Why Wireless Microphones Drop Out

"The Diversity Fin Antenna is simply the best all around solution for multiple wireless mic setups." -Ball Electronics

Understanding Local Interference and Range

Loss of range is typically caused by competition from localized interference, such as that caused by TV stations, motors, LED lighting, anything with a computer chip, and now cell phone service in the 600 MHz band. These sources, added together, form your noise floor. Directional antennas and bandpass filters can work together with high-quality coax cables to help mitigate this problem.

Understanding Multi-Path Interference

Multi-path interference is caused by reflections of your transmitter’s signal, primarily by metal objects in your venue and other boundaries. These reflections flip the polarity of the signal and arrive out of phase which causes cancellations in your receiver’s antennas.

Understanding Cross-polarization Fades

Cross-polarization fades (aka signal cancellation) happen when your direct signal and reflected multipath signals mix in your antennas. This can be somewhat mitigated by proper antenna positioning. However, since multiple antennas must be separated by distance to avoid interfering with each other, the signal in each antenna will not be in the same wave period (phase).  For maximum efficiency the receiving antennas for your wireless microphone systems needs to match the polarization of the microphone transmitters.  

 

 

"FOH Productions proudly uses a multitude of RF Venue products. They are reliable every single time, easy to use and operate, and eliminate any wireless dropout issues one might possibly have while on show site.

The audio crew is always excited when they pop open one of our kits and see that it contains RF Venue products."     -FOH Production

 

 

 

 

Know Your RF Spectrum

As more wireless devices compete for less available spectrum (RF "real estate"), understanding your wireless microphone system's operating conditions has never been more critical.  It used to be the "auto scan" button on wireless microphone receivers was suitable to scan and sync frequencies to your microphones.  Nowadays there are so many sources of interference that establishing what the baseline conditions look like in your venue is a critical first step.

Create a Link Budget

An RF link budget is a very basic calculation anyone can do to get a sense for how well their wireless mic system will perform.  Creating a link budget starts with the power output from your wireless mic transmitter.  More is better, right? Well yes and no. More power increases intermod problems when using more than a single transmitter and is a big problem when using a dozen or more. And more RF flying around the room will sooner or later end up in your system as noise.

Set Up Antennas Correctly

Proper antenna set up can result in free benefits, so don’t ignore it! Omni antennas, such as the whips that are provided with a new wireless microphone, pick up in a 360° horizontal circle, so they cannot be aimed. They provide low gain and no rejection of local interference. Directional antennas (paddles and helicals) provide additional range and can typically reject 50% or more of local interference when correctly aimed.        

Use Antenna Distribution

Never heard of antenna distribution for wireless audio?  Or heard about it, but don't really know what it is?  Through countless conversations with our customers, we've discovered that many troublesome interference and dropout issues boil down to users with multiple wireless mics and no antenna distribution, or antenna distribution that is improperly deployed.  With a surprisingly large number of these conversations, adding proper distribution completely eliminates the interference and dropouts.

"We upgraded a 16 channel wireless mic system located next to a College radio station.   The system had a lot of problems before we put in the RF Venue DISTRO4 system and now it’s like a whole new system with no problems."  - Audio Visual One

Use Good Coaxial Cabling

In a wireless microphone system, every item from the antenna to the connectors to the cabling matters significantly.  Taken together, they can be the difference between success and failure.  One of the primary places systems fail or degrade over time is in the coaxial cables that connect your antennas to your antenna distribution, and the cables that connect your distribution system to your wireless mic receivers.  Always use good quality low loss, double shielded 50 ohm cable with your wireless system.  Unless it's permanently installed, you'll also want to check and change those cables over time, more so if they are frequently handled.

Fine Tune Your System

RF Spectrum conditions are dynamic and operating a wireless microphone system during a live event and an hour before a live event can be two very different things.  Monitoring and upgrading your wireless system over time is the best way to avoid signal dropouts and interference.  Simple plug and play tools such as RF bandpass filters serve to eliminate interference from wreaking havoc in your mic system.  And further fine tuning your system with more specialized antennas, placement, and other simple techniques, your wireless mics can work in even the most unpredictable environments!   Check out this 90-Second live RF demonstration from a busy convention floor