A Joint SAR-Communication System using Continuous Phase Frequency Shift Keying Codes and Mismatched Filtering Compression

The continuous growth of communication applications, in combination with the limited possibilities of bandwidth allocation, congests the electromagnetic spectrum. Joint radar-communication systems are thus attracting attention as they can alleviate the frequency spectrum by using the same bandwidth to perform both applications. To design such a system, continuous phase frequency-shift keying (CPFSK) codes are chosen, in order to transmit information and generate high resolution images from an airborne radar. However, the use of CPFSK codes requires sidelobe energy mitigation which is achieved by mismatched filters. The re-synthesized SAR images are created using a reconstruction algorithm from the aforementioned CPFSK codes and the mismatched filters, as well as from matched filters for the sake of analysis. These outputs are then compared using different evaluation criteria. Results of which show that the use of mismatched filtering and different messages embedded in the code phase, that maximize the data rate, provide enhanced image performance.