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Chapter 4 – Voice Commands
+VSD
Silence Detection Sensitivity
Description:
Sets the silence detection sensitivity and the required period of silence before the
modem reports silence detected at the end of a voice receive, either with the
Presumed End of Message (Quiet) or Presumed Hang Up (Silence) event reports.
The table below outlines the possible combinations of the +VSD and +VSM
commands using the <sds> parameter. An <sdi> parameter value of 0 means that
long-term silence detection is disabled. (Note that long-term silence detection refers
to the use of this function to detect the end of a voice receive (i.e., the user stops
talking).
The parameter <sds> is used by the PC to select greater amounts of modem silence
detection activity; larger values imply that the PC wants the modem to treat noisier
conditions as silence. The value entered for <sds> has no actual unit of measure.
The modem may limit silence detection sensitivity to a more narrow range (e.g., from
120 to 136). A setting of 0 has no meaning.
The parameter <sdi> sets the required period of silence before the modem can report
silence detected either with the Presumed End of Message (Quiet) or Presumed
Hang Up (Silence) event reports. A value of 0 disables modem silence detection, in
which case the modem will not report the Presumed End of Message (Quiet) or
Presumed Hang Up (Silence) event reports.
AT+VSD=<sds>,<sdi>
<sds> A decimal number corresponding to the selected parameter:
0
Use +VSM silence compression setting and algorithm for long-term
silence detection if +VSM is in use
OR
Use default long-term setting silence detection level and algorithm if
+VSM is not in use.
127 Sets less aggressive long-term silence detection independent of
presence or use of silence compression.
128 Sets nominal long-term silence detection independent of presence or
use of silence compression.
129 Sets more aggressive long-term detection independent of presence or
use of silence compression.
<sdi> A decimal number specifying the required period of silence in units of 0.1
seconds, before the modem can report silence detected at the end of a
voice receive either with the Presumed End of Message (QUIT) or
Presumed Hang up (SILENCE) event reports. A value of 0 disables the
modem silence detection. The range is 0.1 to 25.5 seconds for <sdi>=1
to 255.
OK if values are valid.
ERROR if one or more of the following apply: 1) the <sds> or <sdi> parameter
entered is out of range, or 2) either of the two parameters is missing from the
command string. If an error occurs, modem retains the previous <sds> and <sdi>
parameter values.
+VSD?
Displays current or selected values.
+VSD=?
Displays a list of the supported values.
Syntax:
Values:
Result Codes:
Reports:
Multi-Tech Systems, Inc. AT Commands for the MultiModem & SocketModem MT9234 Series (S000434H)
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