| 摘要 |
<p>A position detecting and control system for a vehicle including a low frequency transmitter and associated antenna with an associated fault indicating circuit, and a receiver and associated antenna with an associated fault responsive circuit. one of the antennas is mounted on the vehicle so the distance between the antenna carried by the vehicle and the other antenna is determined by the amplitude of the signal induced in the receiving antenna. The frequency of the transmitter is such that the distances to be monitored are a small fraction of the wavelength of the frequency involved, and any significant signal variations due to signal reflections which can reinforce or cancel the received signal are avoided. When the transmitter and receiving channels are operating properly the system monitors at least two different spacings between the transmitting and receiving antennas where the signals received at the receiving antenna are of widely different orders of magnitude. Separate range detecting circuits are coupled to a common point of the receiver, each of which includes an attenuator at the input thereof for adjusting the level of the signal to be fed to an associated signal level detector which operates a control device when the signal at the receiver output point involved reaches a level indicating the associated spacing to be monitored.</p> |
