EMERGENCY WARNING SYSTEM WITH RANGE CONTROL

• US 3,784,970 A
• Filed: 02/17/1971
• Issued: 01/08/1974
• Est. Priority Date: 02/17/1971
• Status: Expired due to Term

• Current Assignee: William E. Simpkin
• Original Assignee: William E. Simpkin
• Inventors: Simpkin, William E.
• Primary Examiner(s): Cooper, William C.
• Assistant Examiner(s): Myers, Randall P.
• Application Number:
  US05/116,007
• Time in Patent Office: 1,056 Days
• Field of Search: 340/32,33,31R,34,16C,16R,311 179/1SS,1VE 325/111,117 343/208,225
• US Class Current: 340/902
• CPC Class Codes: G08G 1/087 Override of traffic control, e.g. by signal transmitted by an emergency vehicle

Abstract

A range controlled emergency vehicle warning system wherein a directional radio frequency transmission has pulses superimposed thereon at a predetermined rate are concomitantly transmitted with ultrasonic pulses at the same rate. At a receiving station in a vehicle or a traffic signal controller the radio frequency signals and the ultrasonic pulse signals are received. A gate at the receiving station responsive either to the simultaneous reception, or a preselected time phasing, of the radio frequency carried pulses and an ultrasonic pulse signal generates an enable signal to cause any radio frequency carried warning advisory signal to produce a intelligible alarm such as a visual display and/or an audible alarm in the vehicle and/or to control traffic signals during approach to a given intersection. The difference in propagation velocities of the radio frequency and ultrasonic pulses fixes a time length window to limit the range of the warning zone.

Claims

1. A range controlled warning system comprising:

a. a first transmitter including means for transmitting general warning and advisory information on a radio frequency signal having long spaced apart pulses superimposed thereon, b. a second transmitter for transmitting a sequence of short ultrasonic pulses at the same rate as said superimposed pulses, c. a first receiver for receiving said radio frequency signal, d. a second receiver for receiving said ultrasonic pulses, e. gate means responsive to the reception of one of said ultrasonic pulses within the time duration of reception of one of said superimposed pulses for generation of an enable signal, f. an audio frequency sound channel, and g. a switch operable in response to said enable signal to direct said radio frequency carried advisory information to said channel for audibly reproducing said warning and advisory information.

2. The warning system of claim 1 and further comprising:

discriminator means connected to said first receiver for passing only said long pulses to said gate means.

3. The warning system of claim 1 wherein said first and second receivers are located in a vehicle having a conventional radio receiver and said switch means is operable to switch said channel between said first receiver and said radio receiver.

4. The warning system of claim 1 and further comprising:

means at said transmitter for varying the time phase between said superimposed pulses and said ultrasonic pulses to vary the range of said warning system.

5. A range controlled warning system comprising:

a. a first transmitter at a sending station including means for transmitting over a limited azimuth angle along a traffic artery general warning and advisory information on a radio frequency signal having time spaced pulses superimposed thereon, b. a second transmitter including means for transmitting ultrasonic pulses over a limited azimuth angle at the same rate as said radio frequency pUlses, c. a first receiver remote from said sending station and including means for receiving said radio frequency signal, d. a second receiver for receiving said ultrasonic pulses, e. gate means connected to said receivers responsive to a predetermined time phase relation between said radio frequency pulses and said ultrasonic pulses for generation of an enable signal, f. an audio frequency amplifier, g. a switch operable in response to said enable signal to apply said radio frequency carried warning and advisory information to said amplifier, h. speaker means for rendering audible electrical signals representative of said radio frequency carried signals, and i. a visual display actuated by said enable signal.

6. A range controlled emergency vehicle warning system comprising:

a. a first transmitter carried by an emergency vehicle and including means for transmitting a radio warning message and long radio frequency pulses at a predetermined rate, b. a second transmitter on said vehicle for transmitting short ultrasonic pulses at said rate, and c. two receivers remotely located from said transmitters in the region of the path of said vehicle to receive said message and pulses and including timing circuitry responsive to a predetermined time relationship in the arrival of a radio frequency pulse and an ultrasonic pulse at said receivers to render said warning message humanly intelligible.

7. A range controlled emergency vehicle warning system comprising:

two transmitters carried by an emergency vehicle and including selectively operable means for transmitting ahead of said vehicle at the same rate long time spaced radio frequency pulses and short ultrasonic pulses, means for varying the time phase between said radio frequency pulses and said ultrasonic pulses, and two receivers remotely located from said transmitters and including circuitry responsive to a predetermined time phase relationship between received radio frequency pulses and ultrasonic pulses to produce an emergency alarm.