Silicon Laboratories SI2493/57/34/15/04 - Manual (Page 202)

A N 9 3
202 Rev. 1.3
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 /
Data
Modem to Host Result
Codes/Data
Local Modem Actions
AT+VGR=128 OK
Set the Si3000-to-RS232 receive gain (UC0) for TAM
Hands-Free.
AT:U0B1,0500 OK
Restore Si3000-to-DAA transmit gain path to allow
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
-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:U199|8 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.
[Voice Stream]
Receive OGM voice stream. During voice stream cap-
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>
OK
Terminate the receive operation. The modem will
respond with <DLE><ETX> to mark the end of the data
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:U199|2 OK Mute the microphone.
AT:U199&FFF7 OK Enable speaker for local ring tone/alert tones.