Intel 537EX manual Intel Confidential, IS-101Voice Mode AT Commands, m= <cml>, <vsr>, <scs>, <sel>

IS-101 Voice Mode AT Commands

Table 25. Voice Mode Command Descriptions (Continued)

Command Default Description

Compression Method Selection: This command contains four parameters that specify the voice compression method, voice sampling rate, silence compression sensitivity, and the degree of silence expansion. The DCE can support different capabilities for each compression method.

m= <cml>, <vsr>, <scs>, <sel>

Defaults: m = 140, 8000, 0, 0

<cml> Compression Method: This parameter selects a voice compression method. The DTE can obtain the label and a string constant identifier by using the +VSM? command.

Range: 0–2, 128, 129, 132, 140, 141

0LIN1: 8-bit Linear PCM (pulse code modulation) sampling using twos-complement signed numbers

1LIN2: 16-bit Linear PCM sampling using unsigned numbers

2AD4: 4-bit Adaptive differential pulse code modulation

128LIN1: 8-bit Linear PCM (pulse code modulation) sampling using twos-complement signed numbers

129LIN2: 16-bit Linear PCM sampling using unsigned numbers

		132	AD4: 4-bit Adaptive differential pulse code modulation
		140*	CL1: 8-bit Intel A-law
	manufac-	141	AD3: 3-bit Adaptive differential pulse code modulation
		<vsr> Sampling Rate: This parameter selects the DCE voice sampling/digitizing rate for the voice
+VSM=m	turer-
		signal. The supported sampling rates are dependent on the compression schemes used. Use the
	specified
		+VSM=? command to obtain supported sampling rates.
		Range: 4800, 7200, 8000, and 11025 samples/second
		4800	Default used by previous Intel modems
		7200
		8000*	Used by some bulletin boards
		9600
		11025	Used by many Windows* WAV files

<scs> Silence Sensitivity: The function of this parameter depends on whether the DTE is transmitting or receiving in voice mode. The DTE can modify the silence expansion using the <sel> parameter. When transmitting voice, a non-zero value of this parameter informs the DCE that the data stream was recorded with silence compression.

Transmission: Range: 0

0*Disabled

When receiving voice, this parameter changes the level of noise that the DCE treats as silence. A higher ‘n’ number raises the threshold of noise detection.

Reception: Range: 0
0*	Disables DCE silence compression
increments of 1	Raises noise detection threshold

NOTE: An asterisk (*) denotes the factory-default setting.

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