Some Possibilities of Intelligence Transmission When Using a Limited Band of Frequencies

As an ideal lower limit, certain possible methods of radiotelegraph transmission may require only a single side band of 25 cycles for each 100 words transmitted per minute, so that each average present-day short-wave channel provides enormous potential facilities for radiotelegraph transmission. Neglecting the requirements for the separation of channels to avoid interference, the maximum potential traffic capacity of the entire short-wave spectrum down to 10 meters is something like 500,000 stations, each transmitting at 100 words per minute and using a double side band. This figure does not take into account the possibilities of directional transmission, and assumes each station has worldwide range. The problem of utilizing these possibilities is economic and broadly political as well as technical; engineering methods can be developed more highly than at present, whenever the economic value of the new channels created is sufficient to pay the cost. The ultimate capacity of the broadcast band may approach one program per three channels for every listener. If synchronizing proves to be successful, by giving each broadcast chain a band of frequencies about 30 kc wide and requiring that the stations of the chain be divided into three groups, with each group operating on a different common frequency within the 30-kc band, the amount of broadcasting made available to the public may be enormously increased.