Emergency vehicle detection system

• US 6,778,101 B2
• Filed: 11/27/2002
• Issued: 08/17/2004
• Est. Priority Date: 11/30/2001
• Status: Expired due to Fees

• Current Assignee: John R. Majka, Terry A. Turbeville
• Original Assignee: John R. Majka, Terry A. Turbeville
• Inventors: Turbeville, Terry A., Majka, John R.
• Primary Examiner(s): Tweel, John
• Application Number:
  US10/305,496
• Publication Number:
  US 20030102985A1
• Time in Patent Office: 629 Days
• Field of Search: 340/902, 340/901, 340/904, 340/905, 455/59, 701/117
• US Class Current: 340/902
• CPC Class Codes: G08G 1/0965 responding to signals from another vehicle, e.g. emergency vehicle

Abstract

An Emergency Vehicle Detection System having a transmitter system for use in an emergency vehicle and a receiver system for use in a non-emergency vehicle. The transmitter system generates and transmits two distinct unmodulated continuous wave signals. The receiver system detects the presence and strength of the continuous wave signals, and produces DC voltage signals which are proportional to the strength of the received continuous wave signals. The DC voltage signals are used to generate a warning signal when both DC voltage signals reach a predetermined level for a predetermined amount of time (to prevent false alarms) and maintain the warning signal for a predetermined amount of time should one of the DC voltage signals fade (fading minimization). Additionally. DC voltage signals arc used to oscillate the warning signal at a rate which is proportional to the strength of the received continuous wave signals.

Claims

1. A system for emergency vehicle detection comprising:

a transmitter system for use in an emergency vehicle, said transmitter system having;

a first transmitter means for generating a first distinct unmodulated continuous wave signal;

a second transmitter means for generating a second distinct unmodulated continuous wave signal; and

a transmission antenna means for transmitting said first continuous wave signal and said second continuous wave signal, said transmission antenna means connected to said first transmitter subsystem and said second transmitter subsystem;

a receiver system for use in a non-emergency vehicle, said receiver system having;

a receiving antenna means for receiving said first continuous wave signal and said second continuous wave signal;

a first receiver means for detecting the presence and strength of said first continuous wave signal and for producing a first DC voltage signal which is proportional to said strength of said first received continuous wave signal, said first receiver means connected to said receiving antenna means;

a second receiver means for detecting the presence and strength of said second continuous wave signal and for producing a second DC voltage signal which is proportional to said strength of said second received continuous wave signal, said second receiver means connected to said receiving antenna means;

means for generating a warning signal when both first DC voltage signal and second DC voltage signal reach a predetermined signal level for a predetermined amount of time and for maintaining said warning signal for a predetermined amount of time should one of said DC voltage signals fade, said warning signal oscillating at a rate which is proportional to the signal strength of said second DC voltage signal.

2. The system of claim 1 wherein said transmitter means utilize a resonant parallel tank circuit to generate said corresponding continuous wave signal.

3. The system of claim 1 wherein said transmitter means utilize a crystal oscillator to generate said corresponding continuous wave signal.

4. The system of claim 1 wherein said transmission antenna means has a first transmitting antenna to which said first continuous wave signal is applied, and wherein said transmission antenna means further has a second transmitting antenna to which said second continuous wave signal is applied.

5. The system of claim 1 wherein said transmission antenna means has a diplexer circuit to which said first continuous wave signal and said second continuous wave signal are applied, and a diplexer antenna for transmitting said continuous wave signals, said diplexer antenna connected to said diplexer circuit.

6. The system of claim 1 wherein said receiver means utilize a Tuned Radio Frequency type receiver circuit.

7. The system of claim 6 wherein said receiver means further comprises a voltage doubler/RF detector followed by a voltage inverter, wherein said DC voltage signals are inversely proportional to said strength of said received continuous wave signals.

8. The system of claim 7 wherein said warning signal generating means further comprises enable logic means for generating an enable signal when both first DC voltage signal and second DC voltage signal reach said predetermined signal level.

9. The system of claim 8 wherein said enable logic means is a 7400N NAND gate, whereby said predetermined signal level is the level which causes the voltages on the inputs to said NAND gate to drop below 0.8 volts.

10. The system of claim 8 wherein said warning signal generating means further comprises fading minimization means for delaying said enable signal until said enable signal is present for said predetermined amount of time and for maintaining said enable signal until said enable signal is absent for said predetermined amount of time.

11. The system of claim 10 wherein said fading minimization means is a RC circuit with component values choosen such that a time constant for said RC circuit is substantially 0.5 seconds.

12. The system of claim 10 wherein said warning signal generating means further comprises a variable frequency oscillator means for generating an oscillating signal in proportion to said second DC voltage signal.

13. The system of claim 12 wherein said warning signal generating means further comprises a monostable oscillator for producing a constant frequency signal in the range of human perception for driving an audio/visual output, said monostable oscillator being enabled by said enable signal and said proportional oscillating signal, whereby said warning signal generating means produces a constant frequency signal which oscillates at a rate which is proportional to said second DC voltage signal.