Simulated digital radar system with earth curvature and atmospheric effects

DETAILED DESCRIPTION I claim: 1.
An earth curvature correction circuit adapted for use in a digital radar landmass system for accumulatively decreasing the terrain elevation of each range point thereof to simulate the effect of the earth's curvature, comprising: a range point counter having an output which increases during each sweep line and which remains proportional to the current range point; a curvature control having an output proportional to the desired radius curvature; a multiplier which forms the product of the range output of the counter and the curvature output of the control; an adder which forms the sum for each range point of the multipler product plus the multiplier product for the previous range point; and output register for temporarily holding the sum for each range point for outputting and for returning each sum to the adder to be added to the next range point product to form the next range point sum.
2.
The circuit of claim 1, wherein: the output of the range point counter is n and increases for each range point; the output of the curvature control is a constant K; the output of the multiplier is Kxn; the output of the adder is Kxn + EC.
sub.
n-1 where EC.
sub.
n-1 is the earth curvature correction output of the previous range point n-1; and the output of the output register is EC.
sub.
n = K(n.
sup.
2 + n).
3.
The circuit of claim 2, wherein the curvature control constant K represents the curvature of the earth and atmospheric effects.
4.
The circuit of claim 2, wherein the curvature control constant K represents only the curvature of the earth.
5.
The circuit of claim 2, wherein K may be increased or decreased.




Description:
FIELD OF INVENTION This invention relates to a an earth curvature subsystem for simulated digital radar system.
SUMMARY OF THE INVENTION It is, therefore, an object of this invention to provide earth curvature and atmospheric effects for a simulated digital radar system.
BRIEF DESCRIPTION OF THE FIGURES Further objects and advantages of the present invention will become apparent from the following detailed description taken in conjunction with the drawings in which: FIG