| 摘要 |
PCT No. PCT/DE96/01675 Sec. 371 Date Mar. 9, 1998 Sec. 102(e) Date Mar. 9, 1998 PCT Filed Sep. 6, 1996 PCT Pub. No. WO97/09638 PCT Pub. Date Mar. 13, 1997A signal source produces a frequency-modulated signal. The signal is supplied to a transmit/receive unit and transmitted. A surface-wave element produces a signal delayed by a delay from the frequency-modulated signal. A mixer mixes the delayed signal with the received signal and outputs the mixed signal to an evaluation device. The delay is preferably equal to the propagation time of a signal on the measurement path. The coherence length of the ranging apparatus is thereby substantially improved. |
