R Effect:

Wideband FM : Transmitted with deviation ratio of 5/1, ( +90kHz ), but the final filtered audio has a 15kHz bandwidth. Phase Locked Loop: Used to track a signal in a wide noise bandwidth to yield a signal with a low noise bandwidth. DSSS Chip Rate ( broadband )/ Signal BW ( narrow ) is called processing gain. 1.25 Mb/s chip rate and 12.5 kHz audio filter yields a "processing gain" of 100/1 Correlation A number of IF cycles after detection are integrated to result in a narrower bandwidth than the original IF bandwidth. M-ary-OFSK A broad bandwidth is required for transmission, but the individual symbols are detected in a narrow Nyquist bandwidth.