Operation Manual

EF1210 C
OMMAND
S
ET
R
EFERENCE
ASPI Digital - The Sound of DSP Technical Support: 404.892.3200 59
AECS
N
-
SET SUPPRESSION MODE ON CHANNEL
N
TO NORMAL OR AGGRESSIVE
.
Suppression Level
Selection
The EF1210 has been designed and carefully optimized to provide the best possible
balance between removing as much vestigial echo as possible and maintaining natu-
ral, full-duplex performance when both parties speak at the same time or one party
tries to interrupt the other. As designed, the EF1210 should have no difficulty com-
pletely removing audible echo and adapting almost instantaneously to movements
and level changes within the room as long as the EF1210 is set up correctly. How-
ever, it is possible that some room environments may be so harsh as to strain the
boundaries of the operation of the EF1210. This may occur if the room is exceed-
ingly reverberant, the room acoustic gain limit is exceeded, or there is an excessive
amount of background room noise which results in a low signal-to-noise ratio on both
local speech and echo signals.
In conditions of excessive background noise, the signal-to-noise ratio of the local
speech signal can drop so low as make the conferencing system virtually unusable. In
such conditions, it is difficult for the AEC to cancel echoes much below the noise
floor. While the EF1210’s superior noise cancellation subsystem can reduce the
objectionable audible impact of high room noise to make the conferencing experience
more enjoyable and less fatiguing, in certain very harsh conditions this may mean that
the residual echo is now more audible because the noise floor has been so dramati-
cally reduced.
Another difficult situation for the EF1210 arises when the room acoustic gain limit is
approached or exceeded. As the acoustic gain limit is approached, it becomes more
difficult for the EF1210 to adapt to level changes or movement in the room (including
normal conferencing participant movement, movement of papers, etc.) as a result of
which snippets of echo may be heard for longer periods than would be desirable.
Should it be necessary to operate the EF1210 in such hostile conditions, the echo sup-
pression performance of the EF1210 may be enhanced to remove any vestigial traces
of echo, at the expense of doubletalk performance. In aggressive suppression mode,
users on the remote end will hear dropouts and clipping artifacts when they attempt to
talk across a local participant. The AECSn command may be used to select either
normal suppression mode (default) or aggressive suppression mode if required by
harsh room conditions.
The factory default setting for AECS
n
is 0 (normal).
Remote Commands
The following commands can be sent by the remote control device to set the suppres-
sion mode level.
Remote Command Effects
AECS
n x Set suppression mode on channel n to x.
x is the noise suppression mode (0 = normal; 1 =
aggressive).
AECS
n ? Request AECS status for channel n.