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

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Silicon Laboratories SI2493/57/34/15/04, SI2494/39 manual TAM Hands-Free Record OGM, ATU199&FFFD, AT+VRX Connect, Dleetx