
98 VoIP
dimPrintECC
Syntax:
dimPrintECC chNum, Filter
Prints a DSP channel echo canceller filter coefficients for the foreground
or background filters. The filter coefficients are set by the ECAN algorithm
to cancel the echo received from the TDM network. Each milliseconds of
the ECAN has 8 coefficients (taps), so a 32 milliseconds ECAN tail, for
example, has a total of 256 coefficients that you must print to see the full
state of the ECAN. The printed data is usually only meaningful to an ECAN
DSP engineer; it is typically collected for them. The coefficients are not
cleared when the Open Loop detection removes the ECAN from the path;
the last values present remain.
This command freezes the ECAN coefficients, requests the correct
number of coefficients based on the ECAN tail length (from 256 to 1024
coefficients) and then unfreezes the ECAN. Because a 128 milliseconds
ECAN tail length prints 1024 coefficients, 8 coefficients print for each line.
The following table describes the command parameters.
Table 15
Command parameters
Parameter Value Description
chNum
0–31
Channel number of the call on the VGMC
filter
–
0 = foreground filter (default)
1 = background filter (if present)
The following example shows command output.
-> dimPrintECC 0
TCID 0: Echo Canceller coefficients (data length = 56)
00000000
00000000
00000000
00000000
00000000
00000000
00000000
.
.
.
[eight coefficients printed per msec of ECAN tail length]
.
.
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Nortel Communication Server 1000
Troubleshooting Guide for Distributors
NN43001-730 02.02 31 December 2009
Copyright © 2008-2009 Nortel Networks. All Rights Reserved.
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