Modem User Manual

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There five factory-set audio profiles as follows:
• Portable hands free
Low-level is recommended.
• Handset
Low-level is recommended.
• Car kit
Low-level is recommended.
• Speakerphone
High-level is recommended.
• Headset
Low-level or High-level can be used with headset, depending on requirements.
Portable hands free is the factory-set default profile. The modification, configuration,
manipulation and storage of audio profiles is achieved with the AT*E2EAMS (Audio
Profile Modification) and AT*E2APR (Audio Profile).
5.9.1 Auxiliary Audio to Mobile Station (AUXI)
AUXI is a single-ended auxiliary analogue audio input to the wireless modem.
Internally, the signal is routed to the CODEC (COder/DECoder), where it is converted
to digital audio and mapped to an internal bus.
AUXI provides a DC bias when it is used as the microphone input in Portable Hands-
free applications. All other sources must be AC-coupled to avoid attenuation of low
frequencies, and to prevent incorrect biasing or damage to the AUXI input. Use a
capacitor greater than the value shown in the table below.
The AUXI input is a passive network followed by the transmit part of the CODEC.
Parameter Conditions Min Typ Max Unit
max input gain 142 158 178 mVrms
Input voltage full scale
min input gain 447 501 564 mVrms
Frequency response -3dB cut-off 300 3400 Hz
Output dc bias level 2.16 2.4 2.64 V
AC coupling capacitance 1
µF