Priority switching apparatus of input signal

摘要

An input signal from a Dsub connector and BNC connectors is selected by an analog switch. The frequency of horizontal and vertical synchronizing signals applied from one connector end is measured by a synchronizing frequency detection circuit. The frequencies of horizontal and vertical synchronizing signals applied from the other connector end are converted into voltage values by F/V converters. A microcomputer determines the presence of a synchronizing signal and selects an input signal from the connector end of a high priority level set in a non-volatile memory.