| 摘要 |
<p>PURPOSE:To detect a moving target alone such as airplane accurately, by employing only one FIR filter using a selected filter coefficient to remove a clutter having a Doppler speed such as rain clutter efficiently. CONSTITUTION:A pulse pair type circuit which comprises a sweep memory 2, a complex type multiplier 3, a bearing average circuit 4 and a tan<-1> table 5 determine a Doppler velocity of rain clutters. A distance averaging circuit 7 averages Doppler velocity distance-wise to ensure that the Doppler velocity of a moving target is not outputted from an output of the circuit 7 even if the Doppler speed of a moving target such as airplane or the like is obtained. A coefficient table 8 contains coefficients that could remove frequency components of rain clutters. Time response is so set that a band reject filter is given in a frequency area, a filter coefficient is selected corresponding to the Doppler velocity of the rain clutters. Thus, sweep memories 9-11, complex multipliers 12-14 and an adder 15 composing an FIR filter acts as filter to remove rain clutters.</p> |
