Strapdown inertial navigation system requirements imposed by synthetic aperture radar

The purpose of this paper is to demonstrate a means of specifying strapdown inertial navigation system (INS) requirements from synthetic aperture radar (SAR) requirements. The latter include allowable levels for quadratic and cubic phase shift, and side lobe levels [i.e., peak side lobe ratio (PSLR) and integrated side lobe ratio (ISLR)]. When these multiple considerations produce different INS requirements, of course, the tightest governs. Results obtained constitute a technique demonstration only, and do not represent any specific mechanization. In the process of this investigation several pitfalls in common procedures were identified; these are highlighted in the discussion. A brief background description is provided in the Appendix for those unfamiliar with the analysis of SAR degradations.