Wireless transmission systems, Squelch

Wireless transmission systems

With the ew 100 G2 series, Sennheiser puts an end to cable tangles and enab- les complete freedom of movement. The systems operate exclusively in the UHF band. UHF transmission is extremely reliable and is far less prone to interference than the overcrowded VHF band – harmonics from mains units, fluorescent tubes, refrigerators, computers, etc. are virtually eliminated. Also indoor propagation of UHF radio waves is better than VHF so that the RF power can be kept low – this is also an advantage when using multi-channel systems. Finally, UHF frequency ranges are being approved all over the world for radiomicrophone usage – in some countries licence-free.

There are three transmitter versions: The hand-held transmitter is a complete radiomicrophone in a single unit, the plug-on transmitter converts your favourite wired microphone into a radiomicrophone, the bodypack transmit- ter can accept a wide range of inputs including: omni-directional or cardioid clip-on microphones, head-worn microphone, guitar/instrument direct input and auxiliary units via the optional CL 2 line input cable.

Correct adjustment of transmitter sensitivity is vital. Too high and you get overmodulation and distortion, too low and you get undermodulation and a noisy signal. Please set the sensitivity correctly for the microphone/usage and check it before every performance to ensure best operation.

Sennheiser miniature clip-on microphones can be attached in various ways: they can, for example, be attached to the hairline or to clothing (e.g. tie or lapel). However it is fixed, please make sure that the microphone is protected against sweat/moisture and make-up.

Squelch

Pilot tone squelch

The transmitter adds a pilot tone to the audio signal. The receiver checks incoming audio signals to see if the pilot tone is present. In the absence of the signal, the receiver’s audio output will remain muted, even if a strong RF sig- nal is present.

This prevents strong interfering signals from causing hissing noise in the receiver when the transmitter is switched off.

In order to benefit from this feature, the pilot tone function must be activated on both the transmitter and the receiver. The pilot tone function is factory- preset to “ON” (= activated).

Field strength-dependent squelch

Depending on the strength of the received RF signal, the receiver’s audio out- put is opened or muted. Via the “SQELCH” menu of the receiver, the squelch threshold can be adjusted in three steps (LO, MID, HI).