Patent ID: 6032283
Filing Date: 2000-02-29
Classification: H03M

Abstract:
A method for correcting errors in a data frame including horizontal parity data enabling correction of errors in rows of the frame based on horizontal syndromes calculated on the rows, and vertical parity data enabling correction of errors in columns of the frame based on vertical syndromes calculated on the columns, the method including the steps of:calculating, on the fly, the horizontal and vertical syndromes of a current frame based on data of the current frame being received in a slow memory and storing these syndromes in a fast memory area; andas the data of a next frame are being received in the slow memory, finding values and positions of errors of the current frame based on the syndromes stored in the fast memory area,wherein the slow memory is managed by an exploiting circuit and the values and positions of the errors of each frame are supplied to the exploiting circuit among the data of the next frame, the exploiting circuit being adapted to store each frame and correct it upon reception of the values and positions of the corresponding errors;wherein the parity data constitute, with the remaining data, Reed-Solomon codes, each coefficient of a syndrome calculated on a row or a column of the frame being the value taken by a polynomial having coefficients constituted by the data of the row or column, for an element of a Galois field raised to a corresponding power, and wherein the vertical parity data are interlaced in the columns, the syndrome calculation including the steps of:setting a first auxiliary register to a predetermined element of the Galois field, raised to a power corresponding to the first datum of each column;setting a second auxiliary register to said element of the Galois field, raised to a power corresponding to the first vertical parity datum of the column;setting to 1 a variable register;updating the first auxiliary register with a product of its content and the inverse of said element of the Galois field upon each arrival of a new datum of the column, except upon arrival of a vertical parity datum;updating the second auxiliary register with a product of its content and the inverse of said element of the Galois field upon each arrival of a new vertical parity datum of the column;updating the variable register, for each syndrome coefficient, with a product of its content and the content of the second or first auxiliary register, according to whether the column datum currently received is or is not a vertical parity datum; andupdating, in the fast memory area, each vertical syndrome coefficient with a sum of the syndrome coefficient and of the product of the content of the variable register by the currently received datum.