Doppler radar

摘要

In the case of a Doppler radar having echo signals which are present in complex form in an I channel and a Q channel, a defined relative speed can be compensated for or simulated by presetting a value for a relative speed on the basis of its magnitude and, in the case of a pivoted antenna polar diagram, possibly in terms of direction as well, in that a clock generator produces a clock signal whose clock frequency is proportional to the predetermined relative speed and, in the case of an agile transmission frequency, to the product of the relative speed and the transmission frequency. An address counter which is incremented by the clock signal addresses two memories having sine and cosine function tables respectively. The echo signals are multiplied in a computation circuit in complex form by the sine and cosine values which have been read from the table. The output signals resulting from this exhibit a defined Doppler frequency shift from the input signals, which frequency shift is governed by the predetermined relative speed.