Harmonic radar helps autos avoid collisions

Abstract

In the foreseeable future, a radar system immune to clutter through use of a special reflecting tag could aid the the driver to maintain a safe distance between the cars, the closing rate, and the driver's ground speed. To eliminate the clutter and blinding problems, a system has been designed that uses an harmonic radar concept. An experimental harmonic radar collision avoidance system has been built using an RCA transferred electron oscillator power source. The measurement of distance was quite repeatable and of adequate accuracy for highway use. In the automatic braking system once the alarm is given, the brake pedal is automatically depressed by a force that increases linearly with time up to maximum pressure until the alarm is removed. The force is then removed linearly with time. The harmonic radar system will reject all blinding signals that it receives other than the second harmonic of its transmitted frequency. The possibility of a false alarm from crosstalk interference is reduced with harmonic radar. The system is adaptable to integrated and printed-circuit techniques. It operates in regions of the frequency spectrum which are still underutilized and spectrum space can be set aside for its future use. The average power density in the immediate vicinity of the antenna is 0.2 mW/cm2. When a dangerous driving situation is detected, an audible warning is sounded and a warning light is flashed. The harmonic radar system provides protection from certain types of rear-end collisions; those where the car in front is in line with the following car. Vehicles that are stopped, but not parallel to the center line, will not be seen by the following car because of the purposefully narrow beam of the passive reflector./SRIS/