Recently, I spent a few hours at the Shubert Theater in New York City learning about and listening to Shure’s new Axient wireless system. Officially referred to as a “wireless management network,” it’s a forward-thinking system that incorporates Shure’s latest innovations in wireless technology. As such, I thought it would be interesting to share what I learned about the challenges of wireless operations in the crowded RF world and examine some of the technology behind this advanced product.
When I think of a wireless system, I am reminded of the obvious ones: Madonna onstage with a headset mic, Slash running around with his guitar or even Tommy Lee spinning upside down in his drum kit while still doing background vocals. What you might not consider are the headaches involved with having 25 wireless mics onstage at a huge Broadway show, a dozen open mics at a late-night national television performance or even just a few mics at a local church or school play. What do they all have in common, aside from “no cables?” They must be failsafe during the show, sound great and have a long battery life, but also should not suffer from dropouts and interference caused by an ever-crowded market of competing wireless signals.
Something that we “wired” folks don’t have to worry about is the intense competition for the same spectrum of allocated wireless frequencies. Throw in government regulations and regulatory changes, broadband internet, the potential addition of millions of handheld smartphones, digital television and unknown future products, and you realize how big a challenge this is. However, Shure has pulled a few tricks out of its sleeve to deal with these problems with its Axient system.
The AXT400 dual-channel receiver, AXT100 bodypack transmitter and AXT handheld transmitter can deliver a package that provide onscreen alerts when interference is detected and move to a clear frequency in a few milliseconds. The AXT 400’s interference-detection circuitry will also discover even the smallest changes in RF signal quality and, when warned, allow the engineer to manually move to the chosen backup frequency. It also features ShowLink Remote control for real-time wireless transmitter adjustments of things like frequency assignments, RF mute enabling and RF power output changes. It has advanced squelch suppression so that the system will never spit white noise out into the room, something I heard demonstrated onstage at the Shubert. Also, with the AXT610 ShowLink Access Point, you can have a wireless network connection between linked transmitters and receivers (up to 16), allowing for real-time network control over wider coverage areas. You can control even more transmitters by adding more Access Points.
PAR Technology Glossary- SHURE AXIENT
BODYPACK: A compact wireless transmitter worn on the user’s clothing or concealed under a costume
DUAL CHANNEL: Two independent receivers in one chassis, which share a common antenna and power connection
FREQUENCY DIVERSITY: Transmitting the same audio signal on two different frequencies at the same time, so that if one frequency is interfered with, the audio signal is still present on the other
IMD: Intermodulation distortion; the phenomenon by which two transmitters on different frequencies can cause interference for a transmitter on a third frequency
LINKED TRANSMITTERS AND RECEIVERS: A transmitter and receiver that can make coordinated frequency changes as a pair
RF: Radio frequency energy
SQUELCH: A circuit that mutes the receiver’s audio output when the radio signal is briefly interrupted; prevents bursts of noise or static from being heard
ZIGBEE: An IEEE standard for Personal Area Networks, which allows the short-range transmission of data.
[*All terms are defined in reference to the Axient system by Shure engineers and developers. — Ed.]
With the AXT600 Spectrum Manager, the backup frequency assignments mentioned above can be made automatically. The 1U Spectrum Manager does wideband UHF spectrum scanning and frequency coordination and will help deliver critical information for allocating the best available frequencies to the relevant channels. Additional system components include the AXT620 Ethernet Switch, a 9-port switch for networking Axiom Systems; the AXT630 Antenna Distribution System for extra RF protection and optimal performance; and the AXT900 Rack Mount Charging Station for tour-ready battery charging and battery health information. There are also a variety of bodypack and handheld charging modules, batteries and so on.
Last but not least is something called Wireless Workbench 6 for Windows and MAC OSX. This event planning and control software was developed with the Axient system and allows for comprehensive system coordination, monitoring and control … all from a laptop. There are many other small but important details that help define this system, such as the ability to simultaneously transmit on two independent frequencies, the inclusion of analog FM technology for super-low latency, 40 to 18 kHz frequency response and even batteries with onboard microchips able to display accuracy to within 15 minutes of remaining life. Overall, I was highly impressed with the deep passion that the Shure engineers and their development team had about this product, and the end result shows. It’s obvious that the Axient is a highly intelligent, well thought out system, ready to tackle anything from a fullblown tour at Madison Square Garden to a Madison, Wisconsin town meeting.
Rich Tozzoli is a producer/engineer, a composer and the software editor for PAR.