## 2 FMCW LiDAR
### FMCW LiDAR Key Parameters
#### 2.3.8 Technical Limitations of FMCW LiDAR and Their Impact on Key Parameters  
Although the FMCW LiDAR technology is relatively mature, researchers continue to explore methods by which to address its limitations and advance the technology further. We have systematically summarized and deeply analyzed the key performance parameters of FMCW LiDAR, demonstrating how these parameters collectively shape the overall performance of the LiDAR system, as shown in Table 3.  
From the analysis in Table 3, the metrics of FMCW LiDAR are mainly limited by the performance parameters of the light source. Therefore, current research on FMCW LiDAR focuses on exploring more-advanced light source technologies to improve the overall stability of the system. By improving the design of the laser light source and receiver and developing more advanced ambient noise filtering algorithms, the environmental adaptability of the system can be significantly improved, and new types of laser light \begin{table}
\begin{tabular}{c c c} \hline \hline
**Key Parameters** & **Factor** & **Performance Interactive** \\ \hline \multirow{3}{*}{Detection distance and accuracy} & Coherence length of the transmitted optical signal; sensitivity of the receiver; atmospheric conditions, etc. & Increasing detection range often requires a compromise in detection accuracy, and vice versa \\ \hline \multirow{3}{*}{Distance resolution and ranging accuracy} & Mainly affected by modulation waveform and bandwidth & Wider bandwidth enhances range resolution but may require more complex signal processing techniques to maintain ranging accuracy \\ \hline \multirow{3}{*}{Angular resolution} & Influenced by the aperture of the optical system at the transmitter and receiver, etc. & Improving angular resolution requires reducing the divergence angle and increasing the aperture of its receiving system \\ \hline \multirow{3}{*}{Random noise} & Influenced by internal system components, noise entering the system through the receiver, atmospheric transmission losses, etc. & Improved signal processing algorithms or optimized spectrum analysis techniques \\ \hline \multirow{3}{*}{FM linearity} & Influenced by the stability and quality of the laser light source & Non-linear FM leads to measurement errors \\ \hline \multirow{3}{*}{Accuracy of distance and angle measurements} & Affected by linearity and system calibration of light source frequency modulation & Accurate distance measurement is fundamental to accurate velocity measurement, with both complementing each other \\ \hline \multirow{3}{*}{Narrow linewidth of light source} & \multirow{3}{*}{Light source quality and stability} & Narrow linewidth of the light source improves signal clarity and overall system performance, which, in turn, affects the accuracy of distance and speed measurements \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Summary of the function of each performance parameter, its influencing factors, and their interactions. Figure 9: System architecture of the autocorrelation linewidth test. sources, such as ultrafast lasers and quantum dot lasers, can be explored to provide a more stable and wider frequency modulation range. OPA technology allows for laser beams to be scanned electronically without mechanical moving parts. This technology can significantly reduce system size and weight, improve reliability, and potentially reduce costs. In addition, improvements in OPA technology also help improve angular resolution and scanning speed. To optimize these key parameters, researchers are currently developing more-efficient signal processing algorithms to improve modulator and receiver performance; more precise wavelength control and high-speed modulation techniques are used to significantly improve radar performance, and it should be noted that, for intracavity modulated continuous-wave laser sources, achieving a high tuning rate and narrow linewidth simultaneously presents an inherent trade-off. A longer resonant cavity facilitates the attainment of a narrower linewidth but compromises the tuning speed.