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The New Zealand Railways Magazine, Volume 7, Issue 2 (June 1, 1932)

The Carrier Telephone System

page 22

The Carrier Telephone System.

One of the most interesting developments in the telephone field, of which the Home railways are taking advantage, is the perfection of carrier wave transmission systems. The G.W. Railway has just completed the installation of a carrier wave telephone system between Reading and Swindon, on the main-line from London to the West. By means of this apparatus, known as the D-1 single-channel carrier telephone system, provided by Standard Telephones and Cables Ltd., it is possible for two conversations to be transmitted over one circuit at the same time.*

A different carrier frequency is utilised for transmitting at each end of the two terminal stations. In operation, the actual carrier frequency is suppressed at the sending station, and reintroduced locally at receiving point, where the original voice frequencies are reproduced. A clever arrangement of filters separates the “carrier” from the ordinary facilities. The carrier system terminates in the usual switching arrangements, thus rendering unnecessary any special tuition to switchboard operators. The whole of the apparatus at each terminal, excluding batteries, is erected on a 7ft. rack. It is, therefore, practicable for it to be moved without difficulty for use under emergency conditions, or to afford relief on temporarily congested telephone routes.

A Great European Gateway. The Historic Mole at Zeebrugge, Belgian terminal of the Harwich-Zeebrugge Train Ferry.

A Great European Gateway.
The Historic Mole at Zeebrugge, Belgian terminal of the Harwich-Zeebrugge Train Ferry.

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A New Zealand Railwayman's Hobby. Flashlight photographs of an interesting model railway constructed by Mr. A. W. E. Smith, a member of the shunting staff at Dunedin Goods, in a cellar under his residence at 151, Carrol Street, Dunedin. The model railway has been built upon a platform giving 150ft. of track, which, together with the rolling stock, is operated electrically—the power being derived from the electrical system of the house and by the aid of a transformer. With the exception of a few of the “Hornby Series” of models used by Mr. Smith, the equipment—signals, stations, bridges, tunnels, level crossings, and some goods wagons, are all home made. Mr. Smith's son shares with his father the interest and enjoyment found in operating this unique model railway.

A New Zealand Railwayman's Hobby.
Flashlight photographs of an interesting model railway constructed by Mr. A. W. E. Smith, a member of the shunting staff at Dunedin Goods, in a cellar under his residence at 151, Carrol Street, Dunedin. The model railway has been built upon a platform giving 150ft. of track, which, together with the rolling stock, is operated electrically—the power being derived from the electrical system of the house and by the aid of a transformer. With the exception of a few of the “Hornby Series” of models used by Mr. Smith, the equipment—signals, stations, bridges, tunnels, level crossings, and some goods wagons, are all home made. Mr. Smith's son shares with his father the interest and enjoyment found in operating this unique model railway.