Sennheiser ew 300 Instructions for Use - Page 68

Diversity reception The EM 300 receiver operates on the "true diversity" principle: A receiving antenna receives not only the electromagnetic waves which reach it by a direct path, but also the reflections of these waves which are created in the room by walls, windows, ceilings and fittings. When these waves are superimposed, destructive interference occurs, which can also be called "field strength gaps". Repositioning the receiving antenna can bring a solution, provided the transmitter remains in its original position. With mobile transmitters, however (which all radiomicrophones are ), the "field strength gap" will then occur with a different transmitter position. These "field strength gaps" can only be eliminated with true diversity receivers. In true diversity, instead of one antenna and one receiver there are now two antennas and two receiver sections. The antennas are spatially separated. By means of a comparison circuit, the receiver section with the strongest RF signal is always switched to the common AF output. The risk of the occurrence of "field strength gaps" in both antennas at the same time is virtually nonexistant. The receiver display panel shows the active diversity section (I or II). Control signal Receiver section I Electronic switch-over of AF signal Control signal Receiver section II 68