Eliminating Wireless Dropouts
Multi-path interference is the most common cause of wireless drop-outs, and if you can get rid of multi-path, you can get rid of a good number of headaches. So what exactly is multi-path interference?
This post explains multi-path, diversity receivers, and a new antenna for eliminating the problem.
When a microphone transmitter sends out a radio wave signal, it spreads through a room, like ripples on a pond. As the wave encounters flat surfaces, like walls and ceilings, it reflects and continues forward at different angles. Since there are multiple surfaces in every room, there are multiple reflections and hence multiple paths--some longer and some shorter--that a wave takes before reaching the wireless receiver.
Usually, the receiver is able to process two or more signals arriving at slightly different times without difficulty. But if the signals overlap in such a way that they cancel each other out (creating a “null”) you get a drop in volume or complete drop-out. Sometimes, the shape of the room can cause a multi-path null to perpetually hover over a receiver. Other times, when the speaker walks past a certain spot on the platform, a dead spot will develop and you’ll hear a quick drop-out.
Diversity receivers filter out multi-path interference by using two antennas instead of one. Most wireless receivers that have two antennas are diversity receivers. Since a multi-path null occurs only in specific and relatively small locations, it is less likely that a null will exist over both antennas. This is called “spatial diversity.” But spatial diversity does not work 100% of the time.