Taming The RF Beast

Another notable innovation is Lectrosonics Digital Hybrid Wireless technology, which utilizes a proprietary algorithm to encode the digital audio information into an analog format, which is then transmitted over an analog FM wireless link.

The receiver employs high-end filters, RF amplifiers, mixers and detector to capture the encoded signal and a DSP recovers the original digital audio. This hybrid approach enhances immunity to noise without compromising spectral and power efficiency, as well as operating range.

Lectrosonics Venue receivers also work in tandem with System Designer software that includes a spectrum scanner providing a visual display of RF activity within the tuning range of the system to quickly locate clear operating frequencies. In addition, a walk test recorder generates a visual of RF levels during a walk test of a project site.

Frequency-agile systems that can detect problems and automatically (and seamlessly) switch both transmitter and receiver to another (open) frequency represent another effective approach. The new System 10 Pro wireless from Audio-Technica (subject of a recent Road Test here) is a good example. The receiver and transmitter are actually transceivers that are constantly communicating with one another. If interference occurs, the units switch over to a clear frequency without a hitch.

Lectrosonics System Designer software that includes a spectrum scanner, walk test recorder and more.

Further Options
One way to avoid a lot of the headaches in the UHF band is to operate outside of it. Many years ago most (if not all) wireless microphones operated in the VHF (TV band channels 2-13) spectrum from 150-216 MHz. My company still has a few VHF systems that work quite well because the spectrum is pretty empty.

Radio Active Designs (RAD) recently introduced the UV-1G wireless intercom system, which can help in crowded UHF environments. The system offers up to 30 base stations and 180 belt packs in the same footprint as one base station and four belt packs that use traditional FM technology. And the belt packs operate in the VHF band, freeing up valuable UHF spectrum for wireless microphones and IEMs. The system uses proprietary Enhanced Narrow Band technology, a unique modulation scheme that is more spectrally efficient than current FM (Frequency Modulation) technology. Each channel in a UV-1G system has an occupied bandwidth of only 25 kHz.

Several wireless manufacturers also offer systems that operate in the 2.4 GHz band, most commonly used by Wi-Fi. While it’s certainly true that there’s a lot of activity within the 2.4 GHz range, manufacturers have developed ways to make it work, including the aforementioned System 10 Pro that uses frequency agility to switch frequencies.

A Sennheiser evolution wireless D1 instrument system.

The Line 6 XD-V70 was an early professional caliber wireless system operating in the 2.4 GHz band. The system has proprietary technology called Digital Channel Lock (DCL) that distinguishes its own digital audio from any other third-party signal, including Wi-Fi. Up to 12 XD-V70 systems can operate in the band simultaneously, while the newer XD-V75 allows up to 14 systems.

The Sennheiser evolution wireless D1 is a recent addition to the 2.4 GHz club, with transmitters and receivers that automatically pair and select suitable transmission frequencies, while multiple D1 systems can automatically coordinate themselves.

Systems are also coming on the scene that operate in the 1.9 GHz range, such as the recently released Sennheiser SpeechLine Digital Wireless system with Automatic Frequency Management technology that searches and can switch to a clear frequency if transmission is disturbed. In addition, network integration enables the system status to be remote controlled and monitored using the Wireless System Remote (WSR) app, AMX or Crestron.