Silicon Laboratories SI2493/57/34/15/04 TAM Hands-Free Record OGM, ATU199&FFFD, AT+VRX Connect

AN93

7.6.2.1. Record OGM

The Si3000-to-RS232 gain register UC0 in the ISOmodem can be used to adjust the voice stream gain. Use the +VGR command to adjust the UC0 value in command mode. It is best to maintain two versions of +VGR: one for Si3000-to-RS232 and another for DAA-to-RS232.

	Table 127. TAM Hands-Free Record OGM
Host to Modem Commands /	Modem to Host Result	Local Modem Actions
Data	Codes/Data
AT+VGR=128	OK	Set the Si3000-to-RS232 receive gain (UC0) for TAM
		Hands-Free.
		Restore Si3000-to-DAA transmit gain path to allow
AT:U0B1,0500	OK	voice samples to reach FDV block for silence detection.
		This allows the driver to automatically end OGM
		recording.
AT+VSD=129	OK	Set sensitivity level for OGM recording silence detec-
		tion.
AT+VSM=4	OK	Select G.711U μ-law PCM, 8-bit, 64 kbps format. The
		voice driver will need to track the OGM format with the
		OGM PCM file.
AT+VTS=[1000,0,100]	OK	Play user record tone prompt.
AT:U1998	OK	Mute speaker to avoid echo (speakerphone algorithm
		off).
AT:U199&FFFD	OK	Enable microphone for OGM recording.
AT+VRX	CONNECT	Trigger receive operation. The first byte after the new-
		line character following the CONNECT message will be
		the first data stream byte.
		Receive OGM voice stream. During voice stream cap-
	[Voice Stream]	ture, the user can adjust the UC0 value via the
		<DLE><u> and <DLE><d> commands. The host voice
		driver will need track the number of adjustments and
		update the +VGR value for future use.
<DLE><!>	<DLE><ETX>	Terminate the receive operation. The modem will
		respond with <DLE><ETX> to mark the end of the data
	OK
		stream. The OK denotes the return to command mode.
AT:U0B1,0	OK	Disable Si3000-to-DAA transmit gain path. This
		ensures codec tones are not sent to the FDV and
		DTMF.
AT:U1992	OK	Mute the microphone.
AT:U199&FFF7	OK	Enable speaker for local ring tone/alert tones.

202 Rev. 1.3