TELEGRAPH INNOVATION

Waikato Times, Volume 124, Issue 20740, 25 February 1939, Page 9

TELEGRAPH INNOVATION

VOICE FREQUENCY SYSTEM 27 CHANNELS PROVIDED New Zealand's latest telegraph development—the use of the multichannel voice frequency system—came into practical use between Wellington and Christchurch three months ago and proved its value during the Christmas rush of telegraphic business. On one pair of wires the Post Office engineers are aide to provide three channels in each direction for telegraphing hy the multi-channel voice frequency system, while each of these channels is also available for working four channels of the multiplex telegraph. But the use of the single pair of wires does not cease with the telegraphic channels, because this metallic circuit is also able to accommodate without overcrowding or interruption of other messages three clear telephone speech circuits, making a total of 27 complete channels of communication simultaneously on one pair of The new system, which is the latest development in telegraphic communication, showed another improved advantage during a long dry spell in January, when telegraphic circuits close to the coast on the North Island and between Blenheim and Kaikoura pave trouble owing in the partial breakdown of the insulating properties of tire insulators on the telegraph poles owing to encrustations of salt contained in spray driven ashore hy nor'-west pales. Salt Encrustation Ordinary telegraph operation which Utilise- an earth return was made difficult. lint the multi-channel voice frequency service continued wilhoul ipriicuilv. a- u,h existence of a com,q,. ,„.q.,llic circuit enabled reduced ins.]! a I ion lo he overcome by a slight inert ase in j, .we Ihe amplifiers. the he_ it s' mar Inlcr.hone carrier ,a - -i: encrustation of insula- | locs on ]iigh-\oii.ige power transmis- - in lines in the Wellington district during the same period caused serious j

interruption in the power supply. An installation of multi-channel voice frequency telegraphy is being provided between Wellington and Blenheim and also between Auckland and Wellington. The latter equipment will probably be completed by the end of February, giving six telegraph channels in each direction while still allowing for three telephone channels between the ttvo centres over the same pair of wires. Over the six telegraph channels it will be possible to provide another four channels of the multiplex telegraph.