'calculate doppler shifts
    c=186000*5280  'Speed of light in feet per sec
    nmfeet=6076
    fo=1.9e9  'frequency cell system
    print "Altitude in feet";: input alt
    print "horizontal offset in nm";:input Offset
    OffsetFt=Offset*nmfeet
    print "speed in knots";: input v
    print "initial x in nautical miles ";: input xi
    dt=1: 'delta t in seconds
    lprint "alt in feet = ";alt,"Offset in nm ="offset
    lprint "spd kts =";v,"   initial x in nm = ";xi
    lprint
    xi=xi*nmfeet
    fps=v*nmfeet/3600 ' velocity in feet per sec
    RangeOld=(alt^2+OffsetFt^2+xi^2)^.5
    lprint "  dist nm   SlantRange  dR/dt    Doppler"
    for t=0 to 50 step dt
       x=xi+fps*t
       SlantRange=(alt^2+OffsetFt^2+x^2)^.5 'in feet
       dr=SlantRange-RangeOld
       drdt=dr/dt 'slant range velocity in fps
       vr=drdt*3600/nmfeet 'slant range velocity in nm/sec
       Doppler = (drdt/c)*fo
       RangeOld=SlantRange
       lprint using "#####.##   "; x/nmfeet, SlantRange/nmfeet, vr, Doppler
    next t

    end