Voice Commands; Introduction; Command Summary - Sierra Wireless MC8775 Reference Manual

7: Voice Commands

•

Introduction

• Audio profiles
•

Command summary

• Command reference
Rev 2.9 Oct.08

Introduction

The MC8775V, MC8785V, MC8790V, MC8791V, and MC8792V
modems have built‐in audio support that allow the modems to
be used as mobile phones.
The modems all support a single analog audio interface that
can be used for handset‐style applications or headset applica‐
tions, and a PCM digital audio interface.The modems have a
wide range of software‐controlled, audio filtering and amplifi‐
cation stages, which minimize the amount of external circuitry
required on the host system.
At its most basic configuration, the host audio system could
contain:
• A microphone / speaker combination (handset)
—or—
• A headset jack
The audio pass band for the primary and secondary audio
paths extends from 300 Hz to 3.4 kHz in both the receive and
transmit directions.
These transmit audio features are supported:
• Adjustable gain up to +40 dB
• Several adjustable filtering stages (high‐pass and slope
filters)
• Noise cancellation
• Configurable echo cancellation for various acoustic
environments like headset, handset, and speakerphone
• Adjustable sidetone from mute to unity gain
These receive audio features are supported:
• Adjustable gain up to +24 dB
• High‐pass filter stage
• Output driver stages, which can drive speakers directly
The module also provides 13‐tap FIR (Finite Impulse
Response) filtering for both the receive and transmit paths to
equalize the acoustic response of the speaker and microphone.
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