DISPOSITIF GENERATEUR DE FONCTION DE CONVOLUTION DISCRETE ET FILTRE NUMERIQUE INCORPORANT LEDIT DISPOSITIF

A digital filter is described which is based on the use of the so-called primitive roots transform and its inverse. This transform converts a series of binary numbers {an} into a transformed series WHERE G IS A PRIMITIVE ROOT OF A PRIME NUMBER P, AND THE VALUES BETWEEN SUPERFLUOUS PARENTHESES ARE TAKEN MODULO P. Said filter is provided with input means for applying fixed length data blocks made of a group of input samples appended with an equal number of zeros to the input of at least one circular convolutor. This convolutor is provided with accumulating means for generating multiples of each an term, adding means for generating said Ak terms by adding successively provided multiples of an to selected partial terms of Ak, and means for storing said partial Ak terms as they are formed. There is also a device for storing the Primitive Roots transform Bk of the set of filter coefficients appended with an equal number of zeros, a multiplier means for performing the operation Ck = Ak x Bk modulo p, and an invertor for inverting the resulting Ck bits. An inverse transformer having an accumulating means for generating multiples of the terms Ck, adding means for generating the terms of the inverse transforms cn by adding selected multiples of Ck and for storing said terms of said transforms is also provided. The filter also has an adding means for adding inverse transforms deriving from two consecutive blocks to generate a series of output terms representing a filtered signal.