| 摘要 |
PURPOSE: A matched pulse shaping filter is provided to generate a fully matched filtered signal compensated for distortion intrinsic to a received signal pulse shape and distortion introduced by a circuit element. CONSTITUTION: An input terminal(5) is coupled to an output terminal of a receiver front end. The receiver front end includes a source of an RF modulated HDTV signal, such as an antenna, an RF amplifier stage, an RF detector, and an IF amplifier stage. The receiver front end provides a near-baseband VSB(vestigial sideband) signal which includes successive symbol representative pulses having shapes exhibiting a square-root raised cosine filtered characteristic. The signal from the receiver front end also includes a pilot tone at a predetermined frequency. The input terminal is coupled to a cascaded connection of an analog-to-digital converter(202), a carrier tracking loop(204), a matched pulse shaping filter(214), a symbol timing loop(206), an equalizer(210), and a phase tracking loop(212). An output terminal of the symbol timing loop is further coupled to an input terminal of a synchronization detector(208). An output terminal of the synchronization detector is coupled to a clock input terminal of the equalizer and to other circuit elements in an HDTV system via an output terminal(25). An output terminal of the phase tracking loop is coupled to an output terminal(15). The output terminal is coupled to a receiver backend. The receiver backend includes a trellis decoder, a data deinterleaver, a Reed-Solomon decoder, a descrambler and circuitry for generating the image represented by the video component and the sound represented by the audio component of the HDTV signal.
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