| 摘要 |
PURPOSE:To change only an initial value to generate fixed range markers having intervals of an optional length without increasing the number of elements, by using an up/down counter provided with an initial value setting circuit. CONSTITUTION:When the cycle of a reference clock signal 9 of a reference clock generating circuit 1 is denoted as ts and a time corresponding to a length of intervals of markers is denoted as tm, a value N which makes tm=tsXN true is set as the initial value. The initial value N is counted down synchronously with a radar trigger signal 16 by the reference clock signal 9, and a borrow signal is used as a clock signal 14 for display, and the initial value is loaded again at the generation time of this clock signal 14, and this counting-down is repeated by the reference clock signal 9. The clock signal 14 for display is mixed with a sweep video signal 17 and a radar video signal 18 in a video amplifiers 7 to become a composite video signal 15, and fixed range markers appear on the sweep. Since an up/down counter is used instead of an n-notation counter, fixed range markers having intervals of an optional length are attained easily only with the change of the initial value of the counter, and it is unnecessary to increase the number of elements or wirings. |
