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Aviation History
1960
1960 - 2917.PDF
FLIGHT, 9 December 1960 917 and tracking symbols and facilities for targethandover to parallel viewing units. Decca Radar Ltd offer the Type D.A.S.R.lS-band primary surveillance equipment, giving gap-free coverage to ranges of over 100n.m. and heights above 40,000ft. It features a back-to-back (cosec; and linear) aerial system,variable circular polarization to eliminate pre- cipitation returns, and a form of permanentecho suppression known as Air Target Indica- tion. InterScan displays permit superimposi-tion of tracking and map information. More than 100 orders have now been re-ceived for the Decca airfield control radar Type 424, a low-cost static, air-transportableor mobile landing aid which provides all- round surveillance for aircraft in the local areaas well as precision azimuth information for final talk-down. Variable polarization reducesprecipitation echoes. The fully controllable display incorporates range markers, bearingcursor and off-centre controls. Transmission is at 9,320-9,500Mc/s and max power is 30kW. Decca also manufacture ASMI (airfield sur-face movement indicator) radar for controlling and observing movement on the ground inpoor visibility. Range is eight miles, trans- mitting in Q-band at 15kW. Marconi's Wireless Telegraph Co Ltd offera wide range of high-performance radars m the 10, 25 and 50cm bands, each with its ownadvantages. In the 10cm (S-band) category, the Type S.306 offers good discrimination be-tween close targets, freedom from siting diffi- culties, and unattended operation, with fullremote control. A triple-pulse MTI perman- ent echo-cancellation system is fitted. The veryhigh peak-power of 3MW is a feature of this equipment, which operates on frequenciesbetween 2,700 and 3,300Mc/s. For airports where the aerial must bemounted on the control tower, the Type S.263/1 is available in the 10cm range, withlightweight aerial capable of operation in wind speeds up to 70 m.p.h. Peak power is over800kW; frequency 2,960-3,040Mc/s. One of the latest Marconi long-range sur-veillance radars is the Type S.247, comprising two high-power (2i-3MW) transmitters, oneat 10cm and one at 25cm, feeding a combined back-to-back aerial system. Together they givecontinuous cover on targets up to 75,000ft, with provision for MTI, remote control, etc. Type S.255 utilizes the 25cm (L-band) sys-tem only, to give cover on small aircraft out to 200 miles. It is less affected by cloud andrain clutter than 10cm equipment, offers more efficient MTI characteristics and is capableof considerably better overall performance. Peak power is 2.5MW. Marconi's 50cm radar sets combine all thefeatures of the 10 and 25cm types, with out- standing reliability and freedom from theeffects of weather and permanent echoes. The Type S.264A is a 500kW system developedfrom the equipment which has been used for some years at London Airport. The S.264A/Hhas a modified aerial providing increased vertical coverage at the expense of maximumrange. Most recent of the series is the S.307, which possesses all the qualities of the S.264Abut has improved definition and increased maximum range. All these radars are crystal-controlled and can be used simultaneously on long-range surveillance or close control ofaircraft within the terminal area, using either fixed-coil or moving-coil PPI displays andvideo mapping if required. Display units developed for use with these installations offerthe latest facilities for target marking, track- ing and handover between consoles. Other Marconi radar sets range from theType S.261 mobile 50cm radar to the 3cm SNW.40 series, which have a range of up to45 n.m., with a peak power of 40-50kW and frequency of 9,360-9,460Mc/s. A recent Marconi development is a para-metric amplifier for use with the range of 50cm radars. It incorporates a fully coherentpump frequency which is crystal-locked to the radar and to a fully coherent MTI—the onlyone of its type in the world. The tube itself and its solenoid are manufactured by theEnglish Electric Valve Co. Aerial mountings and turning gear for sur-veillance radar are among the products of John Curran Ltd. Height-rinding Radar From Marconi comes the Type S.239800k W 10cm height-finder, designed to oper- ate in conjunction with long-range surveillanceradars and with an accuracy of + 500ft at 50 n.m. Its parabolic reflector aerial "nods" tocover a vertical angle between — 1° and +25" ten times per minute, and transmits on a fixedfrequency in the 2,960-3,040Mc/s band. It is controlled from the elevation/scan displayconsole. The Type S.244 is more powerful, with anaccuracy of + 1,700ft at 150 n.m. It has a peak output of 3MW in the 2,7qO-2,9OOMc/sband and is capable of determining the abso- lute height of an aircraft above the ground orthe relative heights of two aircraft. It can also operate as a volumetric radar, providing bothheight and plan position information. Another highly-accurate long-range height-finder is the Decca HF.200. Like the Marconi S.244, this incorporates automatic limitationof the angle of nod when dealing with long- range targets, to avoid scanning useless air-space at high angles of elevation. Precision Approach Systems Probably the most important guidance ele-ment in precision approach is ILS; and its importance is likely to increase as automaticlanding systems are introduced. Already in service for some time is the ILS manufacturedby Pye Telecommunications Ltd and in world- wide service as a civil and military approachaid. It utilizes a uni-directional localizer and has full monitoring, self-correction and stand-by equipment in accordance with ICAO speci- fications. Marker beacons are usually posi-tioned some five miles and 3,500ft from the threshold and at the threshold itself. A more recent installation is the STAN7/8/9 ILS with localizer, glide-slope and marker beacon transmitters, now being pro-duced by Standard Telephones & Cables Ltd for the MoA. It includes directional andclearance localizer aerials, which reduce siting problems. Many components, including thefail-safe monitors, are transistorized and a newly developed mechanical modulation sys-tem gives greater stability and freedom from phase distortion. Both localizer and glide-pathtransmitters are fully monitored and automatic five-second change-over are provided betweenmain and standby transmitters. Standard Telephones' ILS has been installed at Lon-don Airport and is on order for several other major airports in Britain and abroad. A system which may possibly be used inconjunction with ILS for automatic landing is the Leader Cable, for which the airborne andground-based units have been produced by Murphy Radio Ltd. The cables are laidparallel with the runway centreline extended some 5,000ft beyond the end of the runway.Leader Cable at present forms part of trie military Autoland system. Simplest of the precision approach radarsand already proven in service at Southend Airport is the Ekco Electronics Ltd TypeCE71 approach aid, which combines a manu- ally-aimed 3cm ranging radar with a VHF DFsystem. Suitable for either static or mobile installation, it can be operated by one man andprovides talkdown facilities for every type of aircraft. Operating from a.c. mains, theequipment has a power output of lOkW. The A-scope display is calibrated in two ranges,0-4 and 0-16 n.m., and an azimuth cursor can be used for directing off-set final approaches. Precision Approach Radar SLA.3/B2,manufactured by Standard Telephones & Cables Ltd, provides the controller with three-dimensional information on approaching air- craft on twin azimuth/range and elevation/range cathode-ray tubes. Two 50kW 3cm transmitters, installed in an unattendedvehicle, radiate a pulsed fan beam which sweeps an area of approximately three miles byone mile at a range of ten miles. After an air- craft has been directed into this area, it can betalked down by GCA procedure. Installations can be fixed or turntable-mounted to coverseveral runways. Airports at which SLA.3/B2 radar is in use include Hong Kong and Wel-lington, New Zealand, where the runways extend out to sea and are approached overdifficult terrain. Direction-finding and Beacon Equipment Ekco Electronics Ltd offer at an exception-ally low price (approximately £2,000) the CE.178 CRDF equipment with a range ofabout 100 miles for an aircraft flying at 10,000ft. and radiating 5W. Bearing indication Pump frequency multiplier and amplifier of the Marconi parametric amplifier for surveil- lance radars Cossor CR.353 meteorological radar (artist's impression) is given, with a maximum error of + 1.5 deg,by a single radial line on a 6in cathode-ray tube, which can be positioned up to 2 n.m.from the 250 r.p.m. Adcock aerial. Frequency range is 100-156Mc/s.Marconi produce a range of DF equipment. Types AD.210A and B provide visual, auto-matically sensed bearing indication on four channels simultaneously. They operate in the100-]56Mc/s band and can be integrated with ground-to-air communications schemesto provide combined DF and voice facilities. In addition, airfield control radar of suitabletype can be fed with DF intelligence for identification purposes. Five crystal-controlledfrequencies are provided for each channel. Type AD.210C is a simple low-cost single-channel model. In all cases the master and slave display units can be sited remotely. Type AD.200 is a two-channel equipmentoperating in the 118-132Mc/s band, with local or remote (up to 30 miles) instantaneous pre-sentation on an 8in diameter meter indicator. It is suitable for fixer or homer stations andwill provide VHF DF identification for airfield control radar. An automatic fixer equipmentis available for use with the AD.200 and AD.210 series, giving direct presentation of anaircraft fix on a 17in cathode-ray tube, with a superimposed translucent map of the controlarea and controllable offset bearing-and- distance trace. Marconi also produce the Type DFg26/4HF DF equipment with twin channels and fre- quency range of 1.5-21Mc/s in four bands.Bearing presentation can be by spinning gonio- meter or cathode-ray oscilloscope. The TypeDFg29 is a manually operated HF DF instal- lation which can be mobile for rapid position-ing and can operate where earth conductivity is so poor as to degrade the performance of anAdcock aerial. Instantaneous automatic direction finding atall aircraft frequencies is provided by Stan- dard Telephones & Cables PQ range, whichemploy the latest commutated antenna tech- niques. CADF gives from five to ten timesgreater freedom from errors than does con- ventional DF. By electronic time-sharing,simultaneous presentation of DF bearings from two separate channels or equipment canbe displayed on one Type A2208 cathode-ray indicator. For automatic position-fixing anumber of DF stations can be linked to a con- trol room where individual bearing lines areoptically projected on a large map screen. A more recent development is the PVT.2, inwhich the bearings are optically projected from miniature CRDF displays and combined withmap transparencies for presentation on a closed-circuit television system. VOR ground beacons of Type BO.2 are alsobeing produced by Standard Telephones and
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