| 摘要 |
PURPOSE:To measure the speed of a vehicle and limit measured vehicles to vehicles within a certain distance from an antenna by modulating a transmission wave. CONSTITUTION:A carrier from a microwave generator 1 is modulated in a microwave switch 3 by output pulses from a pulse generator 2. The turned-on/off transmission wave is radiated from an antenna 6 through a circulator 5. Radio waves reflected on a vehicle 9 are received by the antenna 6 and are inputted to a mixer 10 through the circulator 5. Frequency mixed detection of the received wave and the injected wave is performed by this mixer, and the output is given to a frequency counter 12 through an envelope detector 11. A differential frequency between the received wave and the injected wave is counted by the frequency counter 12 to detect the speed of the vehicle. |
