Lectrosonics WM Watertight Belt-Pack Transmitter with Lavalier Mic (Block 20: 512.000 - 537.500 MHz)

The WM Watertight Belt-Pack Transmitter with Lavalier Mic from Lectrosonics is designed for wet or dusty environments. It features an O-ring sealed battery compartment and input jack, a compression sealed antenna port, and a gasket sealed control panel and back cover. It can be used when paired with a wireless receiver for capturing audio in broadcast TV, ENG (Electronic Field Productions), and EFP (Electronic Field Production) applications, and more.

Dual AA batteries provide twice the operating time of earlier watertight transmitter designs and the larger membrane switches and control panel have a highly visible backlit LCD, which enhances the user interface. In addition, there are 50, 100, or 200 mW selectable-output power switches to maximize battery life and operating range.

Some other features include servo bias input circuitry with selectable voltage for compatibility with other microphones, and programmable compatibility mode for use with a wide variety of different receivers. The transmitter is enclosed in a machined-aluminum corrosion resistant housing and includes a Lectrosonics M152/WP omnidirectional lavalier mic, a belt clip, an O-Ring kit, and two AA lithium batteries.

Servo Bias Input

The voltage and current requirements of the wide variety of electret microphones used in professional applications has caused confusion and compromises in the wiring needed for wireless transmitters. To address this problem, the Servo Bias input circuit provides an automatically regulated voltage over a very wide range of current for compatibility with all microphones

Digital Hybrid Wireless Technology

All wireless links suffer from channel noise to some degree, and all wireless microphone systems seek to minimize the impact of that noise on the desired signal. Conventional analog systems use companders for enhanced dynamic range, at the cost of subtle artifacts (typically pumping and breathing ). Digital systems defeat the noise by sending the audio information in digital form, at the cost of some combination of power, bandwidth and resistance to interference

Digital Hybrid systems overcome channel noise by digitally encoding the audio in the transmitter and decoding it in the receiver, yet still sending the encoded information via an analog FM wireless link. This proprietary algorithm is not a digital implementation of an analog compander but a technique that can be accomplished only in the digital domain, even though the inputs and outputs are analog

No Pre-Emphasis/De-Emphasis

The Digital Hybrid design results in a signal-to-noise ratio high enough to preclude the need for conventional pre-emphasis (HF boost) in the transmitter and de-emphasis (HF roll off) in the receiver. This eliminates the potential for distortion of signals with abundant high-frequency information

Low Frequency Roll-Off

The low frequency roll-off can be set for a 3 dB down point at 35, 50, 70, 100, 120 and 150 Hz to control subsonic and very low frequency audio content in the audio. The actual roll-off frequency will vary slightly depending upon the low frequency response of the microphone.
Excessive low frequency content can drive the transmitter into limiting, or in the case of high output sound systems, it can even cause damage to loudspeaker systems. The roll-off is normally adjusted by ear while listening as the system is operating

Input Limiter

A DSP-controlled analog audio limiter is employed before the A-D converter. The limiter has a range of more than 30 dB for excellent overload protection. A dual release envelope makes the limiter acoustically transparent while maintaining low distortion. It can be thought of as two limiters in series, a fast attack and release limiter followed by a slow attack and release limiter. The limiter recovers quickly from brief transients, with no audible side effects, and also recovers slowly from sustained high levels to keep audio distortion low while preserving short term dynamics