Results of T/R channel analysis with coherent signal source using DDS synthesizer

The high-resolution imaging radars requires very stable and perfectly linear source of reference chirp signal. The Direct Digital Synthesis of the chirp signal can he used for that purpose. The perfect linearity of digital system can be distorted by non-uniform group delay of analog filters used in frequency up-conversion. This distortion must he measured and compensate. The paper presents the idea of distoltion measurement and selected compensation algorithms designed to work in real-time applications. All presented methods were verified with simulated and recorded data.