process for converting linear coded pcm words into non-linear coded pcm words, and vice versa, non-linear coded pcm words into linear coded pcm words according to the a law gehorchenden 13 segment, characteristic curve

摘要

1. Method of converting linear-coded PCM-words into non-linear-coded PCM-words (companding) and vice versa for converting non-linear-coded PCM-words (linearisation), in accordance with a 13-segment curve which obeys the A-law, using a shift register into which, in the case of companding, a linear-coded PCM-word is input and is shifted until a significant bit appears at the shift register series output, whereupon, for the formation of the non-linear-coded PCM-word, the complement of the bit combination which characterises the number of shift clock pulses required for this purpose is used as higher-value word component, and a number of bits which follow the afore mentioned significant bit and which are contained in the shift register are used as lower value word component, and in the case of linearisation, the lower-value word component of a non-linear-coded PCM-word, which word component corresponds to the grading within the segments of the aforementioned curve, is input and shifted by a number of digits which is related to the relevant segment number of the curve, designated by that part of the non-linear-coded PCM-word which has not been taken into account, whereupon it is used, with the value which has been hereby changed, in order to form the higher-value part of the linear-coded PCM-word, characterised in that in the case of companding, the advance of the linear-coded PCM-word (L) which has been input into the shift register (SCH) and which is to be converted is prevented also when the aforementioned significant bit does not appear at the shift register series output but information shifts have taken place in a number which is 1 smaller than the highest segment number (7), and a counter (Z) which serves to count the shift clock pulses (t) and which is normally brought to a halt when the significant bit appears and whose count then indicates the complement of the number of the segment at which the converted PCM-word is located, is stepped on to its end count, and that in the case of linearisation, the lower-value portion (d, c, b, a) of a non-linear-coded PCM-word (K) which portion corresponds to the grading within a segment, prior to input into the shift register (SCH), is added to a specific bit combination if the PCM-word is assigned to the lowest-value segment (0) of the curve, and is added to another specific bit combination if it is assigned to a higher-value bit combination.