Radio Broadcast (May 1928-Apr 1929)

WHIPPANY Will New Transmitting Methods Be the Remedy? By Edgar H. Felix t; 'HE acuteness of the broadcasting congestion problem focusses public attention upon any method suggested to increase the capacity of the broadcasting band. Many proposals have been made, some of which hold promise and others which, if put into practice, would only increase the existing confusion. Since the regulation of broadcasting has become a political matter, the great danger exists that the statements of pseudo-scientists may be accepted and untried plans for station synchmnization will be forced into practice before they have been fully developed. There are only two possible ways of reducing congestion in the broadcast band: (i), large numbers of stations must be eliminated, reduced to part time, or curtailed in power, or (2), the number of stations of a given power, successfully occupying the same channel, must be increased. Time division is already practiced to such an extent that further relief cannot be expected from this source without too much restriction of the service and earning power of existing stations. Power reduction will only lessen the value of better stations; the tendency is toward increased power because it means better program service for greater numbers. Legal and political considerations make it impossible to ex pect wholesale station elimination as a source of the radical improvement necessary for good broadcasting service in every section of the country. Consequently, the only measure of relief which can be effective is the development of Service Range and Interference Range 'THE following table shows how the power radiated by a broadcasting station *■ affects, (a) the " service range," which is that distance over which good reception will be possible independent of static, day and night, rain or shine; and (b) the "interference range," which is that distance over which the carrier wave of a broadcasting station can mar reception by generating a heterodyne whistle with the carrier wave of another station: Miles Antenna Satisfactory Hich-Grade Carrier Power in Watts Service Service Interference Range 5 10 1 100 50 22.5 3 250 500 65 10 625 5000 160 30 1500 50,000 350 90 3000 If we divide the interference range by the high-grade service range we get the following figures: Antenna Power in Watts 5 50 500 5000 50,000 Interference Range Divided by High-grade Service Range 100 83 62.5 50 33 The figures in the right-hand column show clearly that high-power stations approach closer to the ideal condition as the ratio of the interference range to the service range is decreased. some means of increasing the number of stations of present powers operating on the same channel without interference. Many schemes to effect this result have been offered. They fall into three classifications: (1) The elimination of the carrier whistle by accurate control of the carrier frequency of stations occupying the !5SJ<2*>j same channel, permitting service range rather than carrier range to determine the necessary spacing between stations on the same channel; (2) The synchronization of both carrier and program, popularly referred to as placing chain stations on a single channel; (3) The limitation of the carrier range to the service range of the station by the application of new principles of transmission. Before considering in detail the actual methods for each of these general systems, what are the requirements for a plan which will increase the capacity of the broadcasting band? Four major qualifications must be met and failure to meet any one of them condemns any suggestion as useless. They are: (1) The system must be of unfailing reliability in operation. The adoption of closer spacing among stations on the same channel, the objective of most of the systems, ale* 5