| 摘要 |
A pulse-echo ranging system and method wherein transmit burst pulses are transmitted to a target at a first repetition frequency, an intermediate frequency signal is generated by sampling the received echo pulses from the target at a second repetition frequency slightly lower than the first repetition frequency, and the intermediate frequency signal is evaluated to determine the target distance. In order to compensate for phase error and thermal drift which may occur when the transmit and sampling instants are generated, the transmit burst pulses are periodically and alternately transmitted at the first and second repetition frequencies while the received echo pulses are simultaneously sampled at the second and first repetition frequencies, and the target distance is determined as half of the distance between echoes appearing in the intermediate frequency signal and resulting from the different clocks. |
