| 摘要 |
<p>Radar detection and signal processing circuits having an RF and local oscillator mixer (16), an I.F. (18), a swept frequency oscillator (24), and a band pass filter (30) whose output goes to a detector (34) for frequency modulated intermediate frequency signals. The detector has at least a first output signal that is fed to two pairs of complementary paired comparators (48, 48; 50, 50), the outputs of which are set to low and high threshold levels. The output of the first pair of complementary comparators (48, 48) is examined by a microprocessor (42) for the incidence of detected low threshold signal in a number of spaced cells -- as determined by a clock which divides the detector output into time cells of the sweep period of the swept oscillator. Signal processing is provided so that the incidence of signals in a pair of spaced cells over a given number of consecutive sweeps causes an alarm. Likewise, a high threshold output is examined so that the incidence of a detected high threshold signal in a pair of spaced cells over a different, lower number of consecutive sweeps, causes an alarm. The sensitivity of the circuit may adjust up or down according to the number of low threshold signals that are detected.</p> |
