Technical information

Audio Interface
40 G30 - Module Hardware Description December 15, 2009
Table 2-16 gives the speech processing features.
Gain Control
The amplification (gain) level for each input and output device can be configured through AT
commands. Both basic and advanced audio modes provide AT commands to set the desired gain
levels for each audio path and audio sound type.
Table 2-17 gives the gain control features.
Audio Design
The audio quality delivered by G30 is highly affected by the application audio design,
particularly when using the analog audio interface. Therefore, special care must be taken when
designing the G30 audio interface. Improper design and implementation of the audio interface
will result in poor audio quality.
Poor audio quality is a result of electrical interferences, or noises, from circuits surrounding the
audio interface. There are several possible sources for the audio noise:
• Transients and losses on the power supply
• EMI from antenna radiations
• Digital logic switching noise
Table 2-16: Speech Processing Features
Feature AT Command
Default
Setting
Description
Basic Advanced
Echo Suppression
ATS96 AT+MAFEAT Disabled
Controls the echo and noise suppres-
sion.
Noise Suppression
Sidetone ATS94 AT+MAFEAT Enabled Controls the sidetone.
Table 2-17: Gain Control Features
Device Gain Command
Default
Gain
Description
Basic Advanced
Microphone
AT+MMICG AT+MMICG
8 Sets input speech gain level.
Headset Micro-
phone
8 Sets input speech gain level.
Mono Speaker AT+CLVL
AT+MAVOL
4 Sets voice and DTMF gain.
Differential Speaker AT+CRSL 4 Sets rings and alerts gain.