EMC performance measurements for professional wireless microphone systems

With shrinking spectral bandwidths and more intense use of the remaining frequency areas, the importance of good electromagnetic compatibility (EMC) performance of professional wireless microphone systems, as used by broadcasters, is increasing. A wireless microphone system consists of one or more pocket or handheld transmitters and usually the same amount of receivers. Both have to be immune against disturbances, and on the other hand they should not produce interferences. This paper deals with electromagnetic compatibility (EMC) performance tests of three analogue professional wireless microphone systems. The authors describe the complete measurement procedure using two different setups. These setups employ the pocket transmitter or the receiver as device under test (DUT). Different disturbance signals are used utilizing amplitude modulation (AM), frequency modulation (FM) or digital video broadcast-terrestrial (DVB-T). The audio quality of the transmission system is rated with the total harmonic distortion plus noise (THD+N). Additionally, the authors investigate intermodulations (third harmonic) caused by the transmitter. The results of all performance tests are extensively discussed.