Abstract
ONE of the results of the modern developments in television technique has been the production on a commercial scale of cables capable of transmitting, with reasonable efficiency, alternating electric currents at frequencies up to one or two megacycles per second. These cables, which are of the concentric or co-axial type, are employed in the first place for conveying from the studio or outdoor scene to the television transmitter, the modulation frequency currents of the scene being televised. Such a cable is, for example, employed by the B.B.C. to connect the Alexandra Palace station to Broadcasting House and other important places in central London. But the scope of the application is now being extended to the use of the cables for the interconnexion of television transmitting stations separated by distances of the order of 100 miles. When the distance covered is of this order, the use of the cable is by no means limited to television, since the frequency band available provides a large number of ordinary telephone channels along the cable, thereby considerably augmenting the normal land-line trunk-connexion facilities. By a suitable arrangement of the relative frequencies, these telephone channels can be operated simultaneously with the transmission of the television signals, and the value of the cable is thus considerably enhanced. At the present time, a high-frequency co-axial cable is being installed by the Post Office between London and Birmingham, and the results of its operation will be awaited with interest.
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Development of Co-axial Cables for Television. Nature 141, 482–483 (1938). https://doi.org/10.1038/141482a0
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DOI: https://doi.org/10.1038/141482a0