Short-range signaling system

Claim 3

The method as set forth in claim 1 including the steps of sensing the presence of noise disturbances at frequencies other than said predetermined frequency and comparing said noise disturbances with said disturbances at said predetermined frequency.

Claim 4

A short range signaling apparatus comprising, in combination, an elongated ferrous signaling member supported in cantilever fashion for vibratory motion within a capsule, a second ferrous member mounted in said capsule in spaced relation from the free end of said elongated member, means for deflecting the free end of said elongated signaling member into contact with said second member, a source of residual magnetism associated with said members for holding said elongated member in contact with said second member, a source of magnetic initiating field opposed to said residual field for releasing said elongated member from said second member such that the elongated member thereafter freely vibrates to produce a magnetic signaling disturbance into the air surrounding said signaling member having a predetermined frequency, and means remote from said capsule for detecting said magnetic signaling disturbance having said predetermined frequency.

Claim 5

A short range signaling apparatus comprising, in combination, an elongated ferrous signaling member supported in cantilever fashion for vibratory motion within a capsule, a second ferrous member mounted in said capsule in spaced relation from the free end of said elongated member, means for deflecting the free end of said elongated signaling member into contact with said second member, a source of residual magnetism associated with said members for holding said elongated member in contact with said second member, a source of magnetic initiating field opposed to said residual field for releasing said elongated member from said second member such that the elongated member thereafter freely vibrates to produce a magnetic signaling disturbance into the air surrounding said signaling member having a predetermined frequency, and means remote from said capsule for detecting said magnetic signaling disturbance having said predetermined frequency.

Claim 6

A device as set forth in claim 3 wherein said source of residual magnetism comprises a magnet attached to said capsule.

Claim 7

A device as set forth in claim 3 wherein said source of residual magnetism comprises the remanent magnetism of at least one of said members.

Claim 8

A device as set forth in claim 3 wherein said second member comprises a second elongated member mounted cantilever fashion within said capsule and having a free end overlapping and spaced from said first-named elongated member.

Claim 9

A device as set forth in claim 6 wherein both of said members are adapted to vibrate at substantially said predetermined frequency.

Claim 10

A device as set forth in claim 3 wherein said means for deflecting said elongated member comprises an external source of a magnetic field cooperative with said residual field for creating a magnetic attraction between said members sufficient to deflect said elongated member into contact with said second member.

Claim 11

A combination as set forth in claim 3 wherein said means for detecting magnetic disturbance having a predetermined frequency comprises, in combination, an antenna or pickup coils, an amplifier coupled to said antenna, a first band-pass filter coupled to the output of said amplifier and tuned to a frequency lower than said predetermined frequency, a second band-pass filter coupled to the output of said amplifier and tuned to said predetermined frequency, a third band-pass filter connected to the output of said amplifier and tuned to a frequency higher than said predetermined frequency, first, second and third rectifying means coupled to the outputs of said first, second and third filters respectively, said first and third rectifying means producing control signals of one polarity and said second rectifying means producing a control signal of the opposite polarity, and means coupled to the outputs of said filters for summing said control signals to produce a sum signal the polarity of which indicates the presence of said magnetic disturbances.

Claim 12

The combination as set forth in claim 9 wherein said antenna is positioned adjacent an exitway from a protected enclosure, wherein said source of a magnetic initiating field is positioned adjacent said exitway, and wherein an alarm device is coupled to said summing means such that it is actuated in response to the presence of a sum signal having said opposite polarity.

Claim 15

The method as set forth in claim 11 including the Steps of sensing the presence of noise disturbance at frequencies other than said predetermined frequency and comparing said noise disturbances with said signal at said predetermined frequency.

Claim 16

A short range signaling apparatus comprising, in combination, a ferrous signaling member mounted for vibratory movement within a housing, said member having a predetermined mechanically vibratory resonant frequency, means for initiating the vibration said ferrous signaling member such that said member thereafter freely vibrates at said resonant frequency to radiate a magnetic signal into the air surrounding said member at said predetermined frequency, and means for detecting the presence of said magnetic signal at a position remote from said ferrous member.

Claim 17

A short range signaling apparatus comprising, in combination, a ferrous signaling member mounted for vibratory movement within a housing, said member having a predetermined mechanically vibratory resonant frequency, means for initiating the vibration said ferrous signaling member such that said member thereafter freely vibrates at said resonant frequency to radiate a magnetic signal into the air surrounding said member at said predetermined frequency, and means for detecting the presence of said magnetic signal at a position remote from said ferrous member.

Claim 18

The apparatus as set forth in claim 13 wherein said means for detecting the presence of said magnetic signal comprises, in combination, an antenna, an amplifier coupled to said antenna, a first band-pass filter coupled to the output of said amplifier and tuned to said predetermined frequency, a third band-pass filter connected to the output of said amplifier and tuned to a frequency higher than said predetermined frequency, first, second and third rectifying means coupled to the outputs of said first, second, and third filters respectively, said first and third rectifying means producing control signals of the opposite polarity, and means coupled to the outputs of said filters for summing said control signals to produce a sum signal the polarity of which indicates the presence of said magnetic disturbance.

Claim 19

The apparatus as set forth in claim 14 wherein said antenna is positioned adjacent an exitway from a protected enclosure, wherein said means for initiating vibration is a source of magnetic initiating field positioned adjacent said exitway, and wherein an alarm device is coupled to said summing means such that it is actuated in response to the presence of a sum signal having said opposite polarity.