AN EXCITER CIRCUIT FOR DIGITAL TELEVISION TRANSMITTERS

摘要

An exciter circuit for receiving input television digital signals from a source and converting the television digital signals into a standard format for broadcasting by television transmitter power amplification stages via an antenna, comprises a data recovery circuit for extra cting data and clock signals from the input television digital signal for outputting the extrac ted the digital clock signals for separately outputting the digital clock signals and the digital data signals, a randomiser circuit for altering the order of the extracted digital data signals in accordance with digital television standards, an encoder circuit for encoding the digital data s ignals into packets synchronised to receive the digital data signals at the input television digital signal rate, an interleaver circuit for performing a convolutional interleaving of the packets o f digital data signals synchronised to receive packets of digital data signals at a second laye r rate, an encoder circuit for encoding the convoluted interleaved digital data signals with a trel lis code according to digital television standards, a sync insertion circuit for inserting segment and field sync signal into the encoded digital data signals, a filter circuit for limiting the spectru m of the encoded digital data signals to the digital television standard, a signal insertion circ uit for inserting the extracted digital clock signal into the output of the filter circuit, a digital to analogue conversion circuit for converting the digital data signals and the digital clock signals in to analogue signals in form for transmission by the power amplifier stage, and a rate controler for receiving input signals and controlling output signals even in absence of the input signal.