Apparatus for warning of approaching emergency vehicle and method of warning motor vehicle operators of approaching emergency vehicles
First Claim
1. A method of warning a motor vehicle driver of an approaching, distant emergency motor vehicle having a sounding siren, the siren being characterized as emitting loud, audible frequencies that vary with time at a repetitive rate between a "low-A" frequency and a "high-B" frequency for sounding a warning siren sound, the method including the steps ofselecting only two predetermined audio frequencies A'"'"' and B'"'"' that fall within said low A and high B frequency range of a siren to be individually electronically detected and processed,providing a microphone responsive to audio signals including the frequencies between said "low-A" and "high-B" frequency range for converting the audio signals to corresponding electrical signals,amplifying the electrical signals provided by the microphone,filtering the amplified electrical signals for providing electrical signals falling only within said low A and high B frequency range and including said A'"'"' and B'"'"' frequency signals,detecting and processing the A'"'"' and B'"'"' frequency transitions for determining a preselected number of the selected A'"'"' and B'"'"' frequency transitions, andproviding a warning signal representative of an approaching emergency motor vehicle having a sounding siren upon determining the preselected number of said A'"'"' and B'"'"' frequency transitions.
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Abstract
A method and apparatus for warning a motor vehicle operator of an approaching emergency motor vehicle having a sounding siren. The method comprehends selecting two frequencies A'"'"'-B'"'"' that fall within the siren frequency range and providing a microphone for detecting the sound signals including the siren signals and filtering out the electrical siren signals by a band pass filter. The selected A'"'"' and B'"'"' frequency signals are individually detected to provide output indications thereof representative of an A'"'"'-B'"'"' frequency transition. The output indications are processed for determining the preselected number of frequency transitions and producing a warning signal representative of the approaching emergency vehicle. The warning signal is utilized to give the motor vehicle operator an audible alarm and/or a visible alarm and deenergizing the motor vehicle'"'"'s sound system.
54 Citations
29 Claims
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1. A method of warning a motor vehicle driver of an approaching, distant emergency motor vehicle having a sounding siren, the siren being characterized as emitting loud, audible frequencies that vary with time at a repetitive rate between a "low-A" frequency and a "high-B" frequency for sounding a warning siren sound, the method including the steps of
selecting only two predetermined audio frequencies A'"'"' and B'"'"' that fall within said low A and high B frequency range of a siren to be individually electronically detected and processed, providing a microphone responsive to audio signals including the frequencies between said "low-A" and "high-B" frequency range for converting the audio signals to corresponding electrical signals, amplifying the electrical signals provided by the microphone, filtering the amplified electrical signals for providing electrical signals falling only within said low A and high B frequency range and including said A'"'"' and B'"'"' frequency signals, detecting and processing the A'"'"' and B'"'"' frequency transitions for determining a preselected number of the selected A'"'"' and B'"'"' frequency transitions, and providing a warning signal representative of an approaching emergency motor vehicle having a sounding siren upon determining the preselected number of said A'"'"' and B'"'"' frequency transitions.
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8. A method of warning a motor vehicle driver of an approaching, distant emergency motor vehicle having a sounding siren, the siren being characterized as emitting loud, audible frequencies that vary with time at a repetitive rate between a "low-A" frequency and a "high-B" frequency for sounding a warning siren sound, the method is characterized as electronically detecting the distant sounding siren sounds including the steps of
selecting only two predetermined audio frequencies A'"'"' and B'"'"' that fall within the low A and high B frequency range of a siren to be individually electronically detected and processed, providing a microphone responsive to audio signals including said low A and high B frequency signals for converting the received audio signals to corresponding electrical signals, filtering the electrical signals from the microphone for providing output signals in said low A and high B siren frequency range of signals including said A'"'"' and B'"'"' signals and attenuating all other microphone signals, detecting the selected A'"'"' frequency signals from the output signals resulting from the filtering step and providing an A'"'"' output signal representative of the occurence of the A'"'"' frequency signal, detecting the selected B'"'"' frequency signals from the output signals resulting from the filtering step and providing a B'"'"' output signal representative of the occurence of the B'"'"' frequency signal, counting the number of the A'"'"' and B'"'"' output signals from the detecting steps only if they occur within a pre-selected time interval and producing an output count signal after a preselected number of said A'"'"' and B'"'"' frequency signals occur representative of a preselected number of A'"'"' and B'"'"' frequency signal transitions, and actuating a warning device in response to the output count signal.
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12. An apparatus for warning a motor vehicle driver of an approaching, distant emergency motor vehicle having a sounding siren, the siren being characterized as emitting loud, audio frequencies that vary with time at a repetitive rate between a "low-A" frequency and a "high-B" frequency when a warning siren is operative, said apparatus comprising
means for sound detecting audio signals including the audio siren sounds for converting the audio signals to corresponding analog electrical signals, amplifying means coupled to said sound detecting means for amplifying the analog electrical signals received from said detecting means, band pass filtering means coupled to be responsive to the analog electrical signals from said amplifying means and defined for transmitting the analog electrical signals having frequencies falling within the "low-A" and "high-B" siren frequencies and attentuating the remaining electrical signals, first circuit means coupled to be responsive to the electrical signals from said filtering means and constructed and defined for detecting only a A'"'"' frequency signal having a preselected frequency above said "low-A" frequency received from said filtering means and providing an output indication representative of the detection of said A'"'"' frequency signal, second circuit means coupled to be responsive to the electrical signals from said filtering means and constructed and defined for detecting only a said B'"'"' frequency signal having a preselected frequency below said "high-B" frequency and different than said A'"'"' frequency received from said filtering means and providing an output indication representative of the detection of said B'"'"' frequency signal, and means coupled to the output indications from said first and second circuit means for determining the number of frequency transitions between the A'"'"' and B'"'"' frequencies and providing an alarm signal after a preselected period representative of a preselected number of said A'"'"' and B'"'"' frequency transitions have been determined.
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15. An apparatus for warning a motor vehicle operator of an approaching emergency motor vehicle having an operative siren emitting sounds in a preselected frequency range that vary with time at a preselected rate to enable the motor vehicle operator to take appropriate action, said apparatus comprising
microphone means mountable with a motor vehicle for converting audio signals including said siren sound signals to corresponding electrical signals, filtering means coupled to be responsive to the electrical signals from said microphone means for filtering out said siren electrical signals and attentuating the remaining electrical signals, and determining means coupled to be responsive to the electrical siren signals from said filtering means for processing two different preselected frequency signals with the siren signals for determining the occurrence of a preselected number of the two siren signal transitions within a preselected time period to provide a warning signal upon the occurrence of the preselected number of said siren signal transitions.
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17. An apparatus for warning a motor vehicle operator of an approaching emergency motor vehicle having an operative siren emitting sounds in a preselected frequency band that vary with time at a preselected rate to enable the operator to take appropriate action, said apparatus comprising
microphone means mountable with a motor vehicle for converting audio sound signals including said siren sounds and non-siren sounds to corresponding electrical signals, filtering circuit means coupled to be responsive to the electrical signals for filtering out the siren electrical frequency band of signals and attentuating the non-siren electrical signals, first detector means for detecting only a first preselected A'"'"' frequency falling within the frequency signal band of the electrical signals and providing output signals representative of the detected first preselected frequency, second detector means for detecting only a second preselected B'"'"' frequency signal falling within the frequency band of the siren electrical frequency band but different from said first preselected frequency and providing output signals representative of the detected second preselected frequency, first electronic binary counting means coupled to be responsive to the output signals from said first and second detector means to count up said counting means in response to each said A'"'"', B'"'"' frequency transitions occurring during a preselected time period, said first counting means providing output count signals representative of each said A'"'"' and B'"'"' frequency transition coupled thereto, and means coupled to be responsive to the preselected count signals from said first counting means for providing an alarm signal representative of an approaching operative siren.
Specification