General radar transmission codes that minimize measurement error of a static target

The variances of matched and sidelobe free mismatched filter estimators are given for arbitrary coherent targets in the case of aperiodic transmission. It is shown that mismatched filtering is often better than matched filtering in terms of estimation accuracy. A search strategy for finding general transmission codes that minimize estimation error and satisfy constraints on code power and amplitude range is then introduced. Results show that nearly perfect codes, with performance close to a single pulse with the same total power can be found. Also, finding these codes is not computationally expensive and such codes can be found for all practical code lengths. The estimation accuracy of the newly found codes are compared to binary phase codes of similar length and found to be better in terms of estimator variance. Similar transmission codes might be worth investigating also for sonar and telecommunications applications.