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