Control Module

Fig 1: Identifying AM/FM Tuner Module (AFM)

Courtesy of VOLVO CARS OF NORTH AMERICA.

The system for radio reception consists of

antenna system for AM/FM
AM/FM tuner module (AFM)
antenna amplifier.

The AM/FM tuner module (AFM) has the task of receiving radio signals for the AM and FM wavebands.

The radio signals received by the antenna are decoded and transmitted to the AM/FM tuner module (AFM).

The signals contain information about (see below):

alternative frequencies (AF)
program identification code (PI)
program channel name (PS)
traffic program (TP)
traffic messages (TA)
increased program information (EON)
program type (PTY).

AM/FM tuner module (AFM) has a 5-band equalizer integrated in the unit. The equalizer controls the frequency reproduction from the received radio signals.

The antenna amplifier is supplied with power by the AM/FM tuner module (AFM), via phantom power supply (coaxial cable), with a nominal 11 ± 0.5 V. If the vehicle is equipped with RTI (Road Traffic Information) the power supply is via the traffic message channel module (TMC). The diagnostic trouble code (DTC) is stored and the system is shut down if the voltage exceeds 13.5 ± 0.5 V. The voltage is regulated to the battery capacity if the battery voltage is below 10.5 V.

When the ignition is switched off the power consumption of the AM/FM tuner module (AFM) must not exceed 0.1 mA.

The system can endure temperatures between -40 °C and 85 °C.

The control module checks the input and output signals through an integrated diagnostic system.

The control module communicates with directly connected components, and via MOST communication.

Alternative frequencies (AF)

Information from RDS-stations about:

which frequencies the present program can be found
program identification code (PI)
program channel name (PS).

The control module stores the information in a list. If the signal begins to fade the AM/FM receiver searches the list for a transmitter with a stronger signal. The function can be activated and deactivated by the User.

Program identification code (PI)

The code which the control module attributes to a specific program selection button. Contains the country code and the character of the network on which the program is broadcast.

Program channel name (PS).

An 8 character channel name stored in the control module.

Traffic program (TP)

Information from the RDS-station about that the station is transmitting traffic messages.

Traffic messages (TA)

The program channel transmits a traffic message code to the RDS receiver that a traffic message is to be transmitted. The RDS receiver which are set to a different channel change to the channel on which the traffic message is transmitted. The traffic message is used to inform the User of relevant road conditions such as road works, accidents etc. After the message has been received the control module returns to the source that was activated before the interruption. The function can be activated and deactivated by the User.

Increased program information (EON)

Signals sent by RDS-stations containing information about program services such as:

alternative frequencies (AF)
traffic messages (TA)
program channel name (PS)
program type (PTY) on frequencies within the same radio network.

Program type (PTY)

Description of what sort of program types the channel is currently broadcasting. For example news, music etc. There are 31 different definitions of program type (PTY1 - PTY31). The user can activate/deactivate all program types except PTY31 (alarm) which is preset and cannot be deactivated.