19. The detecting data processing apparatus as claimed in claim 17 , wherein each of the code words is generated from a seed, seeds for each possible code word of the code words being stored in a data store, the code word re-generator being arranged to generate the code words in accordance with keys, the plurality of code word coefficients being pseudo-random numbers.
19. The detecting data processing apparatus as claimed in claim 17 , wherein each of the code words is generated from a seed, seeds for each possible code word of the code words being stored in a data store, the code word re-generator being arranged to generate the code words in accordance with keys, the plurality of code word coefficients being pseudo-random numbers. 20. The detecting data processing apparatus as claimed in claim 19 , wherein information representing a structure of the at least one data word is stored in the data store for access by the control processor, the structure providing a number of the at least two fields in the at least one data word and a number of digits in each of the at least two fields.