| 摘要 |
<p>A vehicle position indicator system utilizing microwave detection of nearby vehicles is disclosed. The system includes two slot receiver antennas formed in the longitudinal extremities of a bumper of a vehicle and a slot transmitter antenna formed in the bumper between the two slot receiver antennas. The slot transmitter antenna is driven by an amplitude modulated signal, and the slot receiver antennas drive respective direct conversion receiving circuits. Since, each slot receiver antenna drives one of two identical receiver circuits, the approach direction of another vehicle can be detected and displayed to the driver. Each receiver circuit includes a mixer for mixing the received amplitude modulated microwave signal with a locally generated microwave signal, thus for detecting the modulated signal. Each mixer is followed by an audio amplifier and active filter for passing only the modulated signal. The active filter outputs drive respective Schmitt triggers which in turn drive respective indicators to indicate that the other vehicle is approaching the rear of the vehicle from either the left or right. A summation circuit is driven by both receiving circuits such that when both receiving circuits are receiving reflected signals, an indicator is activated to indicate that the other vehicle is approaching the center of the vehicle.</p> |
