Abstract: A waveform shaping apparatus includes a shift register having a clock input terminal, data input terminals supplied with respective bits of a digital input signal and a plurality of data output terminals, and a plurality of coefficient multipliers connected to the respective data output terminals. A 2's-complement binary code offset within a predetermined range is used for representing the coefficient of each of the multipliers and such coefficient is controlled by manipulation of ON/OFF switches.

Abstract: A converted digital signal is provided in an NRZI (non-return to zero, inverted) code with a zero DC component and with a maximum predetermined number of bits between level transitions in the signal. The base digital signal is divided into m-bit base words, each of which is then converted into an n bit converted code word to form a converted digital signal suitable for recording. The n-bit converted code word is selected from a plurality of primary combinations or code words having a DC component substantially equal to zero when NRZI-coded and a plurality of secondary combinations or code words having a DC component with an absolute value of two when NRZI-coded. A variance of the DSV (digital sum variation) of each primary combination when NRZI-coded and a polarity of the DC component of each secondary combination when NRZI-coded are altered in response to the DSV at the exit of the preceding converted digital signal.

Abstract: A method for converting a digital data into an NRZI-coded digital signal is disclosed which is carried out by the steps of first detecting if the value of every even numbered bit of the digital data is digital zero, second detecting if two bits of the detected even numbered bits having digital zero value and a preceding odd numbered bit have a DC component, producing a detecting signal according to the result of the second detecting; and converting the digital data into the NRZI-coded digital signal by using the detecting signal.

Abstract: In the recording/reproducing of digital audio signals, errors are detected and corrected by using two parity words, one arranged at the center of the block formed of data words and the arranged at one end of the block. The probability that uncorrectable error will be present in the center of the block is relatively high, so placing the parity word there prevents loss of the more valuable data. Maximum correctable burst errors are determined by the length of the block, so placing the other parity word on the end of the block lengthens it and improves burst error correction. The parity words are arranged as indicated before adding a cyclic redundancy check (CRC) code to the data signal and then modulation coding the signal before recording. During playback, the reproduced signal is demodulated and the CRC code used to detect errors for which error pointers are generated.