Empfangseinrichtung in einer Radaranlage

Multilevel Digital Skimmer

... 1,156,896. AID converters. HUGHES AIRCRAFT CO. 15 Feb., 1968 [23 Feb., 1967], No. 7559/68. Heading G4H. [Also in Division H4] In a radar receiving system the peak level of video returns is detected during each range bin, the receiver gain is determined at selected instants to afford a reference voltage related to the receiver gain and detectors are each responsive to the peak magnitude, the reference voltage and an adjustable threshold (" skim ") level, each detector providing an output signal when the peak video level exceeds the skim level by a preselected magnitude which is different for each detector. In the embodiment the receiver is logarithmic and the skim level is set by known means to maintain a constant false alarm rate related to " hits " 3dB above R.M.S. noise. The peak video level detector is a box-car and the detectors D2 . . . D7 include resistors R2 ... R7, operational amplifiers 30, inverters 33 and bi-stables 32. The outputs of detector D2 . . . D7 may be applied to a ...