Part One

Audio System Description

Overview

The audio unit acts as the processor for all audio functions. Select audio functions from the audio unit buttons or the audio remote switch (on the steering wheel). The center display provides the current audio status. The audio unit also supports playback function of compressed audio files (MP3/WMA) recorded on CD-R/RW.

The audio unit has a built-in EEPROM (electrically erasable programmable read-only memory). This memory holds the audio presets (AM/FM radio frequency, sound settings, etc.) even when the battery is disconnected.

A security signal is daisy-chained between the audio and vehicle components for integration into the vehicle's security system.

The speaker system is composed of the 40 mm tweeters, 17 cm front/rear door speakers, and 20 cm subwoofer. For some models, a 8 cm center speaker and satellite speakers are added into the dashboard center section and the rear quarter pillar section. The subwoofer is mounted in an enclosure for improving bass management.

Active Noise Cancellation (ANC) System

The audio system includes an active noise cancellation (ANC) system to cancel some of the vehicle noise. The audio unit receives the engine speed pulse (NEP) from the PCM and outputs a sine-wave-sound through the audio speakers to cancel low-frequency noise from the engine. The ANC system also uses two microphones to detect and monitor low frequency noise in the passenger compartment. The microphones feed information back to the audio unit which adjusts the speaker output to reduce the noise. The ANC also receives input from the door open/close (INTR LT) signal from the MICU via the B-CAN. Anytime a door is opened, the ANC system temporarily stops working.

Speed-sensitive Volume Compensation (SVC)

The audio systems are equipped with speed-sensitive volume compensation (SVC). The audio unit receives the vehicle speed pulse (VSP) from the PCM. The system processes the speed input and increases the audio system volume level as the vehicle speed increases to compensate for the various interior noises that occur at higher speeds. When the vehicle slows down, the volume returns to its normal level. The SVC has four settings: SVC OFF, LOW, MID and HIGH that can be adjusted using the audio unit. The SVC comes from the factory with MID set as the default (see the owner's manual for more information).

USB Adapter

The audio unit can play digital music from portable audio players, USB drive, etc. when the device is plugged into the USB adapter. The audio unit uses the GA-Net to allow you to control the device from the audio unit when searching and playing the files.

NOTE: Not all players and player functions work with the USB adapter. Please see the owner's manual for more information.

Telematics Muting Logic

The navigation system allows voice control for the audio system and XM radio. The navigation system uses the GA-Net bus to communicate the voice control commands to the audio unit. When using the navigation TALK/BACK button, the audio is muted on all speakers and you hear navigation sound on the center speaker. When using the navigation or route guidance (RG), the front speakers provides the navigation sound while the rear speakers continue to play the audio. For more information, see the navigation and HFL sections.

The outline of the muting logic is shown in this table.