Audi Workshop Service and Repair Manuals > A4 Mk3 > Vehicle electrics | System description - adaptive cruise control | Self diagnosis, V.A.G Inspection Service | General notes on "adaptive cruise control" (ACC)

Technical data > < Description of dynamic noise compensation

General notes on „adaptive cruise control“ (ACC)

Requirements for adaptive cruise control

The following information is required for the control:

Distance to vehicle in front

The time span between the transmission of the signal and the receipt of the reflected signal components depends on the distance to the object.

In other words, the further away an object or vehicle is, the longer it takes to receive the signal echo.

Speed of vehicle in front

If the distance to the vehicle in front is reduced, the frequency of the reflected beam is increased.

If the distance to the vehicle in front is increased, the frequency of the reflected beam is reduced.

Distance to vehicle in front	Time span between transmitted and received signal	Frequency
Remains constant	Time remains constant	Remains constant
Is increased	Time is increased	Is reduced
Is reduced	Time is reduced	Is increased

This frequency shift is evaluated by the electronics and is used to calculate the speed.

Position of vehicle in front

The radar signal propagates outwards in the shape of a cone.

The intensity of the signal decreases as it gets further away from the transmitter in the longitudinal and transverse directions.

In order to determine the position, it is also necessary to know the angle at which the vehicle in front is moving in relation to the host vehicle.

A radar with four beams is used for this purpose.

The angle information is provided by the ratio between the amplitudes (= signal strength) of the received (i.e. reflected) signals from the individual radar beams.

Vehicle electrics
System description - adaptive cruise control
Self diagnosis, V.A.G Inspection Service
General notes on "adaptive cruise control" (ACC)

Technical data > < Description of dynamic noise compensation

Audi Workshop Service and Repair Manuals

A4 Mk3

Vehicle electrics System description - adaptive cruise control Self diagnosis, V.A.G Inspection Service General notes on "adaptive cruise control" (ACC)

Vehicle electrics System description - adaptive cruise control Self diagnosis, V.A.G Inspection Service General notes on "adaptive cruise control" (ACC)

Vehicle electrics
System description - adaptive cruise control
Self diagnosis, V.A.G Inspection Service
General notes on "adaptive cruise control" (ACC)

Vehicle electrics
System description - adaptive cruise control
Self diagnosis, V.A.G Inspection Service
General notes on "adaptive cruise control" (ACC)