Ultrasonic transducer, ultrasonic reversing radar

In fact, in the electromagnetic wave, only the microwave is suitable for the vehicle reversing radar, otherwise the wavelength is longer than the car, and its accuracy cannot guarantee the safety of reversing. Below I will use microwaves to represent electromagnetic waves.
The reversing radar has an adaptive ranging range of 0.1 to 3 meters. The best distance measurement scheme for this distance is ultrasonic. The reasons are as follows:The more popular ranging solutions are as follows:ultrasonic proximity sensor, electromagnetic waves, lasers, infrared.

1. Laser and infrared, the detection surface is too small, the probe needs an optical window, is easily blocked by sediment, and is not ideal at close range, so it is excluded;
2. the microwave, its characteristics are somewhat like light, but not as easy to control as light. Usually the microwave probe for ranging is the FMCW radar, which is neither waterproof nor planar. The housing is a metal of the vehicle can be completely blocked, the microwave reflection, microwave probe and therefore do not require a carbon-containing nonmetallic material 'window', colloquially requires a plastic waterproof cover, and spray paint can (paint containing C), but can not use a metal-containing paint, this way, in which it did not look good, and fragile breakable fear of being blocked sediment. Moreover, low microwave loss in the air, and to transmit and receive a large angle, which makes it possible to detect a microwave sensor 3 meters, which can be easily reflected energy to a few hundred meters without dissipation, which is likely to cause the vehicle between interference; Furthermore, since the electromagnetic wave in the air close to the speed of light, when the measuring distance is less than the target 0.6 m, the conventional microwave distance sensor to work close to the limit, with multiple reflected energy around the disturbance this reversing radar is difficult to ensure the normal operation, while recently detected a distance of 0.6 m for reversing radar is not competent. Of course, these problems can be solved by technical approach to international cutting-edge, but the cost to increase 1 to 3 0 later. In short, in terms of comprehensive effects, cost and reliability, it is difficult for microwaves to compete with ultrasonic waves.

3.the biggest disadvantage of ultrasonict transducer for distance
 is that the detection angle is too small, a car needs to be installed at different angles, in addition, it is better than the above several solutions,disadvantages are ultrasonic transducer: 

1, waterproof, dustproof .A small amount of sediment blocking is also possible; 

2, a metal probe can be combined with the car body shell; 

3, usually suitable for detection within 3 meters, due to its large air loss, the detection angle is small, so between vehicles The interference is small; 

4, the minimum monitoring distance can reach 0.1-0.3 meters;

 5, the cost is not high.