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680 ◆ Features Aspire Software Manual
The following limitations apply when you use long echo tail size (32msec or more) with the
enhanced Echo Canceller :
● Decreased VOIPU channels
If you choose a long echo tail size the number of available VOIPU channels is reduced to 3/4.
If you do not choose a long echo tail size, the number of available VOIPU channels is not
changed.
Example: Default VOIPU channels : 16ch -> Long echo tail size select : 12ch
● G.729/G.723.1 codec usage limitation
If you choose a long echo tail size, you should choose either G.729 or G.723.1.
* It is recommended to select G.729 for better voice quality.
NLP
If an echo problem is not resolved with the long echo tail size, NLP can be used to remove echo by
replacing low level voice to low level white noise (NLP noise).
By default, the adjustment of the NLP noise (white noise) level is automatically determined by Pro-
gram 84-17-04 (set to adaptive). If needed, the level between background noise and NLP noise can
be adjusted setting Program 84-17-04 to “fixed” and then adjust the NLP noise level using Program
84-17-05.
When sound continues from the remote side, as with Music on hold, the NLP can decrease voice
quality. In such cases, decrease the NLP Aggressiveness Control value in Program 84-17-06/07.
Please note if this is decreased, the echo level will be larger.
Programming
➻ 84-17-01 : VOIPU Echo Canceller Control Setup - Echo Canceller Mode
Enable (1) or disable (0) Echo Canceller mode.
➻ 84-17-02 : VOIPU Echo Canceller Control Setup - Echo Canceller Tail Size
Select the Echo Canceller Tail Size (1 = 8ms, 2 = 16ms). If 84-06-12 (Long Tail Echo Mode)
= on, this value is ignored – 84-06-14 is used instead. Only effective if 84-17-01 = enable.
➻ 84-17-03 : VOIPU Echo Canceller Control Setup - Echo Canceller NLP Mode
Enable (1) or disable (0) Echo Canceller NLP mode.
➻ 84-17-04 : VOIPU Echo Canceller Control Setup - Echo Canceller CNG CFG
Only effective if 84-17-03 = enabled. Select either Adaptive (0) or Fixed (1) for the NLP noise
adjustment. If set to Fixed, determine the level in Program 84-17-05.
➻ 84-17-05 : VOIPU Echo Canceller Control Setup - Echo Canceller NLP Noise
Adjust the NLP noise level (entries: 40 [-40dBm] - 70 [70dBm]). Only effective if 84-17-04 =
fixed.
➻ 84-17-06 : VOIPU Echo Canceller Control Setup - NLP Aggressiveness Control
Determines if value in 84-17-07 is + or -. Only effective if 84-17-03 = enabled (0 = +, 1 = -).
➻ 84-17-07 : VOIPU Echo Canceller Control Setup - NLP Aggressiveness Control Value
Setting of NLP strength. This entry is positive or negative based on the entry in 84-17-06. a
larger value provides a stronger NLP effect - a smaller value provides a weaker NLP effect.
(Entries: 0 - 32767)
➻ 84-17-08 : VOIPU Echo Canceller Control Setup - NLP Comfort Noise Configuration
Only effective if 84-17-03 = enabled. (Entries: 0 - 32767)
➻ 84-17-09 : VOIPU Echo Canceller Control Setup - Echo Canceller 4W Detect
(0=Disabled, 1=Enabled)
➻ 84-11-26 : Dterm IP CODEC Information Basic Setup - RX Gain
Adjust the receive gain as needed (0-28 [-14~+14]).