REAR FOCUS TYPE ZOOM LENS

摘要

PURPOSE:To detect interference to a radio by comparing the amplitude modulating component with the angle modulating component of an angle modulating signal. CONSTITUTION:An intermediate frequency signal AS which is filtered through a BPF5 is led to an FM wave detecting circuit 6 as well as to an AM wave detecting circuit 9. The FM modulating component is rectified and then supplied to a comparator 8. In the same way, the AM modulating component is supplied to the comparator 8 after rectification. The AM modulating component is then supplied to a level deciding circuit 11. A signal showing an effect of disturbance is produced to look for the next idle channel in case the input signal of the circuit 11 is larger than a prescribed level and at the same time the AM component is larger than the FM component.