Radio, Stereo, and Compact Disc: Description and Operation

RADIO/AUDIO SYSTEM DESCRIPTION AND OPERATION

The Entertainment System on this vehicle is configured with either a base or an uplevel system. Both the base and uplevel systems contain a radio, antenna, speakers, and on some vehicles an optional audio amplifier and remote CD changer. Radio data system (RDS) is standard on all radios.
The following list shows the radios available for this vehicle:
- Base Radio (U1P) - AM/FM Stereo, CD with Programmable Equalizer, and RDS
- Uplevel Radio (U1Q) - AM/FM Stereo, Cassette, CD with Programmable Equalizer, and RDS

Radio Features:

RADIO FEATURES

Cassette Features:

CASSETTE FEATURES

Compact Disc Features:

COMPACT DISC FEATURES

Each item in the list below represents topics covered in detail below.
- AM/FM Reception
- Antenna
- Theft Deterrent
- Remote Playback Device
- Radio Data System (RDS)
- Steering Wheel Controls
- Tape/CD Player Error Messages
- XM Satellite Radio

AM/FM Reception

Radio Signal
The radio signal is sent from a broadcast station and is then received by an antenna. The strength of the signal received depends on the following:
- The power output (wattage) of the broadcasting station
- The location of the vehicle (or receiver) relative to the broadcast tower.
- Obstacles between the tower and the receiver
- Atmospheric conditions
- What band (AM or FM) the station is broadcasting
- Type of antenna and the ground plane

AM Reception
The AM band has a lower frequency range than the FM band. These longer wavelengths:
- Bend around obstacles
- Follow the curvature of the earth
- May reflect off the ionosphere (skip)
The AM frequencies have longer range due to the ground wave. The ground wave follows the curvature of the earth and is effected by its conductivity. Greater conductivity equates to less signal loss thus transmission over water is better than over land. The AM band has a range of 80-320 km (50- 200 miles).

FM Reception
The shorter wavelengths of the higher frequency FM band:
- Reflect off obstacles
- Are absorbed by the ground
- Penetrate the ionosphere
Broadcasts in the FM band are limited to "line of sight" reception which is typically 40km (25 miles). Even when out of a direct line of sight, the signal may be reflected into areas that would be in a "shadow" otherwise. Factors which affect the line of sight include:
- Height of the broadcast antenna
- Height of the receiving antenna
- Terrain and buildings in the broadcast path

XM Satellite Radio
XM satellite radio provides digital radio reception. The XM signal is broadcast from two satellites and, where necessary, terrestrial repeaters. The high power satellites allow the antenna to receive the XM signal even when foliage and other partial obstructions block the antennas view of the satellite. Terrestrial repeaters are used in dense urban areas. These repeaters will receive the satellite signal and re-broadcast them at much higher power levels in order to ensure reception in areas with densely packed tall buildings.

Diversity Antenna System
The diversity antenna system uses both front and back windows with an integral antenna built between the glass layers of the windshield and as an applique to the rear glass. Any damage to the antenna requires replacing the glass.
A diversity antenna system is designed to deliver the best radio signal reception possible. Two antennas are used to form a diversity system. The primary antenna is part of the rear window and looks similar to the defogger grid. This antenna receives both AM an FM signals. The secondary antenna is part of the front windshield and receives only FM signals. The antenna reception signals are sorted out by the radio antenna module. The radio antenna module is enabled when the radio is turned on. When the AM or FM band is selected on the radio, the antenna module connects the rear window antenna directly to the radio. In addition, when the FM band is selected an enable signal is sent to the antenna module. Superimposed on this enable signal is the strength of the signal being received by the radio tuner. The antenna module now performs two functions. It switches between the front and rear antennas, monitoring the radio signal strength and combines both signals and phase aligns them to create one strong signal.

Theft Deterrent
The "Theftlock" theft deterrent system is a feature on all base and uplevel radios. There is no need to program a security code into the radio as in past model years. The theft deterrent system now utilizes class 2 serial data to determine if the radio is in the appropriate vehicle. Each time the radio receives the "run" power mode message, it compares the VIN information it has stored to the VIN information received from a module on the class 2 serial data circuit responsible for transmitting that information. If a mis-match occurs, the radio display will indicate to the user the radio is locked. Once this takes place, a DTC will set, the radio will not respond to any button presses and become inoperative. The two scenarios able to cause this condition are:
1. A radio is installed from another vehicle.
2. A module which communicates on the class 2 serial data circuit which supplies VIN information to the radio is replaced and not properly setup with the correct VIN information for that vehicle. The only way to unlock the radio is by using a scan tool. Always refer to the table to diagnose the "Theftlock" DTC for further information.

Remote Playback Device
The remote playback device is 12 disc remote CD changer. The radio controls and communicates with the remote playback device through Class 2 communication.
The remote CD changer allows for up to 12 compact discs to be played continuously. Normal size discs may be played using the trays supplied in the magazine. The magazine must first be loaded with discs before it can played. Press the button on the back of the magazine and pull gently on one of the trays. Load the trays from top to bottom, placing a disc on the tray label side up. If a disc is loaded label side down, the disc will not play and an error will occur. Gently push the tray back into the magazine. Repeat this procedure for loading up to 12 discs in the magazine. Once the discs are loaded into the magazine, slide open the door of the compact disc changer. Push the magazine into the changer in the direction of the arrow marked on the magazine.
Close the door by sliding it all the way to the right. If the door is left partially open, the changer will not operate. When the door is closed, the changer will begin checking for discs in the magazine. This will continue for up to two minutes, depending on the number of discs loaded. To eject the magazine from the player, slide the CD changer door all the way open. The magazine will automatically eject. Whenever a CD magazine with discs is loaded in the changer, the CD changer symbol will appear on the radio display. If the CD changer is checking the magazine for CD's, the CD symbol will flash on the display until the changer is ready to play.

Radio Data System (RDS)
All audio systems are equipped with technology known as the Radio Data System (RDS). RDS is a system that sends data along with the audio of the FM station you are currently tuned to. RDS is a standard that defines how a FM broadcast station may send digital data along with the audio program. Think of it as a one way wireless modem, allowing the broadcaster to send information about his program to your receiver.

RDS data is carried in what is known as a "subcarrier". A subcarrier is a frequency that the FM broadcaster is authorized to use to send data or other audio programs that are not audible in the main audio program. RDS information can be used to display program information and to control the radio.

To receive the RDS signal, all that is needed is an FM receiver with a RDS circuit. A special integrated circuit capable of dealing with the RDS signal is in the RDS circuit and passes it along to the receiver's microprocessor where it is decoded and acted upon.

RDS Basic Information
RDS basic information:
- RDS functions are provided in the FM broadcast band only.
- RDS functions will only work with FM broadcast stations that are broadcasting RDS data.
- Not all FM Broadcast stations broadcast RDS data or offer all of the RDS services.
- RDS functions may not work properly when reception is weak, reception is of poor quality, or RDS is not implemented properly by the FM Broadcaster.
In some cases, a radio station broadcasting incorrect information may cause the RDS features of the radio to appear to work improperly. Broadcast RDS information can be used in a variety of ways by the receiver and listener, but basically falls into two categories: Display and Control.

Displaying Program Information
RDS displays textual information such as:
- The name of the station.
- The type of program.
- General information such as artist and song title, call in phone numbers, etc.
RDS is always on. When tuned to a non-RDS station, your radio will display frequency information as you would normally expect. When tuned to a RDS station, your radio will change from displaying the frequency of the FM station to displaying the call letters of the station or display the nickname of the station. This feature is known as the Program Service Name.

Controlling The Radio
RDS can control the radio when data the receiver can use responds to timely information and performs the following:
- Interrupt the playback of your cassette or CD for traffic or emergency bulletins.
- Search for stations by type of program.
- Automatically follow networked programming from transmitter to transmitter as you travel from one listening area to another.
- Set your clock to the time that the RDS broadcast station broadcasts.

Viewing And Selecting RDS Program Type Information
The Program Type feature is activated by pressing the program type button (labeled PROG TYPE). The program type name will be displayed (if the broadcaster is broadcasting one). The program type name is an eight-character name that the broadcaster may use to further identify the type of programming currently being broadcast. Turn the SELECT knob to select the desired program type. Press the SEEK SCAN arrows to find radio stations of the selected program type. If both program type and traffic are on the radio will search for stations with traffic announcements and the selected program type. If a station with the selected program type is not found, the radio displays "NOT FOUND".

Using The RDS Traffic Feature
Some RDS broadcasters may carry traffic information programming to inform you of current traffic conditions in your listening area and is indicated by the icon in the radio display. RDS enables the broadcaster to get this information to you even when you are listening to a tape or compact disc. This feature can be enabled or disabled by the listener. Press the TRAF button to find a station that claims to carry traffic information. You may do this even when playing a cassette tape or compact disc. This action will operate in the background without interrupting the current playback. If the radio is not currently tuned to an RDS traffic station, the radio will immediately SEEK an RDS traffic station. If the radio finds an RDS traffic station, the TRAF icon will appear in the radio display as will brackets around the [TRAF] icon. If the radio cannot find an RDS traffic station after searching through the entire FM band, the radio will display "NO TRAFFIC". When a traffic announcement comes on the tuned radio station, you will hear it, even if the volume is muted or a cassette or CD is playing.

Viewing Messages
When INFO appears on the radio display, a new message is available for viewing. These messages are from the RDS broadcaster and may be general information such as artist and song title. To view the text message, press the INFO button. If the whole message does not appear on the display, parts of the message will appear every three seconds until the message is completed. To view the message faster, press the INFO button again.

Alternate Frequency (AF) Switching
RDS permits broadcaster's to send information to the radio that allows the radio to automatically switch frequency to the best quality station in that broadcaster's network. Since the radio is displaying the broadcaster call letters or nickname, the listener will not see the frequency during an AF switch unless you have changed the default display to be frequency instead of Program Service name.
To enable or disable AF switching, perform the following:
- Press and hold the BAND button for two seconds or more.
- The radio will display "AF ON" or "AF OFF".
When AF is enabled and you recall a RDS station stored on preset, the radio determines if the station stored is of acceptable quality. If not, the radio checks all available AF's for your station. If the radio fails to locate your program, "AF SEARCH" will be displayed as the radio scans across the band looking for your program or an affiliated network. If the radio cannot find the original station or an acceptable alternate frequency "NOT FOUND" will be displayed and the radio returns to the original frequency for the preset.

RDS Clock Time
Broadcasters can choose to send clock time information in the RDS data. This information can be used to update the clock time on the radio. RDS clock time is broadcasted once a minute. To set the clock using RDS clock data perform the following:
- Press and hold the HR and MIN buttons together for two or more seconds to update the time.
- The display will show "UPDATED" after receiving the broadcasted time data.
- If the broadcaster is not broadcasting the time data, the radio will display "NO UPDATE" and the time remains unchanged.

Steering Wheel Controls
Some audio functions are available using the steering wheel controls. The steering wheel controls consist of multiple momentary contact switches that connect a series of resistors. When a steering wheel control button is pressed, a specific resistance value is noted by the DIM. This results in a generated voltage, unique to the particular button. The DIM alerts the radio that the button has been pressed, and the radio responds, just as if the corresponding radio front panel button had been pressed.

Tape/CD Player Error Messages
The radio displays an error when any of the following occurs.
- The radio will display error codes for the tape player, integral CD player, and remote CD player.
- The radio will display the following tape player error codes for tight tape, broken tape, and wrapped tape. If these conditions are detected, the radio will switch to the radio mode and eject the tape. The error code will be displayed for 5 seconds, followed by the tuner display, then the default.
- E10-Tight tape
- E11-Broken tape
- E13-Communication problem
- E14-Wrapped tape
- The radio will display the following integral CD player error codes. If one of these problems is detected, the unit will switch to the radio mode and eject the CD. The display will show TOD, if the unit is off, or display the radio frequency for 5 seconds, then the default, if the unit is on.
- E20-Optics focus error, maybe due to moisture.
- E21-Optics loss of tracking control, maybe due to blemishes on disc.
- E22-Load/Unload motor problem.
- E23-Communication problem.
- The radio will display the following remote CD player error codes. If one of these problems is detected, the unit will switch to the radio mode. The display will show TOD, if the unit is off, or display the radio frequency for 5 seconds, then the default, if the unit is on.
- E30-Optics focus error, maybe due to moisture.
- E31-Optics loss of tracking control, maybe due to blemishes on disc.
- E34-Door Open.

XM Satellite Radio
XM is a national satellite radio service that offers up to 100 coast to coast channels including music, news, sports, talk and children's programming. XM provides digital quality audio and text information, including song title and artist name. A service fee is required in order to receive the XM service. For more information, contact XM at www.xmradio.com or call 1-800-852-9696.

Digital Radio Receiver
The radio controls communicate with the digital radio receiver via the class 2 communication circuit. The digital radio receiver sends low level audio signals to the audio amplifier.

Viewing Messages
Press the TUNE/SELECT/RCL knob while in XM mode to view various pieces of information related to the current song or channel. By pressing TUNE/SELECT/RCL knob, you may view four different categories of information: Artist Name/Feature, Song/Program Title, Channel Category, and other Additional Information that may be broadcast on that channel. Additional Information messages may not always be available. Each of the four information types may have multiple pages of text. To reach a category, press TUNE/SELECT/RCL knob consecutively until the desired type is displayed. If there are multiple pages of text for the selected information type, the radio will automatically display all the pages for that type at a rate of approximately one page every three seconds before timing out and returning to the default display. You may override this feature by pressing the TUNE/SELECT/RCL knob to review all of the pages at your own pace.

Selecting A Program Type
The TUNE/SELECT/RCL knob can be used to scroll through the list of available program types (PROG TYPE). Press the PROG TYPE button, then turn the TUNE/SELECT/RCL knob to scroll through the available program types. When the desired program type is shown on the display, press the SCAN button. The radio will seek the next station of that type.

XM Advisory Mesages:

XM Advisory Messages