Аңдатпа
In this paper, we present a new approach for chirp and phase normalization for enhancing linewidth and beat-signal coherence in a multi-chirp microwave photonic radar system. The proposed Beat Signal Chirp and Phase Normalization (BSCPN) technique introduces adaptive corrections to inter-chirp phase and chirp-rate drift of the received signal, effectively aligning multiple successive chirps and eliminating phase discontinuities in the post-processing. This normalization enables coherent integration across chirps, yielding improved range profiles and detection fidelity. Beat Signal Chirp Normalization (BSCN) and full-BSCPN methods were implemented for detecting multi-target configurations for two-, three-, and four-chirp photonic radar systems with varying object spacings of 3.5 cm, 3.0 cm, and 2.7 cm. Through post-processing compensation of chirp-to-chirp phase discontinuities and chirp normalization, the results show an improvement in linewidth reduction of up to 70-75%, an improvement in range accuracy to sub-centimeter levels, and a peak sidelobe level (PSL) reduction of approximately 6-12 dB, depending on the multi-chirp configuration. Additionally, the four-chirp radar operation (73-74 GHz, 74-75.5 GHz, 75.5-78 GHz, 78-80 GHz; each with a duration of 0.375 μs) achieves up to 0.22 cm range resolution and a 6-8 dB PSL reduction in comparison to the uncompensated case, confirming the effectiveness of BSCPN for higherorder multi-chirp operation. These results demonstrate that receiver-side post-processing normalization through BSCPN restores inter-chirp beat coherence, reflected in aligned beat-frequency components, reduced linewidth, and improved range resolution in multi-chirp photonic radar systems. Furthermore, additional analyses of computational complexity and processing latency, along with low-SNR robustness, have been incorporated to enhance the practical applicability of the proposed framework.