Center frequency(KHz) | 40.0KHz±1.0KHz |
Transmitting Sound Pressure Level(dB) | 117min(0dB=0.02mPa) |
Receive Sensitive(dB) | -68min(0dB=1V/μbar) |
-6 dB Directivity (deg) | 50° |
Ringing | ≤1.2ms |
Function | Transmitter / Receive |
capacitance (pF) | 2200±25﹪ |
Allowable Input Voltage(Vp-p) | 150(40KHz) |
Operating Temperature (℃) | -40～80℃ |
Storage Temperature (℃) | -40~+85℃ |
Metals of case | Aluminum |
Terminal | PIN |
Weight(g) | 2.6g |
Car Reversing Aid Systems, the full name of "Reversing Collision Avoidance Radar," also known as "Parking Assist," is a vehicle parking safety aid that informs the driver about obstacles around with sound or more intuitive displays The situation caused by the driver's parking and start-up of the vehicle was lifted, and the driver was relieved of the blind spot of the view and the blurred vision to improve the safety.
The parking sensor only needs to work while the car is reversing, providing the driver with the information behind the car. As the car reversing speed slower, compared with the sound speed can be considered as a car is static, so in the system can ignore the Doppler effect. In many ranging methods, the pulse distance measurement method only needs to measure the round trip time of the ultrasonic wave between the measurement point and the target, and the implementation is simple. Therefore, the system adopts this method.
As shown in Figure 1, the driver turns the handle to the reverse gear and the system automatically starts. The ultrasonic transmitting module transmits the ultrasonic signal of 40 kHz backward and is reflected by the obstacle and collected by the ultrasonic receiving module for amplification and comparison. The AT89C2051 The signal into the display module, while triggering the voice circuit, issued a simultaneous voice prompts, when the distance to the obstacle is less than 1m, 0.5m, 0.25m, a different alarm sounds to remind the driver to stop.
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