The phase locked loop system has a lock frequency range which decreases its width when {HEAD ~ the level} of the input angle modulated wave is below {TAIL ~ a predetermined level} 
The phase locked loop system has a lock frequency range which decreases its width when { HEAD ~ the level } of the input angle modulated wave is below { TAIL ~ a predetermined level }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL