Sennheiser EM 3731-II Stereo Receiver User Manual


 
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Additional information
Additional information
HiDyn plus™ (HDP) or HDX noise reduction
This product family is equipped with the Sennheiser noise reduction
systems HDP and HDX. Both compander systems operate on the same
principle (described in the following for HDP) but use different parameters
(e.g. time constant, type of control). HDP reduces RF interference. It
increases the signal-to-noise ratio in wireless audio transmission to more
than 110 dB. HDP 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. 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.
HDP has been specially developed for high quality radio microphone
systems.
All receivers of the product family feature a AES3 digital audio output for
digital mixing consoles. In the receiver the audio signal is digitalized as
early as possible so that the noise reduction (compander) can be realized
digitally.
Squelch
Depending on the strength of the received RF signal, the receiver’s audio
output is opened or muted. Via the “Squelch” menu, the squelch threshold
can be adjusted in 13 steps from 0 to 30 μV.
RF link
Transmitter
Receiver
Inherent
noise
of the RF link
Only transmitters and receivers that are equipped with the same
compander system can work correctly with each other. If this is not
the case, the dynamic range will be drastically reduced and the
transmission will sound blunt and flat.