Listening-in to the G.P.O.

Radio Record, Volume V, Issue 31, 12 February 1932, Page 7

Listening-in to the G.P.O.

First "Surprise Item" from 2YA

/OR a brief period last Monday week 2YA listeners were privileged to "look in,’ per radio, to the telegraph room at the Wellington G.P.O. Few members of the general public are acquaint- | ed with the telegraph room, with its clattering noise and intricate instruments which, when connected up with the network of wires which now covers New Zealand, can send messages from one end of the Dominion to the other. ‘The reliability of the telegraph system, using the morse code-messages sent in dots and dashes-has been tested and establish--ed for many years. Yet few people outside the ranks of the telegraphists -those men who sit hour after hour, listening to the tap-tap-tapping of someone at the other end of a wire "somewhere in New Zealand"-know anything about it. When we want to send a telegram (or a "wire"’) we hand it over a counter to a clerk and think no more about it, for we know it will "vet there." So, on Monday evening it was a matter of great interest to the layman to learn how it all is done. It was the first of the "surprise items" at 2YA. The first that the listener heard was a rattle of morse signals-just what he would hear if he opened the door of the telegraph room. Then the announcer began his descriptive talk. The listener could imagine that he was himself walking round the room and looking at the instruments as they ticked out the message. "We have taken you over to the instrument room of the telegraph office. Wellington," said the announcer. Click, click, click, went the instruments. "Those Clicking sounds you heard were signals representing the word ‘Hello’ in the morse code and were signalled by a telegraph operator in the Auckland Telegraph Office. Now listen to an operator in the Hastings Yelegraph Office signal the same word -(morse signals were heard)-Now Blenheim-now Christchurch — now Dunedin-now Greymouth-," and after the mention of each town the sienals were heard again.

"We sounds a bit husky, doesn’t he?" said the announcer, referring to the signals from Greymouth, "The slight difference you probably noticed in the gound of the signals from the various oftices is due simply to differently adjusted receiving instruments and not to the fact that different operators were signalling or to the fact that the lines are of varying lengths. You have heard signals from six different offices separately-now hear them all together." A chorus of signals followed. "A babel of sound, you will think, but it is really quiet compared with the noise that would greet you should you enter the room at, say, 11 a.m. on a busy day. The noise would then be multiplied tenfold. At this hour of the night only the larger offices are in attendance, and, as I mentioned before, there is comparative quietness. What often puzzles the uninitiated is how the receiving operator at busy periods can distinguish the sound of his own particular instrument from the

score or more of others that are clattering all around him. ‘The telegraph operator doesu’t find this a difficult matter, for his sense of hearing has been highly developed by years of training, and to the experienced operator each instrument has a characteristic sound of its own. "Where I am standing is known as the morse section of the room. ‘This section is some 50 feet long' by 40 feet wide, and contains a variety of morse instruments. The simplest of all morse systems is the ‘Simplex,’ whic. as the name implies, is worked by on¢ operator at each end of a telegraph line, The next step is the ‘Duplex.’ On this system two operators work at each end. one man sending messages and the other receiving from the distant station simultaneously, the circuit being so balanced that outgoing and incoming signals pass over the one line without interference with each other. Next comes the ‘Quadruplex, which arrangemeut permits of four operators being employed at each end of the one line. Two of these operators are senders and two are receivers, and two messages can be forwarded and two received simultaneously over the one telegraph line without any interference. "Tisteners will be interested to learn how correct time is obtained

at telegraph offices throughout the Doninion. A few minutes prior to nine each morning the telegraphists at Wellington commeuce what is known a> ‘All station’ call, and at every other transmitting centre the same procedure is followed. At Welliugton a supervising officer stands facing a galvanometer which in appearance ix something like a clock. Sharp at 9 am. an electric signal from the Kelburn Observatory flashes to the galvanometer needle, causing it to deflect. and the supervising officer immediately calls out ‘Time.’ which word ix transmittéd instantaneously throughout the country. Just listen a moment while we reproduce the ‘All station’ call’ aud the transmission of time as is done at 9 a.m, each day." The signals followed. "J am now moving the microphone to the machine-printing section, and um standing alongside a table which supports what is called single-channel machine printing «apparatus. . This particular circuit is one which carries telegraph traffic between Wellington and Palmerston North. On a system of this kind, the sending operator operates a machine resembling a typewriter, ‘having in fact almost a similar keyboard. Instead of producing printed characters on a sheet of paper,

however, this machine perforates holes in a ribbon of tape. These holes are signals corresponding to the typewriter keys depressed and are transwitted to the distant station when the tupe passes from the keyboard through in instruinent called a transmitter." Listeners then heard the keyboard und transuitter working. "At the receiving end the signals are printed on a very thin ribbon of tape having a guinmed buck. This tape is cut into suitable lengths by the receiving operator and pasted on to the received telegram form. Many listeners will be familiar with this type of telegram. This single channel system is the baby, as it were, of machine printing systems. I will now move the microphone to the full-grown apparatus. "T am now standing by a long table bearing apparatus associated with what is called the quadruple machine printing system. This circuit I am describing is the one which carries the bulk of the telegraph traffic between Auckland and Wellington, and, when loaded to its fullest capacity, eight operators are employed at each end, Four of these are senders-that is, they perforate tape on a typewriter keyboard-while four are receivers, their duty being fo cut the received tape into suitable lengths and place it on to the telegram form. Fach sending operator’s perforated tape feeds through a transmitter at a speed of 40

words per minute, so that when the four keyboards are being worked at their full capacity 160 words per minute are passing from Wellington to Auckland. At the Auckland end four senders are similarly engaged, so that a total of 320 words per minute are being transmitted over ‘one telegraph line "when the circuit is fully loaded. Hach pair of operators-that is. a sender at Wellington and a corresponding receiver at Auckland-work independently of the others: they constitute in effect a duplex of their own. "There are other high-speed telegraph systems, but few have the flexibility of this multiplex system I am briefly describing. By means of an instrument termed a ‘repeater,’ it is possible to pick up the signals formed by any particular operator at the Auckland end and repeat them into any telegraph jine in this office served by the same machine-printing apparatus. For example, it is possible to repeat the Auckland signals to Christchurch, to Dunedin, to Napier, or to Wanganui; as a matter cf fact, such re-transmissions are of everyday occurrence. "Another striking illustration of the flexibility of the system is. seen in an arrangement whereby one operator can send simultaneously to a number of stations. As I speak an operator here is perforating simultaneously to Auckland, Christchurch, and Dunedin, Press news messages for the morning newspapers, and, if occasion arose, Wanganui and Napier could also be served at the same time." [Tisteners then heard the characteristic sounds of the keypoard perforator, the transmitter, and the printer.] "Listeners will be interested to learn that one of the most important instruments associated with this machine-printing system was the invention of Donald Murray, a New Zealander. Mr. Murray was originally a newspaper man, and the linotype machine used in newspaper offices for the setting up of type gave him the idea of attempting to ‘set type by telegraph,’ as he put it. He succeeded in his object, and gained a world-wide reputation in telegraph circles." "The microphone is now being moved to another part of the room," continued the announcer, "A number of pneumatic tubes terminate at this point; the collecting and distributing centre. Messages from the counter branch and from other parts of the building are received here through the tubes. The messages are enclosed in small fibre carriers, being held in position inside by means of a steel spring. Nearby is another tube running under Grey Street, through which passes cable’ traffic between the Eastern Telegraph Company’s office in Nathan’s building in Grey Street some 70 or 80 yards away from this room. Cable messages

from and to various parts of the world are received and dispatched from this point. The cable, which is terminated in Nathan’s Building, is connected direct to Sydney, the landing-place in Australia being at Bondi, the famous Sydney beach, of which no doubt you have all heard. At the New Zealand end, the landing point is at Titahi Bay, from where the cable is carried in a trench to Wellington. "In this room (the nerve centre of the telegraph system of New Zealand) are many other interesting instruments, but my time is up, and we are now returning to the studio to continue the concert programme, "Good evening,"