Broadcasting To

The Pacific

BBC Asks Residents For Reception Reports

IN a recent overseas broadcast from London, the head of the BBC’s Oucr seas Engineering department, Mr. L. W.

Hayes, outlined some of the problems of shortwave broadcasting from the United Kingdom to the Pacific, and invited listeners to send him reception reports that may be of help in rendering the ser vice even better. Here is what he said — IF you can hear what I am saying, he said, that is proof that the BBC’s Ser vice is coming through not too badly.

But by enlisting youri help we hope eventually to make your reception even better. We need reports telling us about reception at your end —not just that you receive this or that programme—but re ports giving us the wavelength on which you receive best at a particular time.

Right from the start of the Empire Service in 1932, we have been very for tunate in having as a correspondent Mr.

Caldwell, of Suva, who has sent us regu lar detailed technical information about the reception of the Pacific Service —and we are more than sorry that ill health has prevented his continuing to do so.

Secondly, it is most useful if you can give us comparisons between the differ ent wavelengths we have on the air at once—particularly if you find that a wavelength not intended for you is bet ter than one which is intended for you.

Thirdly, we would like to know how reception of the BBC compares with that from other shortwave stations.

NOW .for some of our problems and how we try to solve them. The short est transmission path to Tonga, for instance, is some 10,000 miles long. If the waves travel better over the South Polar regions than over the North Polar ones—and they do at certain times of day—then the transmission path is 14,000 miles long, and that does make it difficult to give you a good service. As you probably know, the shortwaves travel by a series of giant hops—or richochets. They bounce in between the surface of the earth and the ionosphere which is an outer layer in the atmo sphere, some 200 miles above the earth.

To reach Tonga some seven hops or rebounds are needed, and the conditions of reflection will be different at each of the hops, because the effect of the sun will be different.

That presents a special problem, be cause a wave of, say, 19 metres, which happens to be reflected particularly well at the first hop, may not be the right length of wave to be reflected at the

last, and so not reach you at all. On the other hand, a wave which would be reflected well at the last hop may not be the right length to be reflected the first time, and will not get anywhere at all. In either case, you get bad recep tion.

To give you the best choice of recep tion, we put several wavelengths on the air at the same time, but even so there are hours each day—which change throughout the year—when we cannot get through to you in the Pacific on any wavelength.

One way we have of tackling the prob lems is to change the overall timing of the Service approximately one hour per month, going earlier towards June and later towards December.

During the war, however, we adopted a simpler arrangement by extending the overall time of the Pacific Service, and by changing its time only twice a year.

That scheme seems to have proved satis factory, and is being continued.

NOW for one or two general points.

Some of our regular correspondents in the Islands have written to ask why we direct several wavelengths sim ultaneously to Australia and the Pacific Area, and why we cannot be more ex plicit about which of them should pro vide the best reception in any given locality. They ask if we are using sev eral waves in the hope that “something will get through."

That is to some extent true, as I ex plained just now; but let me assure list eners that if it were possible to be ex plicit on this matter we would gladly give full details. We would like to be able to. tell listeners —say, in Samoa — to listen on GSP in the 19 metres band at 8 p.m. for best reception; but, unfor tunately, for several reasons this is not possible.

It so happens that because of the rap idly changing conditions from darkness to daylight at this end, and from day light to darkness at your end, we need to transmit for part of the time over the South Polar regions, and for part of the time over the North Polar regions. Be cause conditions over each of these great distances vary from day to day, we arrange our schedule so as to have two wavelengths available over each path— that is, two in the south-westerly direc tion and two in the north-easterly direc tion —and then let you choose the one that reaches you best.

Of course, at any particular moment all these transmissions may be receivable simultaneously. You do not need me to tell you how large is the total area of the Pacific, and you can imagine that local reception conditions cannot be the same everywhere. The wavelength you get best will depend on the conditions existing at the time; so if your pet fre quency is below normal, do turn to one of the other frequencies in use.

IMUST just say a word about the morse code interference to many of our short wavelengths, which I am afraid increased a lot during the war years. An enormous number of wavelengths were

required to maintain the Armed Forces radio communications over such a large area as the Pacific, and although we made every effort to maintain BBC shortwave channels free of interference, we were not always successful. However, with the war over, we can look forward to this type of interference disappearing.

Here, again, information from you, especially when the call sign of the in terfering station can be given, is most valuable. You see, although the inter fering station is a nuisance to you it may not be audible in England, and conse quently we, at this end, cannot identify it and take action.

To sum up: we need your reports— please give the wavelength on which you get best reception and the time; tell us how the different wavelengths compare; let us know how reception of the BBC compares with other transmissions in the same waveband on the air at the same time; and, if you experience interference, try and identify the station causing it.

Write to The Director, Overseas En gineering Department, British Broadcast ing Corporation, London.