Laser echo discrimination method based on fpga

Abstract

An FPGA-based laser echo discrimination method for pulsed laser ranging. The device comprises a constant ratio timing discrimination module, a high-speed DA module, an FPGA module and a ranging module. The present invention is effective in shielding invalid stray light echoes. At the same time, it can ensure that long-distance weak signals and short-distance signals are effectively screened, so as to increase the farthest ranging distance and reduce the nearest ranging distance. At the same time, because the stray light echo is shielded, this part of the data does not need to be stored and transmitted, which can save system resources. The method can be applied to laser ranging and three-dimensional laser scanning.

Description

technical field [0001] The invention relates to laser ranging echo discrimination, in particular to an FPGA-based laser echo discrimination method for pulsed laser ranging. Background technique [0002] At present, laser ranging technology is mainly based on time-of-flight pulse ranging method and phase measurement method. Among them, the phase measurement method has high accuracy, but is affected by power and energy, and the measurement distance is short; the pulse ranging method has a long measurement distance. The farther the distance is, the higher the pulsed laser power is. When the laser enters the optical system, the reflection of the inner wall of the optical system and the optical components will inevitably generate stray light, which leads to the stray light inside the optical system. The energy increases with the power. It also gradually increases, and is recognized by the detector to generate unnecessary echoes, which will seriously affect the screening effect o...

AI Technical Summary

Problems solved by technology

Among them, the phase measurement method has high precision, but due to the influence of power and energy, the measurement distance is short; the pulse ranging method has a long measurement distance

The farther the distance, the higher the power of the pulsed laser is required, and when the laser enters the optical system, the reflection of the inner wall of the optical system and the optical components will inevitably generate stray light, which leads to the increase of the power of the stray light inside the optical system. It also gradually increases and is recognized by the detector to generate unnecessary echoes, which will seriously affect the screening effect of the echoes of real targets

[0003] "Laser and Infrared" Issue 11, 2007 "Research on High-precision Laser Ranging Technology" introduced a constant-ratio timing discriminator circuit. The constant-ratio timing discriminator uses a constant threshold. In this way, if the stray light energy is strong, It is necessary to increase the threshold, then the weak signal in the distance cannot be discriminated; if the threshold is lowered, the stray light echo is discriminated, and the near echo within the echo pulse width cannot be discriminated

like figure 1 , in the case of low threshold TH1, the short-distance echo No. 4 cannot be discriminated; in the case of high threshold TH2, the distant No. 2 echo cannot be discriminated

It can be seen that with the method of constant threshold, the measurable minimum distance and maximum distance will be limited

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