Radio Channel Selection for Interference-Free Operation

A procedure for the selection of mutually-interference-free (MIF) radio communication channels has been devised. Cross-modulation interference and various forms of intermodulation products were considered, as well as other interferences representative of real situations. The channel-selection process consists of the assignment of a priority to all previously-accepted channels over all later trial channels that result in an interference-producing condition. This results in the maximum number of MIF channels that can be obtained by any presently-known practical method from a given available bandwidth. Use of the procedure indicates that a 40-60-per cent increase in the maximum number of MIF channels may be achieved by reallocation of frequencies in the 225-400-mc band. Reassignment would not penalize any of the services entitled to use of the military VHF/UHF band. The use of a slide rule "Radio Interference Calculator," developed specifically for the problem, considerably reduces the computations required for MIF channel selection.