US Robotics 56K USB Modem User Manual page 91

+VSD=<sds>,<sdi>—Silence Detection (QUIET and SILENCE)
Use this command to set the silence detection sensitivity (<sds>) and silence detection interval (<sdi>).
The <sds> parameter defines the line noise sensitivity level in decibels.
The <sdi> parameter specifies the amount of time the modem waits before reporting silence to the DTE. It
is used for determining the presumed hang-up (SILENCE), after which the modem sends <DLE>-s to the
DTE. The default is 50 (5 seconds).
Result codes:
• OK if <sds> = 0—255 and <sdi> = 0—255.
ERROR if <sds> ≠ 0—255 or <sdi> ¼ 0—255.
•
Larger values of <sds> indicate that the modem is to treat noisier line conditions as silence (see Table
193).
Table 193. <sds> Values
Value
<sds> = 128 Nominal level of sensitivity; –40 dBm (default).
<sds> > 128 More aggressive; <sds> = 129 is –39 dBm.
<sds> < 128 Less aggressive; <sds> = 127 is –41 dBm.
Table 194. +VSD Extended Syntax Commands
Value
+VSD=<sds>,<sdi>
+VSD?
+VSD=?
+VSM=<cml>,<vsr>—Compression Method and Sampling Rate Specifications
Use the +VSM* command to set the voice compression method and the sampling specification. The <cml>
parameter identifies the compression method and the <vsr> parameter identifies the sampling rate.
Result codes:
• OK if <cml> = 128—133 and <vsr> = 7200, 8000, 11025.
ERROR if <cml> ≠ 128—133 or <vsr> ≠ 7200, 8000, 11025.
•
Table 195. Compression Method
<cml>
128
129
130
131
132
133
Table 196. +VSM Extended Syntax Commands
Command
+VSM=<cml>,<vsr>
Sets the silence sensitivity level and the silence detection interval.
Displays the current silence detection sensitivity and silence detection interval.
Displays the range of supported values for the silence detection sensitivity and
silence detection interval.
Compression Method
8-bit linear.
16 bit linear (default).
8-bit A-law.
8-bit μ-law.
IMA ADPCM.
G.729.
Sets the compression method and the sampling rate.
Function
Function
Available Sampling Rates
7200, 8000, 11025
7200, 8000 (default), 11025
8000
8000
8000
8000
Function
56K USB Modem
User Guide
Command Reference - 85