Phase measurements using direct conversion AM radio navigation

This paper presents a number of approaches for precision navigation using AM broadcasts and analog phase measurement techniques. By mixing signals down to a low intermediate frequency (IF) and locking on with a phase lock loop (PLL), phase differences can be measured with /spl plusmn/0.5/spl deg/ accuracy. This provides /spl plusmn/0.32 meters range accuracy with a 1300 kHz AM radio signal.