| 摘要 |
PURPOSE:To reduce remarkably the quantity of distance calculation for the soft decision of the most likelihood decoding by finding out a signal point existing in the region of the shortest distance, and applying the distance calculation between the signal point and a reception signal point. CONSTITUTION:A reception signal r0 outputted from an automatic equalizer 11 is inputted to a position deciding section 15, and a signal point closest thereto (reception signal deciding point Rn) is found out. A peripheral point vector generator 16' generates a vector between the deciding point Rn and each signal point existing at the region of the shortest distance including at least a signal point of each sub-set divided by convolution coding around the point Rn. A difference vector DELTArn between the reception signal point rn obtained by a subtractor 17 and the deciding point Rn is inputted to a distance calculation section 12', and when signal points rn are 13 points, a square Euclid distance between 13 vectors Pi and DELTArn is calculated, and the distance with a point closest to the reception signal point in each sub-set is used as a representative distance between the sub-set and the reception signal point, and the result is inputted to a Viterbi decoder 13. |
