Lectrosonics’ New Wireless Link System Uses ‘Wireless Hop’

By Dan Daley

Lectrosonics debuted its D4 Multichannel Digital Wireless Audio Link system at the 2009 NAB Show. It comprises the D4T digital transmitter and the D4R digital receiver, which shuttles four discrete audio channels over a range of up 1,200 ft. or more, using the license-free ISM 902-928 MHz band for freedom from DTV interference. Applications for the D4 system include video and film production, using a wireless hop from a bag system or cart back to a camera, audio-relay systems for installed sound, recording and mastering studios, and distributed loudspeaker systems.

These compact, portable units rely on a digital DQPSK (differential quadrature phase-shift keying) modulation scheme and a proprietary digital audio-encoding algorithm developed by Lectrosonics. Forward error correction is used to enhance range and reliability for the link. Diversity reception in the D4 is accomplished via dual receivers and artifact-free digital switching. Up to four D4 systems can be operated simultaneously on separate channels within the ISM band for a total of up to 16 audio channels in the same location. Also, 24-bit converters and a 48-kHz sample rate ensure that the audio quality meets or exceeds the demands for video, audio, or film production. Intelligent inputs allow for various sample-rate sources to be connected directly to the D4T.

Both the D4T digital transmitter and D4R digital receiver feature a large LCD for ease of setup and signal monitoring. Tactile switches on the front panel enable selection of programming and monitoring functions. Inputs and outputs for the D4 can be up to four AES/EBU digital or balanced analog inputs via TA3 mini XLR connectors on the back panel. Both units include a mini USB connector for future firmware upgrades. Key system specifications include a frequency response of 20 Hz to 20 kHz, ±0.5 dB; THD: 0.04% at 1 kHz, and the system’s dynamic range is greater than 104 dBA. Latency for the D4 is <1 ms for digital I/O. The D4 Multichannel Digital Wireless Audio Link system is expected to be available this month, pricing to be determined.

Also at the show, Lectrosonics introduced the Octopack receiver dock and antenna coupling system, which features slots for up to four Lectrosonics two-channel SRA or SRA5P Digital Hybrid Wireless receiver, offering up to eight wireless audio channels in a compact, portable configuration.

The front panel of the new Octopack accepts the SRA or SRA5P receivers and has BNC jacks for mounting whip antennas or coaxial cable for remote antennas. Eight individual RF cables with SMA connectors mate to the receivers, enabling diversity reception to be maintained for all four receivers. The master power switch and indicator lamp are also located on the front panel, along with a switch for antenna powering when remote RF boosters are used. Eight balanced mini-XLR audio outputs reside on the left panel. Lectrosonics’ new Octopack can be powered by external DC of 6-18V or by two optional L-style rechargeable battery packs, which can attach and lock onto the rear of the unit.

Pricing for the Lectrosonics Octopack receiver dock and antenna coupling system has not yet been determined. The Octopack is expected to be available in June.

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