Radio Broadcast (May-Oct 1922)

320 Radio Broadcast " Radio compass service" consists of a direction-finding service to which a mobile station transmits, and which in turn transmits back to the mobile station its bearing or position. Marine radio telegraphy includes all radio service between ships at sea and between ship and shore. By "technical and training school" is meant a school which carries on instruction for the training of men for the radio service. "Amateur" is defined as one who operates a radio station either transmitting, receiving, or both, without commercial gain, merely for personal interest, or in connection with an organization of like interest. It is also of interest to note that public safety broadcasting on the part of city and state organizations, in small cities especially, is expected to be conducted by the interruption of other types of broadcasting service in case of emergency. In the larger cities, however, this service is quite apt, ordinarily, to employ its own stations, under which circumstances it will be confined to the use of the wave band 275 to 285 meters. A cooperation of private detective agencies with municipal or state services in the use of this wave band is recommended. HOW AMATEURS ARE AFFECTED OTHER provisions which have been recommended have to do with that band of wave lengths allotted to amateur radio work, for it would seem best that this band be divided into smaller bands of different types of transmitters. The lowest wave lengths within this band would naturally fall to that type of station which creates disturbances over the broadest band of wavelengths, while the higher wavelengths (those nearest the waves assigned for private broadcasting) are available only to that type of transmitter which uses the most advanced methods, — continuous wave transmitters. Between these, in the order of their merit, fall radio telephone stations and interrupted continuous wave stations, and any radiophone broadcasting carried on by amateurs must be done within this wavelength band. Further recommendations have to do with the limitation of power, the geographical distribution, and the hours of operation of broadcasting stations. Thus all present broadcasting needs may be taken care of for the time at least, while it is expected that greater freedom will follow the expected rapid advancement of the radio art. In considering the causes for interference and some unnecessary sources of interference, it is expected, of course, that effort be made to utilize the most improved types of transmitting and receiving machines. Certain classes of transmitters cause far greater percentages of unnecessary disturbance than others. Time will eliminate those in favor of the improved types. REGARDING RECEIVERS WITH regard to receivers, some types reject a great portion of any disturbing influence while others do not. Here, too, it is to be expected that the most efficient types will survive. What may seem rather surprising is that certain types of receiving instruments, because of the methods which are employed in them to build up the strength of the signal, also act as miniature transmitters. That is to say, some of the energy which is supplied locally for the reinforcement of the feeble incoming signal gets on to the antenna of the receiving station and escapes, creating disturbances in the ether of exactly the same character as would be created by a small transmitting station. Under certain conditions, even though there may be several hundred receivers of this character within a small area, the disturbances which they created would be of no moment (where the signal from the station which it is desired to receive is strong). On the other hand, where a number of such "transmitting" receivers are within a small area and this area is located at a point remote from the broadcasting station, considerable interference results, and it is common knowledge that in certain communities great difficulty is frequently found in receiving the broadcast programmes satisfactorily. All of these receivers are attempting reception at the same time. They all are adjusted approximately to the same wavelength. Under these circumstances, and, as indicated above, when the broadcasted signal is weak, considerable interference results. Development will, in a great' measure, take care of these things and it is entirely reasonable to assume that within a comparatively short time radio broadcasting will have become stabilized, and as much a part of our dail\' life as our newspaper, our telephone, or even our meals.