An Electromagnetic Compatibility Figure of Merit (EMC FOM) for Single-Channel, Voice-Communications Equipment (A Status Report)

An EMC Figure of Merit (FOM) for single-channel voice-communications systems, based on the channeldenial concept, was developed by using a buildingblock approach [1]. This approach assumes a co-site environment and involves the use of relatively simple scoring formulas for selected EMC parameters, which are linearly combined, with appropriate weighting factors, to calculate FOMs for transmitters, receiv­ ers, and systems (i.e., transmitter-receiver pairs). The parameters chosen for transmitters included spuri­ ous emissions, noise near the carrier (i.e., broad­ band emissions outside the band containing desired modulation components), and iritermodulation products. The parameters chosen for.receivers were spurious re­ sponses, adjacent-signal interactions, and inter­ modulation products. The parameter scoring formulas were developed to reflect the frequency spectrum de­ nied by each parameter. A channel was considered de­ nied if (S + N + I)/(N + I) < 10 dB in a moderately dense co-site environment. The weighting factors for the building-block approach were determined by run­ ning a computer program .that kept track of the number of channels denied by each parameter.