Much attention in recent years has been directed to apparatus which can be installed on one's vehicle to produce an alarm when it is being stolen or otherwise being subjected to unauthorized entry. On the other hand, little attention has been directed to devices which would sound an alarm when parts of the vehicle are being stolen. Hubcaps and wheel covers, for example, were relatively inexpensive and therefore not worthy of protection, but, in recent years, have become more elaborate and costlier. Some automobile owners are desirous of a device which would sound an alarm when their expensive hubcaps (this term includes wheel covers also) are being removed.
Such a device presents a particular problem since hubcaps are located on rapidly moving parts of the vehicle, rendering it impossible or at least impractical to mount sensors or the like on the hubcap or the wheel itself.
There have been vehicle alarm systems which respond to vibrations in the vehicle. The difficulty with sensing vibrations is that prior art devices have been unable satisfactorily to distinguish between vibrations which occur in normal use and those that occur when a part of the vehicle is being removed. A passing vehicle often created vibrations which would set off such prior alarm systems.