A system for decoding coded data printed in ink on a surface. The coded data includes an encoded bit stream and associated redundancy data, and a registration structure of clock tracks indicative of a position of the coded data in the direction perpendicular to an alignment direction and two alignment lines for each clock track. The system has a store for storing the coded data and a decoder for determining a codeword format for the coded data, reading the coded data from the store using the determined format, correcting errors in the encoded bit stream, and writing the corrected data to the store. The coded data is read so as to de-interleave the encoded bit stream and redundancy data into codewords. The decoder uses an alignment phase-locked loop (PLL) to determine a position of the alignment lines so as to determine the position of each respective track and update the alignment PLL.