| 摘要 |
PURPOSE:To determine the time upto the arrival of an object approaching at a constant speed with a simple construction by measuring the variation rate in the level of receiving radio waves emitted from a moving object. CONSTITUTION:A wide dynamic receiving circuit 1 receives and transmits radio waves emitted from a moving object to a memory circuit 3 via an analog-digital convertion circuit 2. At the same time, a timing signal is sent to the circuit 3 from a timing circuit 4 to memorize a receiving level and then, a certain time later, a timing signal is sent to a level variation rate computing circuit 50 to fetch the current signal level. The signal level memorized in the circuit 3 is read out to determine the corresponding DELTAPdB. This DELTAPdB precisely corresponds to the time up to the arrival of the moving object and thus, the time up to the arrival thereof is calculated by a specified computation with a time calculation circuit 6. |
