Sennheiser EW 300 G2 - Manual (Page 83)

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Additional information
HDX noise reduction
Progress you can hear:
The evolution wireless G2 series is equipped with HDX , the Sennheiser noise
reduction system that reduces RF interference. It increases the signal-to-
noise ratio in wireless audio transmission to more than 110 dB.
HDX is a wideband compander system which compresses the audio signal in
the transmitter in a 2:1 ratio (related to dB) to lift it above the inherent noise
floor of the RF link. A 110 dB dynamic range signal is thus transmitted with
an effective dynamic range of only 55 dB, which is above the 60 dB noise floor
of the RF link. In the receiver the signal is expanded in an identical and
opposite way in a 1:2 ratio to restore the original signal, at the same time
reducing the RF noise to below the noise floor of the receiver.
HDX has been specially developed for high quality radiomicrophone systems.
Note:
Only transmitters and receivers that are equipped with HDX can work
correctly with each other. If non HDX equipment was mixed with HDX , the
dynamic range would be drastically reduced and the transmission would
sound blunt and flat.
HDX is permanently active and cannot be switched off.
Wireless transmission systems
With the ew 300 G2 series, Sennheiser puts an end to cable tangles and
enables 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 two transmitter versions: The hand-held transmitter is a complete
radiomicrophone in a single unit, the bodypack transmitter 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
RF link
Transmitter
Inherent noise
of the RF link
Receiver