Abstract
IN the Journal of the Institution of Civil Engineers of March, a report is given of the interesting discussion of a recent paper by Sir Noel Ashbridge on broadcasting. Sir George Lee pointed out that the Post Office acts in several ways as an auxiliary to broadcasting. An important function which it fulfils is reducing the interference which many listeners experience on their wireless sets from electrical machinery. Last year, it investigated 40,000 cases of interference. The total circuit mileage used by the B.B.C. in the P.O. network last year was about 6,000. A large number is also in use for Continental broadcasts. Every country in Europe has now these special circuits, and they are often used for the broadcasting of special events. It is estimated that if 80 per cent of the mains-operated receivers were in use during some important event, such as the coronation, when most people switched on their receivers, the load on the grid system due to this cause alone would be 250,000 kilowatts. The annual consumption of receivers is about 270 million units, quite an appreciable fraction of the load on the grid. Another interesting statistical fact which Sir George Lee gave was in connexion with the three short-wave and one long-wave station which work to America every day. Several hundred kilowatts are radiated from Great Britain towards America but all the power picked up in America would be only sufficient to raise a fly seven inches high in one year. On land-lines, amplifiers are put in at about every fifty miles and there is therefore a large number of amplifying stations between Great Britain and San Francisco. Each amplifier receives such feeble signals that they are just distinguishable from the inherent noise in the circuit, and it amplifies them only sufficiently for the signals to be received at the next station; yet the total amplification received in that repeated process is 10256, a number inconceivably great !
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The Post Office and Broadcasting. Nature 139, 709 (1937). https://doi.org/10.1038/139709b0
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DOI: https://doi.org/10.1038/139709b0