The main difficulties in implementing TOF radar are:

1. The first is the timing issue. In the TOF scheme, distance measurement relies on time measurement. But the speed of light is too fast, so to obtain accurate distances, the requirements for the timing system become very high. One data is that lidar needs to measure a distance of 1cm, and the corresponding time span is about 65ps. Students who are slightly familiar with electrical characteristics should know what this means for the circuit system.

2. Next is the processing of pulse signals. There are two parts here:

a) One is laser: There are almost no requirements for laser driving in triangular radar, because the measurement relies on the position of the laser echo, so only one continuous light emission is required. But TOF is not good. It not only requires pulsed laser, but also the quality should not be too bad. At present, the pulse width of the outgoing light of TOF radar is about a few nanoseconds, and the rising edge is required to be as fast as possible. Therefore, the laser drive solution of each product is There are also high and low levels.

b) The other is for the receiver. Generally speaking, the echo time identification is actually the time identification of the rising edge. Therefore, when processing the echo signal, it is necessary to ensure that the signal is not distorted as much as possible. In addition, even if the signal is not distorted, since the echo signal cannot be an ideal square wave, the measurement of different objects at the same distance will also lead to changes in the leading edge. For example, when measuring white paper and black paper at the same position, two echo signals as shown below may be obtained, and the time measurement system must measure that the two front edges are at the same time (because the distance is the same distance), which requires Special handling.

In addition, the receiving end also faces problems such as signal saturation and noise floor processing, which can be said to be full of difficulties.