Tracking of Noncooperative Airborne Targets Using ADS-B Signal and Radar Sensing

Table 1

Effects of random biphase modulation on correlation results.

Messages	Modulation
	PPM	PPM with random biphase PM
		Same phase; (no phase shift)	Inverted phase; (180° phase shift)
(1, 1) or (0, 0)	Positive; sum-product	Positive; sum-product	Negative; sum-product
(1, 0) or (0, 1)	Zero; sum-product	Zero; sum-product	Zero; sum-product