George A Jacoby, 91Kensington, NH

4337458, Jun 29, 1982

Feb 19, 1980

6/122632

Martin Cohn - Arlington MA
George V. Jacoby - Los Altos CA
Charles A. Bates - San Jose CA

Sperry Corporation - New York NY

H03K 1324

340347DD

A method and apparatus for encoding binary data in a data stream so as to increase the number of data bits represented by one transition, such as a transition recorded on a magnetic medium, and thereby increase the storage density. The data stream is converted into words each having m bits. Two of the data words are stored so as to be simultaneously accessible to a converting system that converts the data words into code words wherein each code word has n bits. In the invention, m/n=2/3. In order to increase the space between adjacent transitions, the conversion is carried out according to a scheme wherein all code words have at least one binary ONE and lack successive binary ONEs except certain cases in which a code word is converted to all ZEROs to avoid ONEs in the nth bit of a given code word and the first bit of the code word following the given code word. Also described is a decoding method and apparatus for recovering the encoded data and decoding it to the original binary data.

4081756, Mar 28, 1978

Dec 30, 1976

5/755875

Robert Price - Lexington MA
George V. Jacoby - Los Altos CA
Arthur P. Geffon - Sunnyvale CA

Sperry Rand Corporation - New York NY

H03K 520
H03K 5153

328117

A dual channel signal detector circuit comprising an equalizer for responding to a variable peak amplitude input signal, in which the peaks are representative of data, so as to provide a substantially constant peak amplitude output signal having discrete data representative pulses spaced along a base line, which is substantially flat at the zero level in regions intermediate the pulses, for application to separate peak detection and amplitude detection channels. The peak detection channel produces data pulses each indicative of the relative time occurrence of the peak of a respective data representative pulse while the amplitude detection channel is triggered by signal levels of the data representative pulses exceeding a predetermined threshold to produce gating pulses for gating the data pulses to the circuit output substantially exclusive of any noise that may be present at the input of the circuit.

4551773, Nov 5, 1985

Jul 16, 1982

6/398744

Martin Cohn - Arlington MA
George V. Jacoby - Los Altos CA
Jorgen P. Vinding - Monte Sereno CA

Sperry Corporation - New York NY

G11B 509

360 40

A ternary magnetic recording system wherein groups of binary input digits are transformed into corresponding groups of ternary recording code symbols utilizing a hierarchical code substitution system in which the longest valid group in the code is encoded. The code substitution system provides retention of the advantageous properties of a prior ternary recording system while significantly enhancing the automatic gain control utilized in amplitude discrimination between two of the ternary recording symbols. Anomalous detection of chained doublets is also obviated. Data recovery is effected by decoding apparatus utilizing an eight bit addressable ROM addressed with a twelve bit ternary word.