Getting the• Best Out of Two-way Radio
Page 45
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THE use ot two-way !radio to control various kinds of road transport operation has raised many, problems. Perhaps the
greatest of these has been the suitability of sites for base transmitting masts and the choice of equipment, both of which difficulties can hardly be overcome by the transport operator without expert advice.
To provide such a service, Marconi's Wireless Telegraph Co., Ltd., Chelmsford, has equipped a team of vehicles and engineers.
Modern methods of making radio equipment in small units have allowed the manufacture of compact, dependable transmitter-receivers which can be accommodated unobtrusively and run off the vehicle's normal battery. With such mobile installations and a headquarters transmitter-receiver to act as a control, a network can be set up.
Without a preliminary survey and an accurate diagnosis of the problems arising,however, such a network might xvell be too expensive. A headquarters installation set op without a survey, for instance, may often reveal blind spots when set to work. This fault is usually because of the poor siting of the station and can normally be obviated by careful selection in locating the aerial and correct choice of equipment. This is the type of service which the Marconi mobile team performs.
Variety of Equipment
The modern fleet of Marconi mobile wireless stations contains a comprehensive collection of mobileand fixedstation equipment which, used during survey work, allows the engineers and prospective users to decide which is the hest for the specific purposes.
The team has a Cornmer van and Iwo Hillman Minx estate vehicles, the Cotniner being equipped as a headquarters station and the two Hillmans as mobile stations. Their purpose is to survey a given area, operate over it with the type of equipment suitable for the particular purpose envisaged, and plan the siting of headquarters stations to ensure maximum coverage.
The Cornmer vehicle is based on a 21-ton chassis and its body lines resemble those of an ambulance. The coachwork was built to Marconi design by J. S. Keam and Co., Ltd., Berkshire Road, London, E.9. There are no side windows, as the interior fittings, being of varying heights, made it difficult to give symmetry. Transparent cant panels are fitted.
Comfort during long-distance tours was a major consideration and welh cushioned bucket seats have been installed. The van is completely selfcontained and can remain away from base indefinitely. It carries three main types of headquarters equipment. They are a 5-watt transmitter-receiver ,used in conjunction with similar mobile sets, a larger model of 10 watts output, and a 'main headquarters installation designed tat-cover a wide area.
Aerial-mast sections are carried on the rOolof the vehicle and are held in position by clamps. Hinged footholds at the rear of the van give access to the roof and a compartment for stowing mast rigging. Two sets of clips for erecting an aerial on the van are also fitted to the rear.
A petrol-driven alternator is stowed in a compartment on the near side. When the door of this compartment is swung down, it rests horizontally 'on collapsible legs. '
A lead-lined battery compartment which accommodates four normal-size batteries is positioned on the off side. The mterior is divided into a demonstration section and a workshop. Ancillary equipment in the van includes provision for cable-drum storage, a map table and a battery • charger. All power supplies are brought through a main distribution panel which supplies 230 volts A.C. or 12 volts D.C.
An article describing the various applications of two-way radio and different makers' equipment was published in "The Commercial Motor," dated April 7, 1950.