Demystifying On-Camera Wireless Systems
Whether you are a student, independent filmmaker, production company, or video journalist, wireless miking is an invaluable technique, and in many cases, one that you simply cannot do without. While shotgun mics will always have an important place in audio for film, the ability to close-mic a subject can allow for clearer dialog capture and reduce the needed instances of automated dialog replacement (ADR) in post. However, as integral and important as on-camera wireless systems have become, they have managed to maintain a somewhat intimidating reputation, one that we can hopefully demystify. By examining the basic functions of some different available systems, you will be able to determine what will best suit your personal idiom.
VHF Versus UHF
One of the first things you need to address when talking about wireless microphones systems is very high frequency (VHF) and ultra high frequency (UHF), and what the difference is between the two. VHF is a broad frequency range in which many “everyday” wireless systems operate, including walkie-talkies, cordless phones, and radio broadcasts, to name a few. A small chunk of the VHF frequency range is dedicated for use by wireless microphone systems.
As its name implies, UHF systems broadcast and receive on much higher frequencies than their VHF counterparts. Since higher frequencies mean smaller wavelengths, one of the benefits of UHF systems is the ability to use shorter antennas. Because these shorter wavelengths aren’t exactly efficient at traveling distances, many UHF systems have more powerful transmitter power and operate best when the receiver and transmitter are within each other's line of sight.
Both VHF and UHF wireless systems have channels on which they operate. Some systems have a set, single channel, while many more modern systems come with multiple channels you can select, to help avoid interference. Generally, the more channels to which a system can be tuned, the better, as multiple channels provide more opportunities for interference-free broadcast.
Variety of Systems
With some basic concepts explained, let us take a look at how some different systems implement them, along with other features. Please see below for a breakdown of available system configurations.
The Audio Technica Pro 88 series wireless systems fall into the entry-level category for on-camera wireless systems, and is ideal for film students needing a wireless rig or someone looking for an inexpensive back-up system. The Pro 88 systems are VHF and available as a two-piece system (one bodypack transmitter and one on-camera receiver) with either an omnidirectional or cardioid lavalier microphone. With the Pro 88, you have two switchable frequencies and a functional operating range that will work well over short distances. Both the transmitter and receiver are powered by 9-volt batteries that give the system up to 8 hours of operation. This gives you a decent amount of time to record before you need to swap batteries; however, the downside is that you will be using regular 9-volts or investing in your own rechargeable battery system. Audio Technica includes an earphone for monitoring the receiver.
Samson’s AirLine Micro Camera System operates on UHF but unlike the Pro 88, has a set channel assignment, meaning the receiver and transmitter can only be tuned to one frequency. Consisting of a bodypack transmitter, a receiver, and an omnidirectional lavalier microphone, the system is clearly designed for ease of use. The AirLine’s bodypack transmitter has a single multi-function switch that acts as a power button, mute switch, and volume control. Since its channel is preset, you can simply turn both units on, set your volume levels, and be ready to roll. Both the transmitter and receiver have built-in rechargeable batteries that will provide between 7 or 8 hours of use on a charge. While this will save you money buying batteries, the feature is a double-edged sword, as there is no way to swap the batteries out when they need recharging. Samson includes a recharging dock, USB charging cables, a hot-shoe mount for connecting the receiver to your camera, a 3.5mm cable, a 3.5mm-to-XLR cable, an AC adapter, and a system carry case.
If you are in a city with a great deal of radio-frequency traffic (for example, multiple radio and broadcast TV stations, police-radio traffic), you are going to be better served by a system that has multiple channels to select to help avoid interference. The Azden 105 Series is UHF and boasts up to 92 user-selectable channels. This channel count will prove itself beneficial for interference-free operation. One of the benefits of the 105 series is the versatility in its components. You can get a system with a bodypack transmitter and lavalier mic, awireless handheld mic, or a plug-on transmitter for using your own XLR handheld mic. All of the transmitter and receiver options are powered by 2 AA batteries, for between 6 and 8 hours of operation.
Sony’s UWP series starts bringing in some “pro” level features on a bit more of a budget, allowing you to use the systems in some more demanding scenarios. The UWP lineup is really the first place you should start looking if you need a system you can rely on for professional gigs. With up to 188 selectable channels, you can not only avoid interference from outside sources, but use multiple systems side by side simultaneously (depending on interference conditions, of course). The UWP lineup is available in a number of transmitter/receiver configurations including abodypack with omnidirectional lavalier mic, a handheld mic, or with a plug-on transmitter and bodypack transmitter. Regardless of transmitter choice, the UWP series systems have lightweight metal construction and are designed for rugged day-to-day use in the field. UWP series receivers also have dual antennas to allow for diversity reception, reducing transmission dropouts.
The FP Series from Shure introduces some versatility as well as a number of features designed for easy setup and operation. In ideal conditions, up to 20 systems can be used simultaneously. The receivers in the FP line have Shure’s Automatic Frequency Selection, which automatically scans for the clearest available channel, while the Automatic Transmitter Setup feature, as its name implies, syncs the transmitter to the frequency to which the receiver has been set. It is available in numerous configurations, including abodypack with lavalier mic, with a plug-on transmitter, or with ahandheld transmitter. An added benefit of the handheld transmitter is its compatibility with Shure’s lineup of swappable microphone capsules, including the venerableSM58.
Looking at the Evolution Wireless G3 series from Sennheiser, the line between a “consumer” price point and “pro” results really begins to blur. Boasting 1,680 switchable frequencies, the G3 provides a vast number of channels to select for clear transmission. It uses Sennheiser’s frequency scan function to help you navigate through the available channels and land on one that has the least amount of interference, streamlining setup and assuring you can take full advantage of the broad swath of available frequencies. The system supports a broad frequency response for wireless (from 25Hz to 18kHz), allowing for pristine and accurate transmission with very little fidelity loss. While the receiver appears to have only one antenna, it actually has a second one integrated into its body design, allowing for true diversity reception. The transmitters in the G3 series provide up to 30 mW of output RF power, which helps provide a consistent signal and range of operation while in use.
Wireless miking is an established necessity for a wide variety of film applications. While there is a tremendous number of options available that run the price-range gamut, there is no reason to be daunted.