Used Lectrosonics WM E Belt-Pack Transmitter, Block 19

Designed for wet or dusty environments, the WM transmitter features O-ring sealed battery compartments and input jack, a compression sealed antenna port and gasket sealed control panel and back cover. Dual AA batteries provide twice the operating time of earlier watertight transmitter designs. Larger membrane switches and control panel and a highly visible, backlit LCD enhance the user interface.

The WM is offered with M152WP Lav Microphone or as an upgrade, with the Voice Technologies VT500 Water Lav Microphone

• Selectable output power to maximize battery life or operating range (50, 100 or 250 mW)
• Machined aluminum, corrosion resistant housing
• Water resistant seals for use in wet environments
• LCD interface with lockout option
• Programmable compatibility modes for use with a wide variety of different receivers
• Servo Bias input circuitry with selectable voltage

To meet the demand for both extended operating range and extended battery life, the transmitter offers selectable output power of 50, 100 and 250 mW. With higher power output, the operating range is improved at the expense of battery life. When range is not an issue, the power can be reduced to extend the battery life.

The transmitter can be controlled by the RM and RM2 remote control units for hands free setup and adjustment using audible tones delivered into the microphone from a tiny loudspeaker in the remote control unit. The transmitter can be put to sleep to conserve battery power during setup when it is buried deep inside costuming, then awakened for normal operation when the production begins. Other adjustments include frequency, audio level and control panel lockout.

The DSP-based design works with all Digital Hybrid receivers and is backward compatible for use with Lectrosonics 200 and 100 Series and IFB receivers and some other brands of analog wireless receivers. The input section features servo bias circuitry with voltages being selectable from the LCD to match the requirements of a wide variety of lavaliere microphones. The bias can also be turned off for use with dynamic microphones. A line level setting is provided for use with signal levels up to 5 volts. The low frequency roll-off can be adjusted from 35 to 150 Hz.

A DSP-controlled analog audio limiter is employed ahead of the first mic preamp to protect the entire audio chain from overload. The limiter has a range of more than 30 dB for excellent overload protection and a dual release envelope that makes the limiter acoustically transparent while maintaining low distortion.

Watertight Connections

The input connector is mounted in a recessed opening which provides a captive seat for the O-ring on the microphone connector. This captures the O-ring allowing it to be tightened firmly. The antenna is mounted with a compressible strain relief under a flange that presses the strain relief into a tapered opening for a watertight connection.

Input Limiter

A DSP-controlled analog audio limiter is employed before the analog-to-digital 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. The limiter recovers quickly from brief transients, so that its action is hidden from the listener, but recovers slowly from sustained high levels, to keep audio distortion low and preserve short term dynamic changes. The bicolor LEDs on the control panel indicate limiter activity accurately to assist in setting the input gain for optimal signal to noise ratio and dynamic range.

DSP-Based Pilot Tone & Compatibility

The DSP generated pilot tone eliminates the need for fragile crystals and allows a different pilot tone frequency for each of the 256 carrier frequencies in the tuning range of the wireless system. Individual pilot tones significantly reduce squelch problems in multichannel systems where a pilot tone signal can appear in the wrong receiver via intermodulation products. The DSP also offers compatibility modes to allow backward compatibility with all Lectrosonics IFB systems, 100/200 Series systems and analog receivers from some other manufacturers in addition to its native Digital Hybrid operating mode.

Output Isolator

The transmitter RF output circuit includes a specialized RF device called an isolator using a magnetically polarized ferrite to allow RF signals to pass through to the antenna, but block them from coming backward into the transmitter output section. The isolator greatly reduces RF intermodulation produced in the transmitter output stages when multiple units are used in close proximity (a few feet apart). The isolator also helps protect the output stage from electrostatic shock delivered to the antenna. Isolators are common in broadcast and commercial applications, but because of their high cost it is unusual to find them in wireless microphone transmitters.

LectroRM

By New Endian LLC
LectroRM is a mobile application for iOS and Android operating systems. Its purpose is to remotely control Lectrosonics Transmitters, including:
• SM Series
• WM
• L Series
The app remotely changes settings on the transmitter through the use of encoded audio tones, which when received by the attached microphone, will alter the configured setting. The app was released by New Endian, LLC in September 2011. The app is available for download and sells on the Apple App Store and Google Play Store. LectroRM's remote control mechanism is the use of an audio sequence of tones (dweedles) that are interpreted by the transmitter as a configuration change. The settings available in LectroRM are:
• Audio Level
• Frequency
• Sleep Mode
• Lock Mode

User Interface

The user interface involves selecting the audio sequence related to the desired change. Each version has an interface for selecting the desired setting and the desired option for that setting. Each version also has a mechanism to prevent accidental activation of the tone.

iOS
The iPhone version keeps each available setting on a separate page with the list of options for that setting. On iOS, the "Activate" toggle switch must be enabled to show the button which will then activate the audio. The iOS version's default orientation is upside-down but can be configured to orient right-side up. The purpose for this is to orient the device's speaker, which is at the bottom of the device, closer to the transmitter microphone.

Android
The Android version keeps all settings on the same page and allows the user to toggle between the activation buttons for each setting. The activation button must be long pressed to activate. The Android version also allows users to keep a configurable list of full sets of settings.

Activation

For a transmitter to respond to remote control audio tones, the transmitter must meet certain requirements:
• The transmitter must not be turned off; it can however be in sleep mode.
• The transmitter must have firmware version 1.5 or later for Audio, Frequency, Sleep and Lock changes.
• The transmitter microphone must be within range.
• The transmitter must be configured to enable remote control activation