Technics MT5634SMI-92 manual Voice Commands, SocketModem Global MT5634SMI Developer’s Guide

Chapter 6 – Voice Commands

<cml> is used by the PC to select a compression method. The valid range of values is from 128– 256. The range of values from 0–127 is reserved for future standards.

<vsr> is used to select the modem voice sampling rate from the set of those supported. The unit of measure is samples per second. See the +VSM=? command for the list of sampling rates supported by the modem.

<scs> has different meanings in voice transmit and voice receive modes. In receive, the PC uses <scs> to select greater amounts of compression activity; larger <scs> values mean that the PC wants the modem to treat noisier conditions as silence. There is no unit of measure for this parameter; it merely represents a number in a range. 0 disables modem silence compression.

In voice transmit mode, the PC signals the modem that the data stream was recorded with silence compression by selecting a non-zero value from within the valid range (the same value as receive). Unpredictable results can occur if you 1) enable silence compression for transmitting a voice data stream that was not recorded with silence compression enabled, or 2) you disable silence compression for transmitting a voice data stream that was recorded with silence compression enabled. You can modify the silence expansion with the <sel> parameter. The range of valid values is 0–255. The modem may limit silence compression sensitivity to a narrower range (e.g., 120–128). A setting of <scs>=0 disables silence compression.

<sel> is used to modify the amount of silence expansion. This parameter represents the minimum amount of silence that the modem will expand a period of silence that was previously deleted with a non-zero <sel> parameter. A setting of <sel>=0 means the modem will not modify the silence expansion. The valid range of values is ____ - ____ in 0.1second increments. The modem ignores

the <sel> parameter if the <scs> parameter is 0 (silence compression disabled).

Command:	+VSM=?	Report Voice Compression Method
Result Codes:	OK
Description:	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.
	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),(127-129),(0-50)
	132,"ADPCM/AQ",2,40,(7200),(128),(0-50)
	The compression method identifiers for PCM coding display the general classification of the
	compression method in the form <cmid>.
	Non-PCM coding reports the compression method identifiers in the form <cmid>/<author>, where
	<cmid> is the general classification of the compression method and <author> is the source of the
	method. The source <author> may be a proprietary method or it may reference a published
	standard. Each field limit is 20 characters. The +VXT command starts a translation to or from a
	particular manufacturer's proprietary voice data stream format to an unsigned (non-PCM) format.
	Identifier	Description
	Signed PCM	Linear PCM sampling using twos complement signed numbers
	Unsigned PCM	Linear PCM sampling using unsigned numbers
	A-Log/Author	Compression using a-law
	U-Log/Author	Compression using u-law
	DPCM/Author	Differential Pulse Coded Modulation
	DPCMAQ/Author	Differential Pulse Coded Modulation with Adaptive Quantizier
	ADPCM/Author	Adaptive Differential Pulse Coded Modulation
	VSELP/Author	Vector Sum Exited Linear Predictor
	RELP/Author	Residual Exited Linear Predictor
	CELP/Author	Code Book Exited Linear Predictor
	CVSD/Author	Continuously Variable Slope Delta Modulation
	TDHS/Author	Time Domain Harmonic Distortion
	ADM/Author	Adaptive Delta Modulation
	DM/Author	Delta Modulation
	APC/Author	Adaptive Predictive Coding
	ATC/Author	Adaptive Transform Coding
	SBC/Author	Sub-Band Coding
	GSM/Author	Regular Pulse Exitation Long-term Predictor (RPELTP)
	LPC/Author	Linear Predictive Coding
	EAPDPCM/Author	Embedded Bit ADPCM

SocketModem Global MT5634SMI Developer’s Guide 54