PROXIMITY WARNING TRANSMITTER FOR EMERGENCY VEHICLES

• US 3,660,811 A
• Filed: 11/12/1969
• Issued: 05/02/1972
• Est. Priority Date: 11/12/1969
• Status: Expired due to Term

• Current Assignee: Evelyn W. Vail, John Popik
• Original Assignee: Evelyn W. Vail, John Popik
• Inventors: Vail, Evelyn W., Popik, John
• Primary Examiner(s): Trafton, David L.
• Application Number:
  US04/875,668
• Time in Patent Office: 902 Days
• Field of Search: 340/32,33,34,384E 325/131,132 331/181 332/41
• US Class Current: 340/901
• 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
• CPC Class Codes: G08B 27/008 with transmission via TV or radio broadcast

Abstract

A transmitter, carried by an emergency vehicle, transmits directional jamming radiation to operating receivers of passenger vehicles in its path. Different fixed frequency audio signals alternately modulate both an AM carrier and an FM carrier to provide a wobbling sound at either AM or FM receivers. The carrier frequencies are varied through their respective broadcast bands to scan up and down their frequency spectrums so that the alarm is picked up by any receivers in the directional path of radiation regardless of the station to which it is turned. The carriers are caused to scan their broadcast spectrums by imparting reciprocating motion to slugs in inductor tuners in circuit with the respective oscillators, thereby varying the carrier frequencies.

Claims

1. A proximity warning transmitter to be carried by an emergency vehicle for transmission to conventional vehicle receivers comprising, in combination means for generating two conventional carriers of different frequencies;

means for modulating one of the conventional carriers with audio signals;

means for modulating the other of said conventional carriers with said audio signals but in a different fashion;

means for varying the frequency of each conventional carrier throughout a different band of frequencies; and

means for transmitting the modulated varying frequency carriers in a like predetermined direction relative to the emergency vehicle.

2. The proximity waRning transmitter of claim 1 wherein the means for modulating the conventional carriers comprises two separate sources of different frequency audio signals;

and switching means for alternately applying signals from said separate sources to modulate the conventional carriers and produce detectible audio warble carried by each.

3. The warning transmitter of claim 2 wherein the means for modulating said one conventional carrier comprises amplitude modulating means;

the means for modulating said other conventional carrier comprises frequency modulating means; and

said switching means comprises bi-stable multivibrator means.

4. The transmitter of claim 1 wherein the means for varying the frequency of said one conventional carrier throughout a band of frequencies comprises an inductor tuner in circuit with the means for generating said one conventional carrier, which inductor tuner exhibits inductance over the band of frequencies through which said one conventional carrier is varied;

a slug for said inductor tuner;

means for moving said slug relative to said inductor tuner to change the amount inserted therein, thereby changing the frequency of said one conventional carrier;

the means for varying the frequency of said other conventional carrier throughout a different band of frequencies comprises a second inductor tuner in circuit with the means for generating said other conventional carrier, which second inductor tuner exhibits inductance over the band of frequencies through which said second conventional carrier is varied;

a second slug for the second inductor tuner; and

means mechanically coupling said second slug to said means for moving the first mentioned slug to drive said second slug relative to said second inductor tuner to change the amount inserted therein;

thereby changing the frequency of said second conventional carrier.

5. The transmitter of claim 4 wherein the means for modulating the carriers comprises two separate sources of different frequency audio signals;

and bi-stable switching means for alternately applying signals from said separate sources to modulate the conventional carriers.

6. The transmitter of claim 5 wherein the means for moving said slugs comprises a reversible drive motor, stop limit switches, and power connections for the motor connected by the stop limit switches to reverse the motor drive, thereby to impart reciprocating motion to the slugs.