Extron electronics XMP 240 C AT, Руководство пользователя, Страница: 33 / 139

XMP 240 C AT • DSP Configurator Software 27
4
Set Defaults Button — Resets all filter parameters of all filters in the filter list to their
default values.
To reset a single filter to default parameters, right-click the filter number on the left side
of the
Filter
dialog box, and select
Set to Default
(see figure 42).
Figure 42. Set Single Filter Parameters to Default
5
OK Button — Confirms changes made to the contained parameters and closes the
Filter
dialog box.
6
Cancel Button — Reverts any changes made to the contained parameters back to
their states when the current instance of the
Filter
dialog box was opened and closes
the dialog box.
7
Filters Help Button
— Opens the About Filters topic in the DSP Configurator Help
file. This help file topic discusses each filter type in greater detail.
Input AEC Block
About AEC
Echo occurs when audio from a talker in the far end is received and amplified into the near
end listener’s room, with that sound then being picked up by microphones in the near end
acoustic space and sent back to the far end. The amount of signal sent back to the far end
talker can be substantial, and with the added transmission delay, the result is an echo effect
that can seriously compromise communication in a teleconference or videoconference.
The Extron Acoustic Echo Cancellation (AEC) processor removes the potential echo
signal at the near end mic channel by comparing it to the received signal from the far end,
designated as the “reference,” and then creating an adaptive filter to cancel the potential
echo before it is sent back to the far end.
Successful operation of the AEC processing block is mainly a function of proper gain
structure and selection of an AEC reference. This section provides an overview of those two
elements.
Proper gain structure involves the relationship between the signal at the selected reference
and the signal at the mic input, within the context of proper levels for the reference and mic
inputs independently. The mic input gain setting will naturally be optimized for the voice level
of the talker in that room. Therefore, the amount of signal from the far end picked up by the
mic is dependent on how much far end signal is being amplified in the near end room and
the distance from the mic to the speakers.