Mathematical Analysis and Modelling of a Novel Photonic based FMCW Signal Generation for Long Range Radar Applications

Modern day radars require multi-function capabilities to address the needs with growing threat scenarios. This demands systems with both short and long range detection supported with other multi-function capabilities including imaging. Conventionally, for radar applications with short range detection, Frequency Modulated Continuous Wave (FMCW) radar is one of the popular solutions. But recently, research has been conducted on using FMCW radar for long rage detection with high resolution based on photonics techniques. This is not possible with RF counterparts due to the existing bandwidth limitations and other related constraints. Few photonic techniques such as heterodyning [9] and frequency-to-time mapping have been researched upon and found out that these methods have few drawbacks like signal degradation and poor tunability. This paper proposes a novel method for the generation of large bandwidth and high sweep rate FMCW signals for long range detection based on the application requirements. The FMCW generation includes sawtooth as well as triangular chirps as per the target scenario requirements. The paper also brings out the mathematical analysis of the proposed hardware design used for the generation of the chirp signals. The analysis is supported with modelling results to obtain various multi-chirp patterns having a sweep bandwidth of 4GHz at a central frequency of 79GHz with a chirp time of 100ns. The proposed method can be extended to other fields like automobile and bio-medical applications.