TELEGRAMS.

Auckland Star, Volume LXX, Issue 199, 24 August 1939, Page 10

TELEGRAMS.

A HUNDRED AT A TIME.

The latest advance in communication make* possrble tftie sending of not less than 96 telegraphic messages in one direction over a single circuit simultaneously. It wu recently demonstrated publicly by Western I nion engineers and the system is now in commercial operation. Over the first practical telegraph invented by Morse, one message was sent at a time, one wire. As the volume of telegraph business grew the duplex system was invented, by which two messages can be sent over one wire. Then Thomas A. Edison produced the quadrnplex system for Western Union Company. permitting transmission of four messages simultaneously. Later the multiplex system was developed, by which eight telegrams may be sent oyer one wire at the same time. The new system is an improved "carrier current ' arrangement. It is so called because it uses a number of musical tones which are sent over the line circuit, and each separate tone carries telegraphic messages. By using a large number of such tones it becomes 'possible greatly to increase the number of messages which can be carried over, the telegraph wires. ( To furnish the numerous pitches or tones of the carrier system, the engineers found it convenient to make use of the equipment that is used to generate the musical tones in the Hammond electric organ. In the organ the key which is A above middle C on the keyboard. as an example, produces a frequency of 440 cycles, that. is. 440 vibrations in each second, and produces that note from a tone cabinet. Each other key produces a tone" of another frequency.

For the carrier system the engineers found that by choosing pitches .">OO cycles apart they could readily put 22 on a single circuit. But each of these pitches can carry a number of messages by methods previously used, with the result that a total of 06 messages in one direction is made possible. This system represent*? the latest, development in what, for some time, has been known to communication engineers as a voice frequency carrier system, but with lower message capacity.

Another feature is a "tone detective," which, by a series of lights placed on clefs of the musical scale, shows the frequencies of the tones produced on the organ, and the tones being used at any time by the generator in the carrier channel system. When Virginia Oman, famous American concert organist, played the instrument, the "tone detective" followed the corres[>onding lights without any wired connection whatever between the two.