EMERGENCY WARNING SYSTEM

• US 3,760,349 A
• Filed: 06/21/1971
• Issued: 09/18/1973
• Est. Priority Date: 06/21/1971
• Status: Expired due to Term

• Current Assignee: Douglas W. Keister, Russel B. Leibfreid
• Original Assignee: Douglas W. Keister, Russel B. Leibfreid
• Inventors: Keister, Douglas W., Leibfreid, Russel B.
• Primary Examiner(s): Cooper, William C.
• Application Number:
  US05/155,117
• Time in Patent Office: 820 Days
• Field of Search: 340/32,33,213.1
• US Class Current: 340/902
• CPC Class Codes: G08G 1/0965 responding to signals from another vehicle, e.g. emergency vehicle

Abstract

An emergency warning system is disclosed which includes a transmitter adapted to be mounted in an emergency vehicle, such as an ambulance or police car, and a receiver adapted to be mounted in another vehicle such as a private automobile. The transmitter emits coded signals in response to actuation of the vehicle'"'"''"'"'s siren or other emergency device, and the receiver responds to receipt of only the coded transmitted signals when the emergency vehicle and another vehicle are in close proximity to provide visual or audio signals to the driver of another vehicle to warn him of the proximity of the emergency vehicle. A switch is provided in the receiver to override the audio warning signal received by the driver of another vehicle, and the switch is automatically reset by loss or reduction of signal from the transmitter of the emergency vehicle.

Claims

1. An emergency waRning system comprising, in combination:

a transmitter adapted to be mounted in an emergency vehicle, said transmitter including means for transmitting a radio frequency carrier signal including a distinctly coded signal having at least two distinctive coding characters to represent proximity of a single emergency vehicle;

means for modulating said radio frequency signal with at least two tone signals to provide said at least two distinctive coding characters;

a plurality of receiving means each adapted to be mounted in another vehicle for receipt of transmitted signals from said transmitting means, each of said receiving means including decoding means for decoding said distinctly decoded signal when received, said decoding means including means to provide a separate signal responsive to each of said distinctive coding characters, and means responsive to said separate signals when at least one of said signals follows a previously generated, of said signals within a predetermined time period to provide an alarm control signal;

a distinctive alarm mechanism; and

means responding only to said alarm control signal to actuate said alarm mechanism whereby actuation of said alarm mechanism is indicative of proximity of said emergency vehicle to said another vehicle.

2. The system of claim 1 wherein said alarm mechanism includes an audio alarm and further including switch means for turning off said audio alarm at any time during receipt of said distinctly coded signals, and means responding to the level of said received distinctively coded signals to automatically reset said switch means when said level is below a predetermined level.

3. The system of claim 1 wherein said alarm mechanism includes both an audio alarm and a visual alarm.

4. The system of claim 2 wherein said alarm mechanism further includes a visual alarm.

5. The system of claim 1 wherein said transmitted distinctively coded signal includes successive tone signals of different frequency each transmitted for a predetermined duration, and said decoding means responds to receipt of said successive tone signals in a predetermined sequence to provide said alarm control signal.

6. The system of claim 5 wherein said decoding means includes first circuit means responding only to receipt of the first of said successive tone signals to provide a first signal having a duration longer than said first of said successive tone signals, second circuit means responding only to receipt of a different successive tone signal to provide a second signal overlapping with said first signal, and means responding to said first and second signals to provide said alarm control signal.

7. The system of claim 6 wherein said decoding means includes a first AND circuit having its inputs connected respectively to the outputs of said first and second circuit means, and providing a third signal in response to both of said first and second signals;

an OR circuit having its inputs respectively connected to the outputs of said first and second circuit means and providing a fourth signal in response to one of said first and second signals, and a second AND circuit connected at its inputs respectively to the outputs of said first AND and said OR circuit and responding to both said third and fourth signals to provide said alarm control signal.

8. The system of claim 7 wherein said alarm mechanism includes an audio alarm and further including switch means for turning off said audio alarm at any time during receipt of said distinctly coded signals, and means responding to the level of said received distinctively coded signals to automatically reset said switch means when said level is below a predetermined level.

9. The system of claim 1 further including means in the transmitter for automatically actuating the transmitter in response to operation of other emergency warning equipment on a vehicle.