| 摘要 |
A method and apparatus is disclosed for use of a linear frequency chirp in a transmitter/receiver (14/16) having a correlator to synthesize a narrow beamwidth pattern from otherwise broadbeam transducers when there is relative velocity between the transmitter/receiver (14/16) and the target. The chirp is so produced in a generator (20) in bandwidth, B, and time, T, as to produce a time-bandwidth product, TB, that is increased for a narrower angle. A replica of the chirp produced in a generator (26) is time delayed and Doppler shifted for use as a reference in receiver (16) for correlation of received chirps from targets. This reference is Doppler shifted to select targets preferentially, thereby to not only synthesize a narrow beam but also aim the beam in azimuth and elevation. |
