Tech Focus: Bodypacks
In the world of bodypack transmitters, size still matters. The value of athlete audio and on-field sound continues to increase, putting a premium on devices small and light enough to not interfere with play but able to reliably reach a receiving antenna and to do so cost-effectively. Smaller, lighter, cheaper is the mantra.
But there are still plenty of other issues facing manufacturers. Most notable is the looming loss of RF spectrum as the FCC-controlled bandwidth auctions, scheduled for mid to late 2016, creep closer. Once the auctions have been completed and a 39-month infrastructure rebuilding period is through, bodypack manufacturers and users will be looking at significantly truncated usable spectrum, with much of the prized 600 MHz band — if not all of it — no longer routinely available.
Karl Winkler, VP of sales, Lectrosonics, whose bodypacks are used by the NFL and NHL, points to the company’s newest bodypack product, the Super Slim Mini, which has two-thirds the weight of its lightest existing unit, as a reaction to the physical demands on bodypacks now. But spectrum loss, he adds, was behind development of a new IFB system, which uses the VHF (174 MHz-216 MHz) part of the spectrum to free up UHF bandwidth for audio to be used on the air.
“What’s happening is that we’re moving the comms audio into VHF in order to leave more room in the UHF range for what people will hear at home,” he explains. “Spectrum loss is making us make better use of what will be left.”
Encryption has also taken on new levels of importance. As on-field communications have increased, so has what seems to be opposing teams’ desire to listen in. Allegations of eavesdropping against the New England Patriots and the New Orleans Saints in the last dozen years have underscored the pursuit of ever higher levels of protection for wireless communications.
Encryption strength is constantly improving, Winkler says, with 256-bit AES encryption now the gold standard for the industry. “Key length and key management are the main points when it comes to encryption,” he says, referring to the encryption algorithm established by the U.S. National Institute of Standards and Technology (NIST) in 2001.
Such features as enhanced spectral efficiency and higher-resolution digital audio will also be migrating onto the playing field, opines Stephen Kohler, senior director of marketing, Shure, whose wireless microphone systems are widely used by on-air talent at sports events. “It’s all about improving the consumer experience, and that leads back to the bodypack or the transmitter in the helmet.”
Despite the challenges of spectrum constriction, compact bodypacks will only grow in demand as new sports add athlete audio to their broadcasts. Quantum5X, whose PlayerMics have been on NBA players for years, has been working with rugby teams in the UK and Australia, as well as with at least one MLS team in the U.S., the Philadelphia Union, according to CEO Paul Johnson. Rugby, he notes, is using a variant of the PlayerMic worn between the player’s shoulder blades and kept in place with a compression vest. NBA players wear them in pockets on the side of their jerseys.
“The thing with sports that don’t use padding is that the transmitter has to be very small but also has to be designed to avoid injuring the player if he falls on it or is tackled near it,” Johnson explains. “Player safety is the big issue.”
He notes that the bodypack’s strain-release connectors and flexible housing are designed to achieve that goal but stresses that the flexible-housing design is intended to keep the device transmitting.
The housings for bodypacks used by rugby and soccer are slightly larger than those for basketball, to accommodate a larger battery with longer running time. The MLS versions are also the first to use transmitters that operate in the 500 MHz range, the leading edge of Quantum5X’s long-range strategy to move its entire product line into that frequency range, in anticipation of the loss of the 600 MHz band. These bodypacks house an antenna whose length has increased by about 1 in., needed to accommodate the lower frequency range.
“We’re relaunching the entire product line around that now,” Johnson says.
A Local Issue, for Now
Accommodating reallocated RF spectrum will be a U.S. problem for the foreseeable future, according to Joe Ciaudelli, director of spectrum affairs, Sennheiser. He was recently a member of the U.S. Department of State’s delegation to the World Radio Conference in Geneva. There, European and national broadcast agencies rejected the U.S. initiative to reallocate UHF spectrum to mobile devices. The quadrennial conclave won’t take the matter up again until 2023, he says, and, even if it did, implementation would keep the 600 MHz band there safe at least until 2027.
In the upcoming, reallocated U.S. RF landscape, Ciaudelli says, wireless users will be working in the 500 MHz range, along with some of the carved-out remainders of 600 MHz, in that range’s guard bands and duplex gap. However, he adds, wireless will also be moving upwards, into the 900 MHZ and 1.4 GHz ranges, which the FCC has cleared for professional use. There, he says, users will have to learn a few new tricks.
“As you go up in frequency, not only does propagation diminish, but body absorption of radio waves really increases,” he explains, further reducing RF reach. Best practices to counter that include ensuring that no part of the antenna comes into contact with the body or with sweat-dampened clothing — not an easy task in sports.
Bodypacks’ importance in broadcast-sports audio will increase at the same time that the technical challenges are also growing. Break out the popcorn: this will be an interesting narrative to follow.
Rounding up coverage of RF bodypack audio transmitters is a selection of some current models.
The AEW-T1000a UniPak features an LCD display, soft-touch controls, and field-replaceable helical and flexible-wire antennas. It has a four-pin locking connector and offers both low- and high-impedance inputs plus a bias connection, for use with dynamic and electret condenser microphones as well as Hi-Z instrument pickups. Switchable RF power provides eight hours of battery life in the high (35-mW) setting and 10 hours in the low (10-mW) setting (two AA alkaline). A three-position sliding control cover prevents accidental shut-off/channel-switching. www.audio-technica.com
The WTU-2 compact metal bodypack solution for the RE-2 system is automatically compatible with the Telex RSB-2 mute switch for football applications. It features selectable RF output power and rechargeable-AA-battery operation with optional BH-200 charger and is compatible with RSB-2 referee mute switch.
The BPU-2 compact bodypack transmitter for the RE-2 wireless system is made of high-impact ABS plastic. The single on/off switch also functions as a mute, and the TA4 microphone connector is compatible with any EV lapel and head-worn microphone, including the RE97Tx and RE97-2-Tx. Other features include a “cellphone” rotating belt clip and a smart battery. www.electrovoice.com
The SSM (Super Slight Micro) Digital Hybrid Wireless micro transmitter tunes across 76.8 MHz or three standard Lectrosonics frequency blocks, features power settings at 25- or 50-mW RF power, and runs on a rechargeable lithium-ion battery. Measuring 2.52 x 1.48 x 0.57 in. and weighing 2.3 oz., including battery, the SSM responds to RM remote commands, compatible with the Lectro RM smartphone app. Frequency bands offered are A1 (470-537 MHz), B1 (537-614 MHz), C1 (614-691 MHz), and D1 (691-767 MHz, export only).
The SMV Series brings Lectrosonics’ Digital Hybrid Wireless technology to miniature transmitters in two configurations: the SMV for the smallest size and the SMQV for longer battery life. Both units incorporate a servo-bias input to accommodate a wide variety of electret lavaliere or head-worn microphones. Two bicolor LEDs indicate input levels for proper modulation. Both units feature backlit LCDs and metal housings milled from billet stock for maximum durability. Both units offer RF power settings at 50, 100, and 250 mW. The SMV Series units respond to RM remote commands, compatible with the Lectro RM smartphone app, and are offered with 256 synthesized UHF frequencies in 100-kHz steps in nine blocks, each covering a 25.6-MHz bandwidth.
The WM is a water-resistant transmitter with a membrane keypad and a specially designed machined-aluminum housing. The WM offers 256 synthesized UHF frequencies in 100-kHz steps in nine blocks, each covering a 25.6 MHz bandwidth. Features include selectable RF power at 50, 100, and 250 mW; dual bicolor modulation LEDs for accurate gain adjustment; and a backlit LCD for ease of use. The WM is powered by two AA batteries, with internal switching power supplies providing constant voltages to the transmitter circuits from the beginning (1.5 V) to the end (0.85 V) of battery life. The WM responds to RM remote commands, compatible with the Lectro RM smartphone app, for hands-free setting changes. www.lectrosonics.com
Replacing the QT-256, the new QT-300 is available in three models: QT-300 BeltPack, QT-300 PlayerMic, and QT-300 AquaMic. Its transmitters are preset to 90-mW output power; other power levels from 10 mW up to 200 mW are available on special order from the factory. Mic gain is adjustable as well. The standard QT-300 enclosure is milled from industrial-grade aluminum and is the size of two AA batteries. The QT-300 AquaMic is a fully waterproof transmitter. Measuring 4.3 x 1.5 x 0.4 in., the QT-300 PlayerMic comes in a flexible, sweat-proof polymer enclosure and is offered with a detachable or hard-wired lavaliere microphone. The QT-300s are wideband from 525 MHz to 598 MHz and are manually adjustable in 25-kHz steps with 3,000 selectable channels.
The QT-5100 wideband, remotely controllable transmitter covers 525 MHz-598 MHz with 3,000 selectable channels in 25-kHz steps. Currently, there are five models of QT-5100: QT-5100 Incognito, QT-5100 AquaMic, QT-5100 RefMic (new for 2016 with integrated non-popping audio-mute switch), QT-5100 PlayerMic, and QT-5100 PlayerMic S. The two models of PlayerMic are the regular size, and, new for 2016, the S model, Q5X’s smallest remote-controlled PlayerMic to date.
The QT-5100 PlayerMic S is a new design for the NBA. Measuring 3 x 1.5 x 0.4 in., it’s 35% smaller than Q5X’s previous version and the smallest remote-controlled PlayerMic to date, featuring a soft, tough polymer enclosure.
The RCAS (Remote Control Audio System) used in the QT-5100 series enables remote operation of a variety of functions: on/off, RF frequency, RF power, mic gain, mute, groupings, and compatibility modes; it also monitors transmitter-telemetry RSSI status and battery level. The RCAS can manage transmitter function through a laptop or through the QG-H1 handheld ccontroller. Since the RCAS is RF-based, it allows transmitter settings to be changed through uniforms and over relatively long distances without interfering with the athletes or on-air talent.
Every Q5X transmitter uses the latest lithium-ion–battery technology to maintain a green environment while providing four to 15 hours of runtime (depending on battery size and transmitter power) on a single charge. With the ability to charge from any standard USB charger or auxiliary battery packs, these transmitters are the ultimate green solution. www.q5x.com
The BTR-240 bodypack uses license-free 2.4 GHz technology and offers multi-level security and audio encryption, ClearScan channel selection, a choice of two independent or simultaneous audio channels, eight full-duplex beltpacks or a virtually unlimited number of half-duplex beltpacks, an easy-to-read LCD display, two- and four-wire wired intercom interfaces, XLR in/out for interfacing with general audio systems, auto-select for condenser or dynamic microphones, and wired or wireless TR-240 beltpack operation. www.rtsintercoms.com
SK 9000 is a high-resolution, fully uncompressed digital wireless beltpack transmitter, compatible with three-pin Lemo-connector lavaliere microphones. Instruments with line signal and guitars benefit from the cable-like audio transmission. The housing of the SK 9000 is made of die-cast magnesium to offer maximum robustness at a very low weight. The user interface features an icon-based menu structure and infrared synchronization with the receiver. Exchangeable energy packs with environment-friendly lithium-ion technology supply the required energy while saving thousands of batteries over time. The SK 9000 is compatible with the flagship EM 9046 digital wireless mainframe, which accommodates up to eight receiver channels.
SK 5212-II ultra-compact bodypack uses one AA battery and offers transmission over a switching bandwidth of up to 184 MHz in 5-kHz steps. The SK 5212-II features switchable output power of 10/50 mW, plus a low-intermodulation power mode that increases the linear headroom of the amplifier, allowing users to squeeze more channels into a crowded RF environment. Other features include HiDyn Plus noise reduction, backlit LC display, adjustable audio sensitivity in 1-dB steps from –30 to +40 dB, and a switchable low-cut filter. The wide switching bandwidth of the SK 5212-II matches Sennheiser’s EM 3732-II true-diversity receiver but is also compatible with all 3000 and 5000 Series receivers.
The SK 250 beltpack transmitter offers a maximum 250-mW RF output power, quick-exchange battery or rechargeable pack, 16 switchable frequencies, and HiDyn Plus noise reduction. It is compatible with the EK 3241 slot-mount diversity receiver as well as with all 3000 and 5000 Series receivers.
The SK 2000 bodypack transmitter offers up to 75 MHz of switching bandwidth in 25-kHz steps, frequency response of 25 Hz to 20,000 Hz, plus full compatibility with Evolution Wireless systems. The SK 2000 offers selectable output power (10/30/50 mW), allowing users to increase power for longer transmission ranges or reduce power to squeeze more channels into a tight frequency range. For long-range applications, the SK 2000 XP (U.S. version) includes an additional 100-mW output-power mode. An optional rechargeable-battery pack can be charged in the unit using the external charging contacts. Other features include 20 fixed frequency banks with up to 64 compatible presets each, six banks with 64 user-tunable channels, and a pilot-tone squelch for interference-free operation. The SK 2000 is compatible with the 2000 Series’ EM 2000 and EM 2050 receivers, all Evolution Wireless receivers, and the EM 3732-II diversity receiver (with HDX compander activated). www.sennheiser.com
The QLX-D digital wireless delivers transparent 24-bit transparent audio quality with outstanding spectrum efficiency and signal stability. It offers rugged, metal handheld and bodypack transmitters with a half-rack receiver. Its feature set includes AES256 encryption, IP networking for use with Wireless Workbench 6 software, ShurePlus Channels mobile app for iOS, and AMX/Crestron devices, along with the option to use Shure’s intelligent rechargeable-battery technology. QLX-D features many of the benefits of Shure’s high-tier ULX-D line, including outstanding audio quality. Meanwhile, ULX-D enjoys more RF flexibility, including high-density mode and higher transmitter RF output option. ULX-D provides sophisticated network capability so the receiver can be monitored across a subnet by third-party devices. ULX-D also offers dual and quad receivers with such features as Dante digital-audio networking, integrated Ethernet switch, frequency diversity, audio summing, and simplified hardware setup. www.shure.com
The TRX series digital wireless microphones feature patented internal backup recording with timecode and RF remote-control reception. Other features include 100%-digital modulation, digital dropout protection, five- to nine-hour running time (depending on model), OLED graphic display, and no intermodulation; up to 50 transmitters in the same frequency block can be used simultaneously. Timecode transmission and reception can also be distributed through ZaxNet, Zaxcom’s 2.4-GHz signal network, to other transmitters and receivers, keeping the entire workflow in perfect timecode sync. www.zaxcom.com