that the type of transmission used is not ideal and would be modified in an operational link. Previously, there has been no information on the reliability of suchdata links, although most plans for introducing automation into air traffic control assume it can be done. A piece of equipment which may have significance in this respect wasexhibited by Redifon. Their new GR410 transistorized single-sideband transmitter-receiver for 3-18Mc/s produces 100W p.e.p. with a d.c.power consumption of only 7W. Single-sideband data transmission would probably suffer less from fading than the present system ofdouble-sideband transmission. The GR410 is designed for mobile use but not specifically for aircraft; but it is reported that the UN areconsidering using the equipment for communication between aircraft and vehicles in die Congo. It seems inevitable that SSB will becomestandard for aircraft HF communication as bands become more congested. A radar tape recorder suitable for recording air traffic movementsfor retrospective analysis was shown by Decca Radar. An Ampex VR 1000B Videotape recorder has been modified by the addition of unitsbuilt from the Decca InterScan display system. Advantage over film projection techniques is gained in the more detailed and realistic displaymade possible by the greater dynamic range of the tape system. Data from single-beam surveillance radar can be accepted with a bandwidthof 20c/s to 3.6Mc/s, ±2db, together with speech in a bandwidth of 50c/s to lOkc/s. On a basis that the minimum usable signal is 6dbabove system noise, a linear useful dynamic range of at least 26db is available. A 14in reel of tape gives a playing time of 96min, makingthe equipment suitable for general training of air traffic controllers, investigation of transient "unwanted phenomena" on radar displays,and demonstrations of radar equipment. Radar simulators for training air traffic controllers were displayedby Redifon. Target simulation is carried out by desk consoles, each of which is capable of simulating two targets. As the "drivers" for the targets are recruited from unskilled personnel, much care has beentaken to make the simulator as easy to use as possible. In particular, much use has been made of push-buttons.A transistorised tape recorder suitable for monitoring ATC voice communications was shown by Thermionic Products. The equipmentcontinuously monitors all channels (20 on lin tape) to detect malfunc- tioning. If a fault appears on one channel it is automatically switchedout and the signal transferred to a standby channel. If a fault occurs on two channels a complete standby recorder is switched in. Another contribution for future ATC systems, the SSR4G Cossorsecondary radar scheme was shown complete in its pre-production form this year. The circuit principles demonstrated by the prototype designlast year are retained. It is noteworthy that a servo system slaves the remote secondary radar aerial to follow the primary radar aerial towithin ± i°, a 400c/s system being used to obtain quick response. Also looking ahead to future ATC systems, Standard Telephones andCables showed their PVT2 automatic DF triangulation system. Whereas the PVT1 system displays bearing indications by projectionof lines on a wall map, the new version provides a television display suitable for distribution to any number of monitoring screens. Bearingindications from various DF stations on individual cathode ray tubes are combined optically to provide a miniature triangulation displaywhich is viewed by a closed circuit television camera. There are facihties for plotting aircraft positions, identities, and tracks so thatthey appear on the television monitor display. Work on the extraction of bearing data in digital form is under way. STC also showed their STR-40 radio altimeter for the first time.This is a single-range instrument (500ft) designed for automatic landing systems. Displayed with it was the QA10 test set for this altimeter.If the altimeter shows a fault on operation of the confidence check switch in the aircraft, the main unit is removed and returned to thelaboratory, where it is plugged into the QA10. The test set is used for both checking and aligning the unit to the required accuracy. It is notyet in production. Other test sets displayed by the company included QA9 (ILS/VORtone generator for accurate setting up of equipment), and QA8 (portable transistorized test set for airborne ILS/VOR requirements). The latterunit achieves its coverage in the 300Mc/s band by addition of a 200Mc/s oscillator signal to a 130Mc/s signal. In general, civil equipment at theexhibition exhibited this upper frequency limit of about 200Mc/s for transistor operation. Some of the military equipment, particularly inthe telemetry field, gave the impression that transistors were being used there at still higher frequencies. It is generally felt that UHF transistorswill make their appearance in civil equipment in the near future. Ekco weather radar (E190), in keeping with the growing practice ofduplicating essential services in aircraft, can now be installed as a duplicate system. The equipment includes two transmitter/receiverunits and two indicator /control units operating from a single scanning unit in the nose of the aircraft, it being possible to mix units fromdifferent channels. The nose unit is basically similar to that of the E190 single system, but the servo motors have been duplicated and die RCcircuitry associated with the servos has been taken out and built into the back of the duplicated receiver/transmitter unit, in the new inter-lock compartment; the whole assembly becomes a long full ATR. The aerial unit is fitted with twin synchros to drive the independent timebases. Ferranti took some of the covers off Airpass I and Airpass II radar.Airpass II is a radar fire-control and bomb aiming system provided with additional faculties compared with Airpass I and developed as aprivate venture. Contour mapping, to assist in hill avoidance and to assist descents on to difficult airfields is included together with terrainclearance, or profile flying, facilities. A dead reckoning navigational computer is available for the equip-ment, equipped with push-button inputs. When pre-set co-ordinates of points on the aircraft's route are fed in by pushing the appropriatebutton the computer will indicate the range and bearing to the point. It will opsrate from Doppler, air data or an inertial platform and isintegrated into the radar display to present the range-bearing informa- tion as a deflection of the target spot or as a marker circle on the ground-mapping display. Inspection of the equipment shown indicates that many more transistors are used in Airpass II than in Airpass I. Particularly interesting is the new version of the pilot's hand controlfor the equipment. This is shaped for operation by the left hand only, conforming to its contours. Overall movement of the palm operatesa rate control of the target spot, instead of the positional type of control used in Airpass I. In addition, the hand control also manages to Left, the first Decca Omnitrac computer. Off-the-shelf com- ponents have been used and the memory drum is behind the front of the case. Right, the Cossor S-band power distribu- tion board with 32 components (described on page 472)
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