Abstract: A multi-chip module is composed of two or more integrated-circuit chips located on a substrate such as a dielectrically coated silicon substrate. The chips are interconnected by means of transmission wiring lines. At least some of the chips contain one or more input buffer circuits, each composed of two branches ("legs"). Each such branch contains, in one embodiment, an n-channel MOS transistor connected in series with a pair of series-connected p-channel MOS transistors--whereby, in each such branch, one of the p-channel MOS transistors is located between (intermediate) the other of the p-channel MOS transistors and the n-channel MOS transistor of that same branch. On the other hand, in each buffer circuit, the intermediate p-channel MOS transistors of both branches are cross-coupled.

Abstract: An apparatus provides digital data representative of a compressed high definition video image signal in a manner such that a conventional video tape recorder (VTR) employing current electrical and mechanical technologies is adaptable for reading this data for display in special modes such as fast forward, reverse and still frame. To minimize the loss of data while the VTR is operating in one of these special modes, the data representative of the high definition image signal is decoded by the apparatus to yield available time slots in the data stream. These time slots are then filled with data which duplicates the most important of the original transmitted data then existing in other time slots in the data stream. This duplicating of the data increases the likelihood that the important picture information will be read by the VTR while operating in a special mode.

Abstract: An improved predictive encoder where the leak signal is a function of the buffer fullness of the encoder. More specifically, the signals stored in the encoder output buffer are further encoded based on the fullness of the buffer, and information about this further encoding is used in determining the leak factor level. In accordance with another improvement, this leak factor level is not constrained to granularity that is imposed by the decoder hardware. Removal of the constraint is accomplished by cycling through a sequence of permissible leak levels that averages at the desired level.

Abstract: Effective control of impedance values in integrated circuit applications is achieved with an integrated circuit transistor whose size is digitally controlled. The digitally controlled size is achieved, for example, with a parallel interconnection of MOS transistors. In one application, the digitally controlled transistor serves as a controlled impedance connected to an output terminal of an integrated circuit. In that application, a number of transistors are enabled with control signals, and the collection of enabled transistors is responsive to the input signal that normally is applied to a conventional transistor. In another application, where the digitally controlled transistor serves as a controlled impedance at the input of a circuit, only the control signals that enable transistors and thereby determine the effective developed impedance are employed.

Abstract: Blocks of HDTV picture information are selected for transmission at a plurality of channel rates of an HDTV transmitter. The size of each block of HDTV picture information is dependent on a target distortion parameter for the HDTV picture information. As a result of this selection, a portion of each block of HDTV picture information is transmitted at the lower channel rate, with the result that the HDTV transmitter range is maximized while maintaining a picture quality for the resulting HDTV video image.

Abstract: Effective control of impedance values in integrated circuit applications is achieved with an integrated circuit transistor whose size is digitally controlled. The digitally controlled size is achieved, for example, with a parallel interconnection of MOS transistors. In one application, the digitally controlled transistor serves as a controlled impedance connected to an output terminal of an integrated circuit. In that application, a number of transistors are enabled with control signals, and the collection of enabled transistors is responsive to the input signal that normally is applied to a conventional transistor. In another application, where the digitally controlled transistor serves as a controlled impedance at the input of a circuit, only the control signals that enable transistors and thereby determine the effective developed impedance are employed.

Abstract: Effective control of impedance values in integrated circuit applications is achieved with an integrated circuit transistor whose size is digitally controlled. The digitally controlled size is achieved, for example, with a parallel interconnection of MOS transistors. In one application, the digitally controlled transitor serves as a controlled impedance connected to an output terminal of an integrated circuit. In that application, a number of transistors are enabled with control signals, and the collection of enabled transistors is responsive to the input signal that normally is applied to a conventional transistor. In another application, where the digitally controlled transistor serves as a controlled impedance at the input of a circuit, only the control signals that enable transistors and thereby determine the effective developed impedance are employed.

Abstract: A high definition television system that is characterized by low transmission bandwidth is achieved by removing redundancies in the signal, encoding the remaining signals, and transmitting the encoded signal in a manner that is most compatible with the applicable standards. The dynamic range of the encoded signal is reduced by combining groups of adjacent samples that are smaller than a "floor" threshold to form larger samples, and by splitting samples that are larger than a "ceiling" threshold to form a plurality of smaller samples. Encoding of the combined samples is carried out in a conforming manner to minimize deleterious effects of transmission noise.

Abstract: A motion compensated encoder where motion vectors are selected based on the prediction error generated in localized areas of the encoded image and based on an available bit budget. The motion vectors are created by dividing the image into blocks of two sizes and by considering the best mix of large and small size blocks, and their associated motion vectors, that minimize the overall prediction error, within the constraints of the bit budget. For convenience, the image division is arranged so that a given number of small sized blocks forms one large sized block (e.g. 16:1). Also, the block sizes are arranged so that employing only large sized blocks does not exceed the given bit budget, while employing only the small sized blocks does exceed the given bit budget.

Abstract: An arrangement for a television receiver to attenuate correlated noise injected by the transmission medium. Recognizing that there is substantial line to line correlation of the transmission noise injected by interfering television stations, this arrangement enhances noise immunity by inserting in the receiver a de-emphasis stage that includes a circuit for removing the correlated noise. To account for the modifications to the desired signal that are introduced by the de-emphasis circuit, a pre-emphasis circuit is included in the transmitter. In accordance with one embodiment, the receiver's circuit comprises a feed-forward arrangement where the received signal of a scan line is subtracted from a fraction of the received signal of the previous scan line. At the transmitter, a feedback loop develop a scan line to be transmitted that corresponds to a video scan line subtracted from a fraction of the previous scan line to be transmitted.

Abstract: A quantizer, with quantization control that is sensitive to input signal characteristics and to output buffer fullness responds to an input signal that is divided into blocks and DCT transformed. The transformed signal is analyzed to develop a brightness correction and to evaluate the texture of the image and the change in texture in the image. Based on these, and in concert with the human visual perception model, perception threshold signals are created for each subband of the transformed signal. Concurrently, scale factors for each subband of the transformed signal are computed, and a measure of variability in the transformed input signal is calculated. A measure of the fullness of the buffer to which the quantizer sends its encoded results is obtained, and that measure is combined with the calculated signal variability to develop a correction signal. The correction signal modifies the perception threshold signals to develop threshold control signals that are applied to the quantizer.

Abstract: An HDTV receiver design includes a reconstruction section and an inner loop section. The reconstruction section comprises a receiving section for accepting the television receiver's antenna signals, for separating out the component signals from the received signals and for decoding the separated signals. The decoded signals are applied to a quantization decoder that is responsive to vector codebook and to applied quantized vector signals, and the output signals of the quantization decoder are applied to an inverse DCT circuit. The inner loop comprises an adder for adding an estimate signal to the output of the DCT circuit, a frame buffer, a motion compensation circuit that is capable of translating large blocks as well as small blocks and a leak circuit that modulates the output of the motion compensator circuit in accordance with a received leak control signal.

Abstract: In a differential PCM encoder, the problem of error perpetuation is solved by leaking a changing, rather than a fixed, fraction of the input signal to the differential PCM. The fraction leaked is sensitive to the characteristics of the signal. In one embodiment the fraction leaked is fixed for a frame in accordance with a chosen characteristic of the frame signal. In another embodiment, the fraction leaked is set in accordance with one function when a chosen characteristic of the frame signal exceeds a given level, and follows another function when the chosen characteristic does not exceed the chosen level. In a still another embodiment, the fraction leaked is set to one of two levels, based on a chosen characteristic of the frame signal.

Abstract: A programmable memory system that interfaces with a computer's control and data manipulation units, and is capable of performing the manipulation, bookkeeping, and checking that would normally be performed by the computer. The memory system comprises active structure modules that are interconnected in a network to form clusters. The clusters are interconnected to form an aggregate memory system. Each ASE contains a processor section and a conventional memory section.

Abstract: Graceful degradation for digitally encoded HDTV signals is achieved by appropriately coding the image to provide a controllable degradation of chosen image characteristics, such as temporal degradation, spatial degradation, and dynamic range degradation. In the temporal degradation approach of this invention, the resolution of movement suffers when noise is introduced. In the spatial degradation approach, the spatial resolution of the image is sacrificed. In the range degradation approach, the dynamic range of the signals is sacrificed. The graceful degradation is achieved by dividing the transmitted signal into two or more parts, such as parts A, B and C. Part A is given the heaviest error-correcting code; part B is given a "medium" error correcting code; and part C the is given the least powerful error correcting code (or perhaps none at all). A receiver that is close to the transmitter most likely receives parts A, B and C.

Abstract: A high definition television system that is characterized by low transmission bandwidth is achieved by removing much of the redundancies in the signal, efficiently encoding the remaining signals, and transmitting the encoded signal in a manner that is most compatible with the applicable standards. To enhance noise immunity a number of techniques are employed. One is to encode adjacent low-amplitude signals into larger signal samples, another one is the introduction of a controllable gain feature, a third one is the introduction of both fixed and variable leak, and still another one is the incorporation of signal scrambling.

Abstract: A high definition television system that is characterized by low transmission bandwidth is achieved by removing redundancies in the signal, encoding the remaining signals, and transmitting the encoded signal in a manner that is most compatible with the applicable standards. In the encoding, groups of signals to be sent are mapped to codebook vectors and the identities of the codebook vectors are sent together with those signals of the groups of signals that correspond to the codebook vectors. To insure that the total number of signals that are sent does not exceed the available capacity, the signals are sorted by a selected importance parameter and assigned for transmission in descending order of importance until the capacity is exhausted. Signals that are not assigned for transmission are discarded.

Abstract: A high definition television system that is characterized by low transmission bandwidth is achieved by in a manner removing much of the redundancies in the signal, efficiently encoding the remaining signals, and transmitting the encoded signal in a manner that is most compatible with the applicable standards. Specifically, the television signal is encoded by developing motion vectors that describe the best motion estimate of the image to be transmitted, by developing motion estimation error signals, by encoding these error signals within the same bandwidth as occupied by standard NTSC signals and by transmitting the encoded error signals during periods that correspond to the active scan intervals of the NTSC TV signal. The motion vectors themselves, together with video and control signals, are transmitted during the NTSC retrace period.

Abstract: A high definition television system that is characterized by low transmission bandwidth is achieved by removing redundancies in the signal and encoding the remaining signals. In the encoding, a portion of the signals to be transmitted is created in the form of an analog signal or a concatenated plurality of pulse amplitude coded samples (A-signal), and another portion of the signals to be transmitted is created in digital form (D-signal). The D-signal is consigned to a specified portion of the transmitted signal, leaving the remainder of the transmission capacity for the A-signal. When the normally created digital signals do not fully occupy the digital portion, enhanced operation results when selected ones of the analog signals or samples are excised from the A-signal, encoded digitally, and added to the D-signal. The excising of those signals leaves room in A-signal portion to include additional analog signals. This leads to an overall better image reproduction at the receiver.

Abstract: A packet switching network that accommodates the appearance of multiple occurrences of packets addressed to the same destination are accommodated. The network includes a recirculating delay block within the switch, and an expander that includes a modest number of multiple appearances of the same address, followed by memories that accept the packets delivered at those multiple appearances, store the packets, and output the stored packets to the user, one at a time, in accordance with a set priority scheme.