The wireless microphone system shall operate in the UHF band and provide a tone key (32,768 kHz) to in-crease reliability and to minimize unwanted noise. The system shall allow to change the operating frequency in 25 kHz steps in order to avoid RF interference, enabling up to 47 systems to operate simultaneously in one frequency band. Preconfigured group, channel and frequency setups shall be available to ensure that mul-tiple systems in use do not interfere with one another. Additionally multiple free programmable frequency groups shall allow to create customized setups. An IR synchronization between receiver and transmitter for fast setup shall be implemented. The receiver shall have an user programmable menu-driven LC display showing group, channel, frequency, name, output level, squelch level, and lock status as well as the most important transmitter settings. It shall use technology such as MARCAD® signal combining circuitry for improved reception, minimized signal drop-outs, and the best possible signal-to-noise ratio. Tone key squelch, and noise squelch circuitry shall be im-plemented to provide optimal sound quality and mini-mize unwanted noise. The receiver shall include an RF meter for each antenna, an audio level meter, and net-working interface connectors for PC control and moni-toring. The receiver shall have a volume control and an adjustable noise squelch control. RF Carrier Frequency Range: 518 – 865 MHz Available frequencies may vary depending on country regulations and operating environment. Operating Range: 150 / up to 500 m (typical / optimal conditions) Audio Frequency Response: 40 Hz to 18 kHz (+/-3 dB) Dynamic Range: > 110 dB(A) System Distortion (at 1 kHz; +/- 38 kHz modulation): < 0.3% Maximum Output Level: + 20 dBu (XLR output) Image Rejection: > 110 dB typical Spurious Rejection: > 90 dB typical Overall Dimension (H x W x D): 44 x 483 x 366 mm Net Weight UR4S: 4.54 kg UR4D: 4.35 kg Power Consumptions UR4S: 9.6 – 13,2 W UR4D: 12 – 16 W