| 摘要 |
A device is provided for processing an echo received by an array of N receiving elements from a target at range R ensonified by an LFM signal of bandwidth B transmitted for a duration T. The device receives each elements output fn(t) over the elements total receiving time and selects time window element outputs f'n(t), which are discrete portions of fn(t), each time window extending from an arbitrary initial time T0 to time Tf and is spaced from T0 no more than T and, if there is a target within the window, an echo is received at time Tn. Further the device produces element frequency difference outputs gn(t) from the frequency difference between a replica of at least a portion of the transmitted LFM signal and the time window element outputs f'n(t), the outputs gn(t) being tones with frequencies directly proportional to the time Tn of the target from the time T0 so that the target range R=(c/2)(T0+Tn)+ DELTA Rn, where c is the speed of sound, and DELTA Rn is the distance by which R exceeds each element's range to the target. With this arrangement range and bearing of the target from the array can be more easily ascertained by dealing with parameters of cw, rather than broadband signals. This arrangement facilitates the application of adaptive beamforming techniques in a manner similar to their application to narrowband signals.
|
