Abstract: A traffic information warning system for conveying first and second messages regarding a traffic situation from a traffic advisory site is disclosed. The system comprises a transmitter adapted for placement at the advisory site and a receiver. The transmitter includes an oscillator for transmitting a first carrier signal and a second carrier signal. The first carrier signal has a first discrete carrier frequency and the second carrier signal has a second discrete carrier frequency. The first and second discrete carrier signal frequencies are located at a frequency location. The first message of a traffic situation is reflective of the specific frequency locations of the first and second discrete frequencies. A modulator modulates the first carrier signal with a modulating signal reflective of the second message regarding the traffic situation. The second carrier signal comprises an unmodulated signal.

Abstract: A combined motion detector/transmitter device for a traffic information warning system is disclosed. The device includes first and second oscillators for transmitting first and second carrier signals, respectively. The first carrier signal has a first carrier signal frequency and the second carrier signal has a second carrier signal frequency. The carrier signals are used to transmit a message regarding a traffic situation based upon either the magnitude of the frequency difference between the first and second carrier signal frequencies or the specific frequency locations of the carrier signals. The first and second oscillators also set up first and second disturbance fields, respectively. A first reflected signal receiver is associated with the first oscillator and receives a first reflected signal when a target is within the first disturbance field.

Abstract: A traffic information warning system for conveying traffic information from a traffic advisory site to a vehicle is disclosed. The traffic warning site comprises an emergency vehicle, a roadside hazard, or the like. The system comprises a transmitter adapted for placement at the advisory site and a receiver adapted for placement at the vehicle. The transmitter includes a first oscillator for transmitting a first carrier signal having a first carrier frequency and a second oscillator for transmitting a second carrier signal having a second carrier frequency. The first carrier frequency and the second carrier frequency are spaced apart by a predetermined frequency difference. The transmitter also includes a modulator for modulating both carrier signals with an identical modulating signal reflective of a traffic situation.