PICTURES BY WIRELESS

Cue (NZERS), Issue 14, 31 December 1944, Page 24

PICTURES BY WIRELESS

A COMPARATIVELY .few hours Y~l after the invasion of Europe, pictures of the landings 'on the Normandy beaches appeared in Australian newspapers. Within seven days of D-Day, New Zealanders were seeing for themselves how Allied soldiers began their assault on Hitler's Atlantic Wall. They were not blurred, streaky •pictures, but well-produced photographs

of exciting incidents. The New Zealand public became intrigued and curious. How was it done? The answer is beam wireless, plus a little assistance from modern aviation in the final stages. Just as wireless broadcasting and receiving has been im- ; proved in recent years, so has the pic* turegram” technique progressed, until now pictures can be transmitted across

the world in a few minutes and reproduced with remarkable fidelity. It is done by a system depending on a combination of mechanics and electronics, which appears almost fantastic and Wellsian to. the layman, r ■

In their progress from' the beaches of Normandy to the pages of the New Zeaand newspaper, the pictures have passed through many hands - and processes. From France to Britain, they travelled by ship; from Britain to America, they were flashed through the air, until, from a beam wireless studio in San Francisco, they began their journey across the Pacific to Melbourne. From Australia they were flown to New Zealand, and. a few hours later were being produced in the daily press. Here is how it was done. A’Hullo, Melbourne! Hullo, Melbourne! Are you ready?” An American voice bursts in on.the Melbourne beam wireless studio. A few minutes before, studio technicians had pulled various switches, and signals were set in operation in the ’shining, black and chromium power plant, energised by two circuits of 62, • valves each. The receiving relay station Melbourne and San . Francisco ■had announced that the picture would be put through as soon as the "all clear” had been given.

The operator set his gear according to the signal tones coming through from the American station. A The frequency of those tones, reflected in the receiving studio by the intensity of the light, governs the picture, within the shade limits of black and white.

Suddenly, a purple light springs up at the back of the equipment and is carried forward by an optical system, through right-angled prisms to a steel cylinder, which is-the base for the sensitised film. Rotations.of the drum,under the cylinder are then controlled to place the light in perfect synchronisation with the . tones. The technician makes fine adjustments and the light glow’s dead on the .signal dot. He then'brings the dot . into a convenient position on the drum for readings

• Complete harmony between transmitting and receiving stations is; achieved

and maintained by identical forks whose vibrations, down to one in 100,000, with due allowance for expansion and contraction of the metal, are controlled by temperature. The thermostat chambers do not waver from the standard for any. second of any day in the year. . .».

"0.K.," the Melbourne operator buzzes back in Morse.

"Go ahead,-Melbourne," comes back the American voice, for San Francisco uses direct speech and . Melbourne the Morse key.

A double row of heavy black curtains is drawn across the doorway. The technician places an orthochromatic negative on to the cylinder and the process of converting an invasion scene' into tone in San Francisco and reconverting it into identical light value in Melbourne is begun. / . .

The light, which is the printing medium revolving under the negative, moves laterally along the cylinedr, committing the tonal shades to the surface of the negative, line by line. The light moves at the rate of four scanning lines to the millimetre or about 101.6 to the inch. If the synchronisation was not perfect, the outlines would be "staggered" and the pictures useless for commercial purposes. Depending on the size of the pictures, the time of transmission ranges between ten and eighteen minutes, one second being allowed for the scanning of ‘ the line eight inches wide. ...

Round and round goes the drum, the inner light flashing periodically, as it traces its almost magical patterns. The staff moves about quietly, aided by red torches. The heavy curtains keep out unwelcome light, and a lamp outside the doorway warns off any possible intruders.' _ •

"Hullo,Melbourne. That is the end. Do you think you’ve got a picture?" ; The operator’s task is over for the moment. A -photographic expert whisks the‘negative from the cylinder and immerses it in a. developing bath for five minutes, and thence into a fixing solution. Then she makes a brief inspection.

"0.K.,” she says, and the technicians prepare to receive another "picture gram." v " ‘- 'A