Aiming at the problem that the laser coherent detection system is easy to be annihilated in the noise in the long-distance and complex environment, resulting in the system unable to extract effective information, In this paper, the pulse compression theory and matched filter principle are analyzed, and a target high-precision matched filter LFM system model suitable for laser coherent detection is proposed, by transmitting a linear frequency modulation signal, combined with the matched filter algorithm to process the echo signal, realizes the target distance solution under the condition of low signal-to-noise ratio. At the same time, the influence of FM bandwidth on the multi-target extractionability under different SNR is studied, and the FM bandwidth-ranging accuracy model is established. Compared with the ordinary windowing algorithm, by increasing the system FM bandwidth, it can be effective in extremely low signal-to-noise ratios. Extract multi-target distance values. The simulation results show that under the condition of -40 dB signal-to-noise ratio, setting the frequency modulation bandwidth to 4 GHz can effectively achieve multi-target detection, and the ranging accuracy can reach 4.5 mm.
Aiming at the problem of high laser power requirements in the long-distance application of LiDAR, combined with the advantages of long-distance detection capability of linear frequency modulation continuous wave, this paper proposes a pulse compression real-time processing technology based on LiDAR data module FPGA. Matlab software is used for parameter simulation, and then FPGA algorithm is used to implement the real-time frequency domain pulse compression processing. By comparing verilog simulation and Matlab simulation results, the feasibility of digital pulse compression real-time processing system design in this paper is verified.
Nowadays, laser ranging is widely used in industrial and security fields. As one of the most well-known pulse laser detection system, Lidar is a much effective equipment for environmental recognition. Currently, research on autonomous and smart vehicles technology has been growing exponentially in recent years by integrating more and more smart hardware or software inside. Most studies are almost based on non-real-time operating system with random delays, which leads to lag and inaccuracies in the received data. Based on a self-developed three-dimensional Lidar, a smart embedded system for real-time data transmission on the FPGA Zynq is proposed. The real-time signal acquisition and transmission system is implemented and verified in the three-dimensional imaging experiments system. In this system, verilog code is applied for Lidar data control acquisition and transmission. C/C++ code is used for data calculation and uploading the point cloud data to the computer through the network to realize the real-time display of point cloud. Experimental results demonstrate that the Lidar data are correctly read by the FPGA board. In addition, the real time data acquisition meets the requirements of control and real time data acquisition and procession at 20fps. The proposed approach provides a very useful basic platform for many applications using Lidar as a sensor and will improve their detection accuracy.
In view of the current booming LiDAR systems and the trends of the future market, this paper first introduces the mainstream manufacturers in real-time sensing LiDAR, as well as their products. Combining with different requirements in application, characteristics, and current situation of different LiDAR technical systems. Then, the research progress in railway perimeter real-time monitoring of the LiDAR team from the Institute of Microelectronics is presented. Finally, the application trend and development prospect of real-time sensing LiDAR are summarized and forecasted. To meet the evolving demands, real-time sensing LiDAR will be further advanced to low cost, high performance, product seriation, device miniaturization, fixation and multi-source integration, etc. The system has been applied to protect railway security.
As a classic radar signal processing method, pulse compression technology can effectively increase the measurement distance while ensuring the ranging resolution, so as to achieve long-distance high-precision measurement. Waveform modulation techniques commonly used for pulse compression include linear frequency modulation and phase code modulation. In this paper, we proposed a method of laser ranging technology based on pulse compression, briefly analyzing two waveform modulation techniques and exploring the relationship between modulation bandwidth and ranging accuracy based on the linear frequency modulation ranging model. The results indicated that the ranging accuracy fluctuated greatly when the modulation bandwidth was changed. The measurement error would be stable within 10mm when the modulation bandwidth was on the order of GHz. The method would be expected to provide a certain reference for the choice of laser modulation bandwidth in the field of long-distance high-precision laser measurement.
Segmented planar image detector for electro-optical reconnaissance (SPIDER) is a new type of lightweight and high-resolution computational imaging system that has applications in fields such as remote sensing terrain exploration, high precision military detection, and remote environmental monitoring. Currently, the lens combination methods used in the SPIDER system misses a large amount of the spatial-frequency information detected by each spoke’s lens array. The SPIDER imaging principle was analyzed with a particular focus on understanding the effect of the lenslets combination method on image quality. To optimize the quality of reconstructed images, we have proposed a pseudo two-layer parity configuration. To compare the quality of image restoration using the pseudo two-layer parity combination methods with previously existing methods, the entire imaging process was numerically simulated and the peak signal-to-noise ratio of each reconstructed image was estimated. The simulation demonstrated that the reconstructed image obtained using the pseudo two-layer parity combination was more similar to the original image and exhibited a higher image quality than the images reconstructed using other methods. These results indicate that the optical structure of the SPIDER system can be optimized by implementing the pseudo two-layer parity aperture combination method and this provides theoretical support for the further development of the SPIDER system.
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