Eliminating Wireless Microphone Interference with Antenna Diversity
Tom Colman from Shure UK's Systems Group explains how antenna diversity can eliminate interference in your wireless microphone system
Interference is the most common problem associated with wireless microphone systems. Multipath interference, to be precise, is a phenomenon in the physics of radio waves whereby a wave from a source travels via two or more paths and, under the right condition, the waves arrive at the antenna at different times and can cause interference.
This interference can be extremely annoying and interrupt a speech or performance if not corrected. This common problem can be resolved by antenna diversity, or the process of using two or more antennas to improve the quality and reliability of a wireless link.
There are three different types of antenna diversity offered with wireless microphone systems depending on the system's ability:
Predictive Diversity involves one receiver section and a switch that chooses the receiver with the strongest signal. The predictable comparator will listen to the audio being received. When the signal to one antennae is weak, the comparator automatically switches to the other antenna. This is a fairly effective method offered by entry-level wireless systems.
True Diversity employs two antennas and two receivers, and provides an audio combining circuit for the two antennas using two dedicated receiver sections. In this system, the comparator switches between audio feed 1 and 2, rather than between the direct antennas. This is a stronger and more reliable method.
Maximum Ratio Combining Audio Diversity is very similar to True Diversity, but rather than having a switch that moves from receiver one to two, it acts like the crossfader on a DJ mixer and switches between the two antennas. If it has tone key and is receiving strong audio quality to both receivers it will set the fader in the middle. As soon as one of the signals starts to get weak it will pan towards the receiver with the strongest signal.
This content is an excerpt from Shure UK's Wireless Mastered: Installed seminar. Click here to join our mailing list and receive notifications about future Shure educational events. You will also receive a free download of the Shure Wireless Microphone Configurator.
