Vsm Select Voice Compression Method - Multitech MultiModem SocketModem MT9234 Series At Commands Reference Manual

+VSM
Description:
Syntax:
Values:
Response:
Result Codes:
Reports:
Multi-Tech Systems, Inc. AT Commands for the MultiModem & SocketModem MT9234 Series (S000434H)
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Select Voice Compression Method
Sets the modem to a specified voice compression method, silence compression
sensitivity, and voice sampling rate. The modem can maintain a different event
detection capability for each compression method. For example, you may want to
record your welcome message with the lowest amount of silence removal, with the
goal of reducing distortion. For other messages you may want a more assertive
silence removal, to limit disk space used for recording purposes.
AT+VSM=<cml>,<vsr>
<cml> A decimal number identifying the compression method. The valid values are
128, 129, 130, 131, 132. Default is 129.
<vsr> A <range of values> containing the supported range of for voice samples per
second of the analog signal (8000).
Response to AT+VSM=?
128,"8-BIT LINEAR",(7200,8000,11025)
129,"16-BIT LINEAR",(7200,8000,11025)
130,"8-BIT ALAW",(8000)
131,"8-BIT ULAW",(8000)
132,"IMA ADPCM",(7200,8000,11025)
OK if the modem accepts the command.
ERROR if one or more of the following apply: 1) the any parameter entered is out of
range, or 2) any of the four parameters are missing from the command string. If an
error occurs, the modem retains the previous <sds> and <sdi> parameter values.
+VSM? Displays current or selected values.
Reports <cml>,<vsr>
Example: 1,8000,0,0.
The default is 129,"16-BIT LINEAR",8000
+VSM=? The +VSM=? command reports several compression method identifiers
in one of two ways: either 1) a compression method (for PCM coding)
from the table below, or 2) a co-operative identifier (non-PCM coding)
used with other manufacturer's equipment.
Reports the following:
<cml> See above
<cmid> An alphanumeric string describing the compression method
(UNSIGNED PCM, IMA ADPCM, 2-Bit ADPCM, or 4-Bit
ADPCM)
<bps> A decimal number defining the average number of bits in the
compressed sample not including silence compression (2, 4,
or 8)
<tm> A decimal number (0) reporting the time interval in units of
0.1 seconds between timing marks. 0 reports timing marks
are not supported.
<vsr> See above. A report of 0 indicates not supported.
Example: The following shows an inquiry about the modem support
of compression and other data. In this example, the modem
reports that it supports two compression methods.
AT+VSM=?
128,"SIGNED PCM",12,0,(7200-8000,11025)
132,"ADPCM/AQ",2,40,(7200)
Chapter 4 – Voice Commands
52