Question: How do I transmit wireless audio for drive-in style services or concerts?
Answer: This year has been one of finding new ways to accomplish things we have done in certain ways for so long. Congregating in houses of worship or gathering by the thousands for concerts are examples of events we have needed to do differently. Some people have taken to hosting these events online with popular streaming services, but others have utilized low-powered FM transmitters to send the signal to those parked close by in their cars. Drive-in movie theaters have used this technology for some time, and now, after falling “out of style” some years back, this setup is becoming a popular choice again. While we are currently socially distancing, we can take this solution with us into the future and create a new way of attending various events.
When thinking about sending out a wireless signal, we must understand a few basics of wireless systems. First, a transmitter is the device that sends the wireless signal into the air on a particular frequency. Next, a receiver may be tuned to the same frequency the transmitter is sending out to pick up the sent signal. As we want multiple people to be able to pick up this signal, using an analog transmission allows any number of receiving devices to tune in and pick up the transmitted signal. Most people have access to an FM receiver, as most cars and portable devices still have that technology readily available for consumer use. Wireless microphone systems on the other hand, like Audio-Technica’s 3000 Series or System 10, operate on frequency ranges that most people can’t access with receivers they already have. Using an FM radio signal transmission allows for almost anyone to pick up the sent signal.
Some FM transmitters have the ability to operate at different transmit powers. A higher transmit power will give you more range, but may require an FCC license to operate (you can be fined for transmitting illegally). Operating at a low transmit power is often fine in most applications. Using a low transmit power will still allow you to get your signal a few hundred feet out to the parking lot of a house of worship or drive-in theater. Be certain to check with the FM transmitter manufacturer on their specifications to determine if it will fit your application needs. An FM transmitter (such as the Rolls HR70) will have an audio input, likely a LINE level stereo input, while some may offer an input that lets you plug a microphone directly into it. These inputs will allow you to send your full stereo audio signal or single microphone signal over the FM transmission. By using your car radio’s receiver, you can find an unoccupied FM frequency between 88 and 108 MHz in the location you are going to use the system, and determine which frequencies will cause you the least amount of potential interference. Additionally, you may use an RF analyzer such as the RF Explorer® Pro Audio Edition to survey the RF spectrum prior to setup.
Like all wireless systems, FM transmitters are best used with a line of sight operation. Using the FM Antenna Kit from RF Venue will allow you to improve the coverage of the transmitted signal out to the car stereos. The kit includes a 100' RG8X BNC antenna cable to connect the antenna to your FM transmitter antenna input. Additionally, a telescoping antenna stand is included along with a sandbag to prevent the stand from being knocked over.
If you have further questions on setting up an FM wireless system to send out your audio signal to those nearby, please contact the Audio-Technica Audio Solutions Department.