Data error correcting method for digital signal frames and apparatus used in the method

A data error correcting apparatus for digital signal frames, comprising:

• a data input unit for receiving data which constitutes one frame with m blocks each consisting of n bits and which requires error correction;
• a data holding unit for receiving the data in units of blocks from said data input unit;
• a frame buffer capable of storing the data constituting one frame;
• an error correcting unit capable of receiving the n- or m-bit data from said data input unit or said frame buffer, performing error correction for the data, and outputting the error-corrected data and a determination signal indicating whether the error correction is normally performed;
• and
• a selector for supplying the error-corrected data to said frame buffer if the determination signal indicates that the error correction is normally performed, and supplying the data held in said data holding unit if the determination signal indicates that the error correction is not normally performed,
• wherein the data requiring error correction is sequentially supplied in units of blocks from said data input unit to said data holding unit and said error correcting unit, first error correction is performed for the data received in units of blocks by said error correcting unit, if the error correction is normally performed, output error-corrected data from said error correcting unit is stored in said frame buffer, if the error correction is not normally performed, data before error correction held in said data holding unit is stored in said frame buffer, after the first error correction is completely performed for the m blocks, combinations of corresponding bits are sequentially supplied from each block of the m-block data stored in said frame buffer to said error correcting unit, second error correction is performed for each of the bit combinations, the error-corrected bit combinations are returned to said frame buffer, after the second error correction is completely performed for the n bit combinations, the m-block data stored in said frame buffer is sequentially applied in units of blocks to said error correcting unit, third error correction is performed for the data in units of blocks, the error-corrected data is returned to said frame buffer, and the data subjected to the third error correction is output.

A data error correcting system comprising:

• a data input unit for receiving data requiring error correction and outputting n bits as one block;
• an error correcting unit for receiving data in units of blocks, performing error detection/correction processing for the input data, outputting the corrected block data if the data correction processing is possible, and outputting the uncorrected block data if the data correction processing is impossible;
• and
• a frame buffer for receiving the output block data from said error correcting unit and storing only n blocks,
• wherein bit data from each of the n blocks stored in said frame buffer is applied as one block to said error correcting unit and again subjected to error correction processing, the data again subjected to error correction processing is sequentially read out in units of blocks and transferred to said error correcting unit, and third error correction processing is performed for the data,
• further comprising:
• a block data holding unit for receiving and holding data output in units of blocks from said data input unit;
• and
• a selector for selecting one of the block data held in said block data holding unit and the output error-corrected block data from said error correcting unit in accordance with an error signal, said selector outputting the block data from said block data holding unit if the error signal is present and outputting the error-corrected block data from said error correcting unit if the error signal is not present.