Abstract: Video compression is achieved by taking the Hadamard transform of video data, comparing Hadamard coefficients from consecutive lines, encoding the changed coefficient values via an entropy coding technique, removing superfluous bits and storing the data on a magnetic tape. The stored data can then be reproduced, unpacked and decoded to regenerate the original video data signals, thereby achieving a very high degree of compression with little or no degradation of image quality.

Abstract: A logarithmic delta modulated transmission system, comprising a logarithmic A/D converter (12) for outputting binary signals (16, 18) indicative of the polarity and size of the difference between an analog signal to be transmitted and a reconstructed signal (44), selection circuitry (22, 38) for sampling the polarity signal at a clock rate (20) and the size signals at a subharmonic (26, 34) of the clock rate, and outputting digital signals to be transmitted, and a logarithmic delta demodulator (42) for providing the reconstructed signal from the transmitted signals. The sizes of the difference are set to be logarithmic.

Abstract: Time-multiplex programmable switching apparatus for establishing on demand time shared connections between pairs of ports. Signals within the system are digital. The invention is described in the context of an electronic private automatic branch exchange (EPABX) telephone system. A central processor unit (CPU) including a recirculating memory carries port address pairs and digital information to be exchanged along with a status word used for identifying program loops. Program steps are sequenced or initiated by timing signals and signaling data from the port units. Common buses interconnect the port units with the central processor unit. Port units are grouped with a common buffer memory for converting parallel data from the CPU to serial form. The CPU memory includes slots for housekeeping functions to detect, inter alia, an off-hook telephone. The principles of the invention are applicable to telephone central offices and digital switching systems as for computers, for example.