Abstract: An on-vehicle receiving system for optimizing the receiving performance of a radio receiver and a remote controlled receiver, whereby a remote-controlled receiver and a radio receiver share an on-vehicle antenna. A key detector for detecting whether an ignition key is fitted into a key cylinder of the vehicle is employed and a selector switch for connecting the on-vehicle antenna selectively to the remote-controlled receiver or the radio receiver are incorporated. When the key detector detects that the ignition key is fitted into the key cylinder, the selector switch selects the radio receiver. When it is detected that the ignition key is not fitted into the key cylinder, the remote-controlled receiver is selected. In one embodiment, a remote-controlled receiver and a radio receiver share not only an on-vehicle antenna but also part of receiving equipment. The remote-controlled receiver and radio receiver can also share the frequency and modulation form employed.

Abstract: An electromagnetic proximity sensor for car security systems includes an electromagnetic wave radiating section adapted to oscillate in a predetermined high frequency range to outwardly radiate an electromagnetic wave; a clutter component extractor for extracting a low frequency clutter component generated in the electromagnetic wave by the approach or movement of an object; a level comparing section, to which is supplied a low frequency clutter component signal corresponding to the extracted low frequency clutter component so as to be compared with a predetermined reference level and which is adapted to emit a sensor signal when the clutter component signal supplied is beyond a predetermined level; and an oscillating operation intermitting section, to which is supplied a pulse signal of a variable duty ratio and of a frequency higher than that of the low frequency clutter component and which is adapted to intermit the oscillating operation of the electromagnetic wave radiating section on the basis of this pu

Abstract: Microcomputers or microprocessors are required to be reset after supply of a power source voltage to the microcomputers or microprocessors is interrupted due to the replacement of the microcomputers. A time constant circuit generates a reset signal from a capacitor of the time constant circuit after a predetermined time has passed since the source voltage was applied to the microcomputers. A discharging circuit is connected to the time constant circuit, and rapidly discharges the charge stored in the capacitor of the time constant circuit after the supply of the source voltage is interrupted.