| 摘要 |
PURPOSE:To attain cost reduction and simplify constitution by calibrating a signal in passive mode with the gain of a reception system which is measured in active mode, and detecting a target. CONSTITUTION:A reflected signal AA received by an antenna 4 and the high- frequency signal AN of a calibrating signal source 11 are supplied to a changeover switch 10 in active mode, and the signal AA when the distance is within a maximum distance range or signal AN when not is frequency-converted by a mixer 5 through a duplexer 3 and converted into a video signal AV by an amplitude detector 8, etc. Further, the signal AV is supplied to a gate circuit 12 to detect the target, and also passed through the 2nd smoothing circuit and the 2nd sample hold circuit 16, etc., and divided by the output of a comparative voltage source 18 at a dividing circuit 17 to output a gain signal GC. A radiation signal from the antenna 4 is converted into a signal AV through a detector 8, etc., in passive mode and this signal is passed through the 1st smoothing circuit 9 and multiplied by the signal GC at a multiplier 19.
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