Specifications

Rev. 8 May.12 Proprietary and Confidential 127

7: Voice Commands

Introduction

Note: This chapter applies to modems supporting analog and PCM digital

audio interfaces. For modems supporting I2S audio, see I2S Audio

Commands on page 163.

Voice-enabled Sierra Wireless Mini Card modems (for example,

MC8795V) have built-in audio support that allows the modems to be

used as mobile phones.

Note: Voice-enabled SL808x modems support the general audio function-

ality described in this chapter. Specific details are to be determined.

The modems all support a single analog audio interface that can be

used for handset-style applications or headset applications, and a

PCM digital audio interface. The modems have a wide range of

software-controlled audio filtering and amplification 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 (depending on module

type):

• Adjustable gain up to +40 dB

• Several adjustable filtering stages (high-pass and slope filters)

• Noise cancellation

• Configurable echo cancellation for various acoustic environ-

ments. (For example, 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