AKG Acoustics WMS 400 manual Akg Wms Multichannel Technology, Shadow loss, Multipath transmission

AKG WMS MULTICHANNEL TECHNOLOGY

Shadow loss:

Shadow loss means that the signal path from the transmitter to the antenna is interrup- ted by an obstacle.

Multipath transmission:

A radio signal travels to the receiver not only along the direct path but also along several alternative routes as the signal is reflected off or diffracted around all kinds of structures. So the same signal arrives at the receiver at different points in time and in different conditions.

Diversity systems help to eliminate transmission problems caused by shadow effects or multipath transmission.

Non Diversity Dual antenna diversity True diversity technology

Wireless systems with a non-diversity receiver have to pro- cess the signal in whatever shape it reaches the antenna. Even with moderate distances between transmitter and receiver, this results in more frequent – and therefore very disturbing – periods of signal dropout.

When the RF signal level of the antenna path being used becomes too low, the switching circuit connects the recei- ver input to the other antenna. If this fails to provide a higher signal level, the switching circuit reverts to its ori- ginal position. The disadvantage of this system is that it only checks whether the RF signal level of the second antenna is higher once the level at the first antenna is already too low. Differences in the signal/noise ratio are not even detected at all.

In contrast to antenna diversity, true diversity not only employs two antennas, but two receivers as well. The switching circuit compares the quality of the two signals and routes the better signal to the output.

www.akg.com 33