WIRELESS IN WAR.

Otago Witness, Issue 3470, 14 September 1920, Page 51

WIRELESS IN WAR.

REMARKABLE DEVICES. (The Times Special Correspondent.)

In the late war communication by wireless was brought up to a remarkable pitch of excellence, and some of its secrets have been revealed since the coming of peace. The public thus have some knowledge of how the whereabouts of the enemy were discovered by the interception of his wireless messages, of the comrnimication between observing aeroplanes and the guns, and of' the control from their bases in Germany of raiding, airships. Demonstrations have been given recently also of directionfinding by wireless. It is now intended to equip the army with wireless oh a far wider and more general scale than hitherto. From the nature of its work as a' fighting machine, it is essential that the army should have wireless equipment of a distinct and definite pattern. Never was high speed transmission more needed than in°the midst of a general attack. There are instruments at Woolwich that have actually transmitted messages at the rate of over a thousand words a minute. The application of. such appliances to the transmission of press messages would revolutionise daily newspaper journalism. They would make it possible to telegraph the' news columns of an edition of the Times in their entirety to foreign countries in about two hours and a-half. In one of the rooms at Woolwich there is laid out a miniature wireless direction - rinding set, with which one may perform the exact operation in little of discovering the whereabouts of another station, whether it be on sea, land, or in the air, which is sending out messages. The direc-tion-finder is situated at a fixed spot on a "map, the distant station is moved about anywhere one pleases on the same map, and the sound waves picked iro from it, varying with the mqA'ement, lead inevitably to the accurate determination of its position. The principle of this revolving form type of direction-finder turns on the properties of a closed loop of wire. When the closed loop forming the wireless receiving aerial is turned edge on to the direction of the transmitting station it will receive maximum signals, and when turned at right angles to the transmitter the signals fade out or are reduced to a minimum, thus determining the direction of the transmitting station. The early revolving forms in use during the war were about 10ft or 15ft square, and were somewhat clumsy. The latest pattern is abotffc one-seventh of that size. It has q- range of 250 miles, and is accurate *co one degree. In another room in the experimental Fiction there is a remarkable instrument which transforms ordinary ground-line tele

graphy into "wireless. There is no limit to the distance from which the original message may be received, so long as the sender is connected by ground-lines to the wireless station. All he need do is to call up the latter and state that he wishes to begin to send. The power at the wireless station is set in motion by an engineer, and a green light switched on in the operator's cabin tells him that all is ready. He then begins to tap out his telegram, or send it by the Wheatstone machine, and it passes into the wireless station as it is telegraphed and out again in wireless waves, the transformation having been effected by the machine itself without human aid.

Without going further into technical details, it may be said that with regard to transmission no difficulty is anticipated in controlling the largest power valve sets at speeds of 450 words per minute by means of ordinary post office apparatus. The receivers indicated will be practically immune from interference, except, of course, from stations operating on the same wave length, and they will be capable of_ dealing with traffic at 450 words per minute when using standard post office recording instruments. Another instx-urnent seen at Woolwich is an amplifier, which enables the receiver of messages to cut out all waves save that he wishes to hear, and to increase the intensity of the desired signal. It has been brotight to such a pitch of perfection in so far as its powers of filtration are concerned, that its user can listen to a sending -station hundreds of miles away, undisturbed by the working of another wireless set in the same room where he is employed.