ALERTING SYSTEM RESPONSIVE TO A PLURAL TONE SIGNAL

• US 3,735,342 A
• Filed: 03/10/1971
• Issued: 05/22/1973
• Est. Priority Date: 03/10/1971
• Status: Expired due to Term

• Current Assignee: Conrad Dean Helliker, Terry E. Wilkinson
• Original Assignee: Conrad Dean Helliker, Terry E. Wilkinson
• Inventors: Helliker, Conrad Dean, Wilkinson, Terry E.
• Primary Examiner(s): Cooper, William C.
• Application Number:
  US05/122,939
• Time in Patent Office: 804 Days
• Field of Search: 340/32,33,164R,171,34 179/84VF
• US Class Current: 340/902
• CPC Class Codes: G08B 1/08 using electric transmission ; transformation of alarm signals to electrical signals from a different medium, e.g. transmission of an electric alarm signal upon detection of an audible alarm signal

Abstract

An alerting signal responsive to the receiving of a signal characterized by a sequence of tones. There is a plurality of frequency-selective circuits each operative in response to the receiving of a respective preselected one of the tones and sequence-detecting means is responsive to operation of the frequency-selective circuits in predetermined sequence for providing an output signal indicative of the receiving of said signal. Circuitry is provided for resetting the sequencedetecting means at predetermined regular periodic intervals so that the output signal is not provided unless the respective preselected tones are each received in the predetermined interval between resetting.

Claims

1. An alerting system responsive to the receiving of a signal characterized by a sEquence of tones, comprising:

a plurality of frequency-selective circuits each operative in response to the receiving of a respective preselected one of said tones;

sequence-detecting means responsive to operation of said plurality of frequency-selective circuits in a predetermined sequence for providing an output signal indicative of the receiving of said signal; and

means for resetting said sequence-detecting means at predetermined regular periodic intervals whereby said output signal is not provided unless the respective preselected tones are each received in the predetermined interval between said resettings.

2. An alerting system as set forth in claim 1 wherein said sequence-detecting means comprises a plurality of triggerable semiconductor current switching devices the main electrodes of which are all connected in a series circuit and each adapted to be triggered by a corresponding one of said frequency-selective circuits, the resetting means being operative to apply a voltage across said series circuit and to remove said voltage at said predetermined regular periodic intervals for resetting of said devices, whereby when said devices are triggered in sequence, current flows in said series circuit to provide said output signal.

3. An alerting system as set forth in claim 2 wherein the resetting means comprises a timer.

4. An alerting system as set forth in claim 3 wherein the resetting means further comprises a switching circuit, including a transistor having electrodes connected in said series circuit, said transistor being controlled by said timer.

5. An alerting system as set forth in claim 4 wherein said timer is constituted by an astable multivibrator operative to cause said transistor briefly to become nonconductive at said regular periodic intervals.

6. An alerting system for a motor vehicle and responsive to the receiving of the sound of a siren, comprising:

means for sensing sound which is present exteriorly of the vehicle;

a plurality of frequency-selective circuits interconnected with the sensing means and each operative in response to the receiving of a respective preselected tone of the sound of a siren;

sequence-detecting means responsive to operation of said plurality of frequency-selective circuits in a predetermined sequence for providing an output signal;

signalling apparatus operative in response to said output signal for providing an alerting signal interiorly of the vehicle indicative of the receiving of the sound of a siren; and

means for resetting said sequence-detecting means at predetermined regular periodic intervals whereby said output signal is not provided unless the respective preselected tones are each received in the predetermined interval between said resetting.

7. An alerting system as set forth in claim 6 wherein said means for sensing sound comprises a microphone positioned for receiving sound which is present exteriorly of the vehicle and amplifier means for amplifying the output of said microphone.

8. An alerting system as set forth in claim 6 wherein said signalling apparatus comprises a loudspeaker and oscillator means for supplying an oscillatory signal to the loudspeaker in response to said output signal thereby to generate an aural alerting signal.

9. An alerting system as set forth in claim 8 including switch means selectively operable interiorly of the vehicle for connecting said amplifier means to cause the amplified output of said microphone to be supplied to said loudspeaker.

10. An alerting system as set forth in claim 8 wherein said signalling apparatus further comprises a signal light operative in response to said output signal for providing a visual alerting signal.

11. An alerting system as set forth in claim 10 further comprising a timer and logic gate means operative in response to said output signal to effect flashing energization of said signal light under control of said timer.

12. An alerting system as set forth in claim 11 wherein sAid timer comprises an astable multivibrator and said logic gate means comprises an AND gate connected for gating an output signal from said multivibrator in response to the first-said output signal.

13. An alerting system as set forth in claim 8 wherein said oscillator means comprises a first oscillator providing a first tone frequency, a second oscillator providing a second tone frequency, first and second logic gate means respectively connected with the outputs of said first and second oscillators, and a timer connected with each said logic gate means and operative to cause alternate gating by said logic gate means of the output signals of said first and second oscillators thereby to provide an alternating two-tone aural alerting signal.

14. An alerting system as set forth in claim 13 wherein each of said oscillators and said timer is constituted by a respective astable multivibrator.

15. An alerting system as set forth in claim 13 including further logic gate means having a first input interconnected with the output of the first-said logic gate means and a second input interconnected with said sequence-detecting means, and operative to gate the output signal of the first-said logic gate means to provide said aural alerting signal in response to the output signal from said sequence-detecting means.

16. An alerting system as set forth in claim 15 wherein each of said logic gates means is constituted by a respective AND gate.

17. An alerting system as set forth in claim 6 wherein each of said frequency-selective circuits comprises a bandpass filter.

18. An alerting system as set forth in claim 17 wherein each of said filters is constituted by a passive L-C network.

19. An alerting system as set forth in claim 17 wherein said sequence-detecting means comprises a plurality of triggerable semiconductor switching devices each adapted to be triggered by an output signal from a respective bandpass filter, said devices being connected for being triggered only in said predetermined sequence.

20. An alerting system as set forth in claim 19 wherein each of said semiconductor switching devices comprises an SCR.