POLICE PATROL.

Auckland Star, Volume LXVI, Issue 68, 21 March 1935, Page 5

POLICE PATROL.

RADIO MOTOR CARS. FLYING SQUAD'S WORK. RECEPTION AND BROADCAST.

The latest application of radio as an aid to crime investigation and prevention in Britain is a great advance on anything previously tried. The apparatus is carried by police wireless patrol men al? over the country. The box is about nine inches high, eight inches wide and just over 16 inches long. It weighs 211b. There seems to be hardly anything inside it. Yet, j when carried in a police car, it enables the Flying Squad men to talk to Scotland Yard or to their local police headquarters, writes Kent Barnett in "The Motor." It makes it possible for policemen on their beat to ring up the central police station and report crimes immediately, thereby shortening the time available for the criminal's escape. For years the special branch of the mobile police has carried wireless j receivers with which it is able to pick up messages from Scotland Yard. Yorkshire police took up the idea and improved it. Other provincial centres followed, and chief constables who had done war-time service vied with each other in brushing up their Army radio experience and putting it to good account for the force. A Full-Time Listener. Then Scotland Yard decided to have a full-time mobile squad, and hundreds of cars were introduced into the metropolitan area. Many of them carried wireless receivers so that the passenger (generally a sergeant) could listen-in for instructions. The order was then

issued that a full-time radio man should be taken in each car, and that he should wear a single earphone over his head, constantly listening for police reports from Scotland Yard transmitters.

Many of the police radio men were exnaval radio operators. But there was a weakness in the whole scheme; the men in the cars could only receive orders from the central stations. They could be directed by radio to the scene of a crime, but they could not report | by radio back to headquarters. Precious time was wasted in searching for a phone box. So experts began to plan a miniature transmitter which could be carried in the flying squad cars, or even on a roadpatrol motor bicycle, and give the men on their beat a chance to speak back to the Yard men with their finger on the crime centre. The Magic Box. Eadio technicians who had designed special for Imperial Airways and the R.A.F. turned their hand to similar sets for the police. Eventually the magic box was built and given to the Scotland Yard engineering section and provincial chief constables to try out. It is a broadcasting station in miniature. As it is so compact it can be tucked under the seat of a police car. . There are only three valves in it. It needs no cumbersome batteries, for it is connected up in only a minute to the car or motor bicycle starting or lighting battery. The three valves are lit direct from this battery, and the high voltage necessary for a broadcaster (no matter how small) is obtained from a little dynamo driven from the starter battery. Aerials do not bother the police. These special police sets broadcast with a single telescopic metal rod iift long, extending to Oft. The rod can be carried by the operator or can be fixed to the side of his car. If there is no room for the rod outside the car (or if he does not want bandits to know that his car is radio-equipped), a wire grid is hung just inside the roof of the car, invisible from the outside.

This set does not need a radio expert to work it. There are no knobs to twiddle. A cover fits over the front of the box to protect it. This is quickly removed' by means of two snap catches when it is desired to retune the transmitter. This can be done by a radio expert before the constable leaves the station. The front is then fixed 011, and all he has to do is switch on. Sometimes the constable wants to talk back to headquarters in absolute secrecy. Then he uses dot-and-dash # code, unfolding a little Morse key from the front of the box. The code is absolutely secret. It was worked , out by .Scotland Yard experts from a code used for secret service' work. Wireless enthusiasts who want to listen in to this broadcast will have to search the ether between 100 and 150 metres, for the magic box will transmit on any wave-length between these limits. It broadcasts with a power of 50 watts, which is approximately the same as that taken by a small electric bulb. Nevertheless the range is considerable, and there is never any fading of signals when the box is worked up to eight miles from headquarters. The receiving set is mounted in special quick-release brackets so that it may be removed for servicing and replaced by another. All that is necessary for its removal is to take out the aerial, loud-speaker and supply plugs, and slack-off the quick-release thumbscrews. The receiver, complete in its case, may then be removed and another put in its place. By removing the plugs and sockets from the transmitter panel and undoing four screws the transmitter may be withdrawn from its case for replacement by another. A small panel is clamped to the steering column of the police car and on this is a switch with which the operator can turn on the receiver or transmitter. When the switch is clicked one way he can pick up orders from headquarters. When it is turned over in the otner direction he can tell the "Yard e lit » what is happening on his beat. * 1 light glows on this panel all ' e the transmitter box is £w he is just to remind the constable that °Theso 'police miniature broadcasters have passed through thc te ® tin /. r J