Photonically Generated Frequency Hopped Linear Frequency Modulated Signal Using a DFB Laser

Threats and security are critical issues in a multi-RADAR environment, which severely affect the performance metrics of a RADAR system, such as range resolution, false detection, and image quality. In a multi-RADAR environment, the issues of jamming, spoofing, and interferences should be considered for practical implementation. In this paper, we experimentally demonstrate a photonically generated frequency hopped linear frequency modulated (Ph-FHLFM) signal using injection locking in a DFB laser. For a proof of concept, we develop Ph-FHLFM with an eight-step and four-step hopping, each step having a bandwidth of 2 GHz and 1 GHz, respectively, and a total bandwidth of 8 GHz. The generated Ph-FHLFM signal detects two objects separated by 10, 5, and 2.5 cm with a maximum error of 3 mm. Further, for the proof of concept of the interference agility of the Ph-FHLFM signal, target objects are detected in the presence of an interferer, which is a conventional linear frequency modulated radar with the same/different bandwidths and chirps. Unlike in conventional LFM, the Ph-FHLFM signal overcomes the false detection and maintains a similar resolution in both scenarios, with and without an interferer.