| 摘要 |
<p>An antenna (26) projects a detection zone (28) across a road. A scanning receiver (32) couples to a computer (34). The receiver looks for one FM local oscillator (LO) signal (22) that may be emitted from within the detection zone. If one LO signal is detected, other LO signals that may be detected at the receiver are ignored until the one signal is no longer detectable (90-106). Detected LO signals are ignored if they are detected for less than a minimum duration (100) or if they are detected for greater than a maximum duration. The second of two consecutively detected LO signals is ignored if it occurs within a minimum duration from the previously detected LO signal and exhibits the same frequency as the previously detected LO signal.</p> |
