When {HEAD ~ the level} of the input angle modulated wave drops abruptly, {TAIL ~ the width} of the lock range abruptly becomes narrow, and the PLL 19 becomes unlocked and ceases to make PLL operation 
When { HEAD ~ the level } of the input angle modulated wave drops abruptly , { TAIL ~ the width } of the lock range abruptly becomes narrow , and the PLL 19 becomes unlocked and ceases to make PLL operation
OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH