Best Source Selection on Encrypted Data

Abstract

The size of the range at White Sands means multiple acquisition sites are needed to properly cover a typical vehicle trajectory. As vehicle complexity increase, the need for robust acquisition grows. Multiple acquisition sites are needed to provide as complete coverage as practical. Space Diversity combining would provide a single composite source for all the displays and recording, but this is not practical due to the large distances between acquisition sites. Instead a composite is made from the various sites by correlation on non-encrypted (or decrypted) data. The previous best source selector, a frame synch histogrammer, could produce encrypted and decrypted composites. Some of our customers have missed the encrypted composites, hence the subject is revisited to encourage development. This paper reviews post decryption correlation and then focuses on correlating on encrypted data. The encryption serves to eliminate the ambiguities that are inherent in decrypted (nonencrypted) signals. So, it may be possible to accomplish this with a small correlator. The expected performance would be similar to that of correlated composites on decrypted or unencrypted data. The typical configuration would be considerably smaller as well since only two decrypters would be needed. One decrypter alone would be insufficient and could not resolve the case where only one site has data and the remaining sites have noise. When there is no correlation the correct site cannot be resolved. Testing these compositing methods is also discussed, as a good test method also provides insight on how the compositor should work.