The most critical issue the FRC faced at the time of its creation was an excess of broadcasting stations, which now numbered 732, all on the AM band. (The FM broadcast band would not be created until 1941). There were some significant technical restraints on the number of stations that could operate simultaneously. At night, a change in the ionosphere allows radio signals, especially from more powerful stations, to travel hundreds of kilometers. In addition, at this time transmitter frequency stability was often limited, which meant that stations broadcasting on nominally the same frequency often were actually slightly offset from each other, which produced piercing high-pitched "heterodyne" interference at even greater distances than the mixing of their audio. Another tool that was not yet available was directional antennas that could restrict signals to specified directions. Overall, the main tools available for insuring quality reception was limiting the number of stations operating concurrently, which meant restricting some stations to daytime-only operation, and in many cases requiring time-sharing, where up to four stations in a given region had to divide up the hours each used on a single frequency.
the most critical issue the frc faced at the time of its creation was an excess of broadcasting stations which now numbered 732 all on the am band (the fm broadcast band would not be created until 1941) there were some significant technical restraints on the number of stations that could operate simultaneously at night a change in the ionosphere allows radio signals especially from more powerful stations to travel hundreds of kilometers in addition at this time transmitter frequency stability was often limited which meant that stations broadcasting on nominally the same frequency often were actually slightly offset from each other which produced piercing high-pitched "heterodyne" interference at even greater distances than the mixing of their audio another tool that was not yet available was directional antennas that could restrict signals to specified directions overall the main tools available for insuring quality reception was limiting the number of stations operating concurrently which meant restricting some stations to daytime-only operation and in many cases requiring time-sharing where up to four stations in a given region had to divide up the hours each used on a single frequency