| 摘要 |
<p>PURPOSE:To remove sea clutter automatically and effectively without suppressing echoes from a ship or the land unnecessarily, by providing a minimum value maintaining circuit between a statistic amount detecting circuit and a waveform correcting circuit. CONSTITUTION:An echo video signal (a) enters a statistic amount detecting circuit 12 from a terminal 1. An output is passed through a delay line 3 with taps each having a prescribed delay time, added up by an adder 4 and divided into 1/N by a divider 5, and thereby a statistic amount signal (mean value) (c) of the signal (a) in a time determined by the delay line is prepared. The signal (c) is put in a minimum value maintaining circuit 9 and an initial value is set in response to a transmission trigger signal (e) from a terminal 10. Thereby the minimum value of the signal (c) is maintained and a signal (d) is outputted. A signal (b) of the center tap of the delay line 3 is inputted to a subtracter or a divider 6 and subjected to waveform correction by the signal (d), and output (f) is inputted to a threshold value circuit 7 and subjected to subtraction by inputting a threshold value signal (g) from a terminal 8, thereby sea clutter is suppressed down to a receiver noise level, and an output is made from a video output terminal 2.</p> |
