RADAR UNIT
id151100001000
Purpose
• The radar unit emits milimeter waves*1 in front of the vehicle and detects a target object in front of the vehicle based on the reflected waves. The radar unit controls the following systems based on target information.
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― Mazda radar cruise control (MRCC) system
― Smart brake support (SBS) system
― Distance recognition support system
*1 :These radio waves, at a frequency of 30—300 GHz and a wavelength of 1—10 mm {0.04—0.39 in}, possess a property in which the effect of rain and dirt is comparatively small and insusceptible to interference of other radio waves.
Functions
• The radar unit emits milimeter waves at an angle of
approx. 8° (total 16°) left and right of center from the front of the radar unit, and detects objects
up to approx. 180 m {590 ft 7in} from the front of the vehicle.
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Note
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• Under the following conditions, the radar unit may not be able to detect vehicles ahead or obstructions correctly and each system may not operate normally.
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― The rear surface of a vehicle ahead does not reflect radio waves effectively, such as an unloaded trailer or an automobile with a loading platform covered by a soft top, vehicles with a hard plastic tailgate, and round-shaped vehicles.
― Vehicles ahead with low vehicle height and thus less area for reflecting radio waves.
― Visibility is reduced due to a vehicle ahead casting off water, snow, or sand from its tires and onto your windshield.
― The luggage compartment is loaded with heavy objects or the rear passenger seats are occupied.
― Ice, snow, or soiling is on the front surface of the front emblem.
― During inclement weather such as rain, snow, or sand storms.
― When driving near facilities or objects emitting strong radio waves.
• Under the following conditions, the radar unit may not be able to detect vehicles ahead or obstructions.
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― The beginning and end of a curve.
― Roads with continuous curves.
― Narrow lane roads due to road construction or lane closures.
― The vehicle ahead enters the radar unit's blind spot.
― The vehicle ahead is running abnormally due to accident or vehicle damage.
― Roads with repeated up and down slopes.
― Driving on poor roads or unpaved roads.
― The distance between your vehicle and the vehicle ahead is extremely short.
― A vehicle suddenly comes close such as by cutting into the lane.
• If the battery power is weak, the system may not operate correctly.
• The radar unit emits radar, calculates the target position, distance from the vehicle, and relative speed based on the reflected waves and the signals (vehicle speed signal, steering angle signal, yaw rate signal, vehicle wheel speed signal) from the related modules.
On-board diagnostic function
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• The radar unit detects dirt and internal malfunctions of the radar unit and outputs DTCs. For DTC details, refer to On-board Diagnostic System.
Display function
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• If a system malfunction is detected, the radar unit notifies the driver of the system malfunction by performing the following controls.
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― Flashes MRCC warning light (amber)
― Activates Mazda radar cruise control (MRCC) system warning alarm
• If the radar unit performance is lowered because the sensor is dirty, the radar unit performs the following controls to warn the driver of the radar unit malfunction.
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― Displays message in multi-information display
― Activates Mazda radar cruise control (MRCC) system warning alarm
Memory function
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• The memory function stores malfunctions detected in the radar unit-related parts using the on-board diagnostic function, and the stored malfunction contents are not cleared even if the ignition is switched OFF or the negative battery cable is disconnected.
Construction
• The radar unit is built into the transmitter which emits milimeter waves and the receiver which receives the reflected waves.
• The radar unit is installed on the interior side of the radiator grille.
Operation
Target information detection
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• The radar unit emits milimeter waves from the front of the radar unit and detects a target object in front of the vehicle (vehicle ahead) by the reflected waves. The radar unit calculates the target position, distance from the vehicle, and relative speed based on the reflected waves and detects as target information.
Vehicle ahead determination
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• The radar unit estimates the travel path of the detecting vehicle based on the yaw rate signal (vehicle turning speed), vehicle wheel-speed signal, and steering angle signal sent from the related modules.
• If the radar unit detects multiple target information, it determines the target which is traveling in the estimated path of travel as the vehicle ahead.
Fail-safe
Mazda radar cruise control (MRCC) system
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• Inhibits MRCC system control.
Smart brake support (SBS) system
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• Inhibits SBS system control.
Distance recognition support system
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• Inhibits distance recognition support system control.
