| 摘要 |
A reading unit for reading data from a digital data carrier, the reading unit comprising a reading head including a sensor for sensing data from the data carrier and generating a sensor signal indicative for the sensed data, head positioning apparatus for positioning the head relative to the data carrier in response to a head positioning control signal; a head positioning controller for receiving the sensed data and being operable in accordance with a stored instruction set to process the sensed data to generate the head positioning control signal, and a data decoder for decoding the sensed data to form a digital output signal, the data decoder comprising a software section comprising a data processor operable to process data generated in response to the sensed data in accordance with a stored instruction set and a hardware section comprising dedicated hardware for performing at least one of the following: a digital phase locked loop for generating a clock signal for synchronisation of the decoder with the sensed data, an error checking unit for performing polynomial division; a cyclic redundancy check unit for analysing a data word to perform a cyclic redundancy check on it, a data packaging unit for packaging data bytes comprising a first number of bits so as to form data bytes having a second, less than number of bits, and a deinterleaving unit for deinterleaving a stream of data bytes.
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