The "Relay" and the "Re-Broadeast"

Radio Record, Volume I, Issue 47, 8 June 1928, Unnumbered Page

The "Relay" and the "Re-Broadeast"

HAT are these ‘relays’ and ‘rebroadeasts’ we hear so much about, and how are they done?" asks the "man at the loudspeaker," who is the Ren /e Ae modern prototype of the "man v----= in the street." "Relays" and "rebroadcasts" are two terms which are used somewhat promiscuously by the public. A "relay" is when a telephone line is used to connect the scene of the event to the transmitting station, as, for instance, in relaying a concert from a town hall, the description of a football match from the playing field, or of a race meeting from a racecourse. A "rebroadcast" is when a receiving set is used, 2s, for instance, when 1YA, 3YA or 4YA picks up 2YA’s broadcast from the air and sends it out again. In this case, too, a relay telephone line generally has to be used as well, for the receiving set is usually some distance from the transmitting station. It is placed some distance away in order to be as free as possible from extraneous noises. In the case of 3YA, however, the receiving set is actually at the broadcasting station. That is unique. GREAT POSSIBILITIES, 1B Britain and America the relaying of concerts is an accepted feature of the service. There is a network of wires over both countries and all studios are linked together, and programmes are often arranged so that some items may come from one studio and some from another, the ‘whole being rebroadcast from all stations as though it were one programme from one studio. THE possibilities of relays and rebroadcasts were brought forcibly before the New Zealand public on the occasion of the Ranfurly Shield match at Masterton in July last year, which match was broadcast on relay by 2YA and rebroadcast by 8YA. The telephone line on that occasion was nigh perfect, the Post & Telegraph Department’s engineers having taken meticulous care at every point, and the line was free from outside interference. The next important relay, even longer than the Wairarapa, was on the occasion of the Ranfurly Shield match at Palmerston North. As on the previous occasion 3YA rebroadenst 2YA. Lately, 2YA proposed to relay a concert from Wanganui, 120 miles from Wellington, but a test of the line revealed too much outside interference and the project had to be temporarily abandoned, WHAT ACTUALLY HAPPENS. RELAY lines necessitate considerable arranging, and the transportation of much apparatusin the’ way of microphones, portable telephones and amplifiers. When a relay is proposed the Post & Telegraph officials have to be notified, and. they complete the line of communication between the studio and the place where the microphone is to be. This does not require the erection of a new line all the way. Between the Post Office and the studios is an underground cable containing a large number of insulated telephone wires in pairs.- Where they enter the exchange

they are terminated in the usual manner on the main distribution frame, and at the studio end terminated in rows of ‘‘jacks," each pair of wires going to each "jack."" When the Post & Telegraph Department is asked to connect up with a certain place where the affair to be broadcast is taking place, the Department avails itself of a pair of the many spare wires which it usually has in one of the cables in the vicinity. From here new wires are run to the place required, which is thus connected through the exchange with the ‘lines to the studio. A MINIATURE EXCHANGE. With a complete line from the microphone t9 ‘"" + the studio, the control man in the broadcasting station then has the music, the speech, the boxing, the football, or whatever it is, on tap and all he has to do to send it on to the operator in the transmitting room is to insert a plug into the ‘‘iack." In the announcer’s room at each station the array of "jacks’’ make a miniature exchange. Some are for permanent relays (for instance, theatre orchestras ‘which are regularly on a programme); others are tonly connected up temporarily, that is, for some special occasion. Here it may conveniently be mentioned that during the Christchurch Diamond Jubilee celebrations last week 8YA carried out 22 relays. WHEN a relay is being carried out, the Post . & Telegraph Department goes to great trouble to get as perfect a line as possible, but there frequently are factors which arise at an inopportune time, and over which the engineers have no control. Listeners then write to the Broadcasting Company and complain about the "noisy" relays. A SPECIAL ‘ MIXER." HE sending out of a microphone to the scene of action does not end the preparations so far as the Broadcasting Company is concerned. The other apparatus mentioned goes too. The Post & Telegraph men carry out their tests of the line, and an hour or so before the time of the performance a relay operator is sent out from the studio armed with the necessary microphones, batteries, amplifier and probably a "mxier," all intended to secure the best result. In cases where noise or induction are prominent, it is necessary to magnify at the microphone end the volume of the voice or music to a fairly high value in order to override the noises which are later picked up on .the line. This amplifier is of a similar type to that used when items are being broadcast from the studio, but of course lacking many of the refinements of the studio amplifier. N the case of some relays, as in the Christchurch Cathedral, when the service is not conducted from one fixed point, it is necessary to use a number of microphones so as to pick up all portions of the service. On such occasions a special apparatus known as a "mixer" is used by means of which the output from a number of microphones may be combined ard put into the amplifier in the proper proportions. ‘4

STABILISING THE VOLUME. PART from the drowning of the extraneous noises on the lire, the purpose of the amplifier is to bring the volume up to a useful value. The ordinary broadcasting microphone is, in spite of popular opinion, a very insensitive device, much more so than the conventional household telephone, Owing to details of construction rendering it of exceptionally high quality, the volume level is sacrificed, and it is to bring the volume up to a useful value that the amplifier is used. GREATLY magnified, the music or speech arrives too loud to be put upto the studio amplifier without causing it to be overloaded. Under these circumstances the volume level is reduced by means of an artificial line or resistance network until a suitable volume is obtained. Then the music goes through the usual studio equipment and into the transmitter in the same way as when items are rendered in the studio, SY rebroadcasting, a similar procedure is adopted but it differs ty the extent that a good receiving set instead of a microphone is used at the relay end. A locality is chosen which is reasonably good for radio recepticn, and the broadcast which is picked up is sent through the telephone line and through the studio amplifier as for a relay. N some cases, as at 3YA, an outside receiving station is not needed. The reception is done in the transmitting room. Listeners frequently complain about the difficulty of cutting out a local station in order to listen to another, but it is only a question of using a sensitive receiver and an efficient wave-trap. This is evident from the experience of SYA where the antenna is strung between the towers underneath the aerial which transmits 500 watts, and where the receiving set is only eight feet away from the transmitter.