| 摘要 |
A receiver employs fast-Fourier-transform modules to process the received signals in the frequency domain. It samples the input signal at a high sampling rate to cover a broad input bandwidth, but it transforms the sampled input signals in short segments, segments that cover time durations considerably shorter than the duration of the impulse response of the receiver's tuner filter. The transform of the sampled input signal is multiplied by a Gaussian transfer function to reduce the amount of information contained in the signal, and the values of the resultant frequency-domain sequence are reordered in such a manner as to correspond to resampling in the time domain at a slower rate. This results in coverage of the time duration of an input segment by a relatively small number of samples. The results of several input segments are concatenated to generate a filtered time-domain sequence that covers a real-time period long enough to provide an adequate tuner-filter signal history but consists of relatively few points and so requires only a short time for Fourier transformation. This longer-duration signal is transformed back to the frequency domain, where it is multiplied by the receiver transfer function and then inverse transformed to produce the receiver output.
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