摘要 |
Measurement of distance is carried out by transmitting a VHF wave train comprising a sinusoidal signal modulated by phase inversion in accordance with a pseudo-random sequence, at a receiver shifting a like second sequence until it coincides with the received sequence, re-transmitting a signal modulated by the second sequence, receiving the second sequence and shifting a like third sequence until it coincides with the received second sequence, and measuring the phase shift between the third sequence and a like reference sequence. |