Abstract: An audio signal is sampled, quantized and the values are stored in a specific digital data block/sub-block format on alternate tracks of a recording medium. The block/sub-block format provides an inherent simplification of error correction techniques, and consists of dividing the digital audio data into groups of digital words, and recording alternate words on separate tracks in the medium. Cyclic redundancy check characters, synchronization, and parity information are selectively interspersed with the data to define sub-blocks which in turn are combined into separate blocks of the block/sub-block arrangement. On reproduce, any errors, dropouts, etc., are detected and corrected or concealed to reconstitute the original audio signal. Editing is facilitated by the separated block arrangement which allows entering and exiting the record mode without destroying any data.

Abstract: A frequency equalization circuit includes an active filter circuit. The filter circuit differentiates the input signal. A plurality of adjustable resistances are connected to the differentiator corresponding to a plurality of operating or frequency ranges. A switch selects one resistance in accordance with one selected operating range to connect the filter circuit to an amplifier.

Abstract: A frequency equalization circuit includes an active filter circuit. The filter circuit differentiates the input signal. A plurality of adjustable resistances are connected to the differentiator corresponding to a plurality of operating or frequency ranges. A switch selects one resistance in accordance with one selected operating range to connect the filter circuit to an amplifier.