Introduction & Installation Page 1-7
HY02 Digital TBU User's Guide
This section of the handbook answers some of the
popular questions asked about the HY02
Digital
unit and
the way that it operates. If you have any questions
regarding the operation of the HY02
Digital
, please
contact your nearest distributor, or Sonifex directly.
Q : Why do I need a telephone balance unit ?
A : To convert a two wire telephone pair ( duplex ) to a four wire ( 2 simplex ) one input pair and one
output pair.
Q : What is a mix-minus signal and why do I need one ?
A : A mix-minus signal ( also called a clean-feed ) is an output from the mixing console which
includes signals from all of the audio channels except the channel that is allocated to the telephone
line. It is the signal that is used in the TBU send input, which is sent to the caller on the telephone line.
There are two reasons why the clean-feed signal is needed : Firstly, the TBU is designed to separate the
caller audio from the desk output audio, with an output consisting mostly of the caller audio. If the
caller audio is sent to the TBU send input, a feedback loop is created ( causing howling on the line )
and the hybrid can not separate the two signals. Secondly, the caller should hear what the other
listeners are hearing and not hear themselves.
Q : What are the main advantages between a conventional analogue hybrid and the
HY02 Digital ?
A : There are two : The main advantage is that the HY02
Digital
rejects signals equally across its
frequency band which results in a much better total rejection ratio. The second advantage is that the
HY02
Digital
can handle line echo and reflections of up to 28msec. This provides dramatic
improvements on rejection ratios over satellite links.
Q : Can I use open speakers with the HY02 Digital ?
A : Yes. Due to the echo cancellation, the HY02
Digital
can cope with a high level of acoustic
feedback without it becoming unstable.
Summary of Contents for HY02 DIGITAL
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