Abstract: A projection television system includes an automatic contrast control section for controlling the amplitude of the luminance signal in response to the peak value of a luminance-representative image component signal in order to prevent white-spot blooming. Circuitry is provided for deactivating the automatic contrast control section when a user sets the contrast control level above a given threshold level, e.g., corresponding to the maximum contrast control level. As a result white-spot blooming is inhibited in order to ensure sharp images for a contrast control range below the given threshold level while allowing maximum white image components to be produced (at the expense of white spot blooming) when the contrast control level is set above the threshold level, depending on the preference of the user.

Abstract: An MPEG compatible decoder receives encoded, compressed data in the form of image representative pixel blocks. The decoder includes a frame memory (20) for storing reconstructed pixel blocks incident to the decoding process. The previously decompressed data is re-compressed (30) before being written to the memory. Stored decompressed data is decompressed for display (34, 26), or as needed for decoding functions such as motion compensation processing (32, 22). The compression performed before writing data to memory is block-based compression using compressed data from one of two different compression paths (FIG. 3, 314, 320) which compress a given pixel block simultaneously.

Abstract: Program specific information (PSI) is formed suitable for use in recovering data content of a program in the form of a packetized datastream. Packet identifiers (PIDs) that identify individual packetized datastreams constituting the program are renumbered and corresponding packetized datastreams that constitute different programs are given the same PID. A program map table (PMT) is created that associates the renumbered PIDs with the individual packetized datastreams constituting the program. A program association table (PAT) is also created for associating the program with PIDs that identify packets comprising the PMT. A parameter may be employed within the PSI to indicate that the PSI is to be applied in subsequent processing of the program irrespective of a substantive difference between the PSI and previous PSI content. In addition, the PSI may incorporate a version number that is varied between successive occurrences of the PSI irrespective of substantive change in PSI content.

Abstract: A decoding method minimizes the use of incorrect program specific information (PSI) parameters across program boundaries and provides default video and audio outputs for reproduction during error conditions. Program representative packetized datastreams incorporating PSI suitable for use in recovering data content of the program are decoded. PSI packets in the datastream are identified and a parameter within the identified PSI data is used to determine whether the identified PSI data is to be used for decoding the program content, irrespective of previous PSI content. Current PSI is updated with the identified PSI data in response to the parameter. Program content packets are identified using the current PSI. The program content packets are assembled into a decoded datastream using the current PSI. The current PSI may also updated with the identified PSI data irrespective of the content of the identified PSI data, provided that there is an absence of a PSI content error indication.

Abstract: A television receiver includes an MPEG decoder for providing decoded pixel blocks. Decoded pixels are recompressed prior to storage in frame memory. In the recompression process a reference first pixel is compressed as a function of a pixel block parameter. A reconstructed reference pixel value is used in a prediction network when reconstructing remaining pixels of the pixel block prior to display. A first pixel processor accurately compresses a reference pixel which prevents the propagation of a prediction error throughout the reconstructed block.

Abstract: A television system for receiving a plurality of digitally-encoded television programs includes circuitry for selecting a particular digital data transmission channel from a plurality of digital data transmission channels containing a desired digitally-encoded television program in response to a control signal, at least one of the data transmission channels also including television program schedule data. The system also includes user-operable data entry circuitry for entering data, and a controller for generating the above-noted control signal in response to user-entered data. The controller selects a virtual channel from a plurality of virtual channels in response to user-entered data, each virtual channel being subject to reassignment to a different one of said a plurality of digital data transmission channels, the television program schedule data defining the relationship of each of the television programs to respective ones of the plurality of digital data transmission channels.

Abstract: A television receiver comprises a graphics generator, a video processor, an audio processor, a picture-in-picture processor, and a controller for producing a display of an array of inset images. The controller causes one inset image of the array of inset images to be displayed with an associated graphics image to indicate selection of the one inset image, and causes the reproduction of the audio signal associated with said selected inset image. In one embodiment, all images except the selected one are "frozen", and the selected image is updated in near real time. In another embodiment, a second tuner is tuned to the selected-image channel and is used to provide audio for the selected image, while the first tuner continues to sequentially tune the channels from which all of the images are derived.

Abstract: A system for generating a signal for coupling digital audio, video and data signals in compressed form via a bus. A processing means formats the digital audio, video and data signals into superpackets for transmission via the bus. Each superpacket comprises a timestamp, and a transport packet, representative of the digital audio, video and data signals. The superpackets have a fixed duration and occur at variable intervals. Devices receive the superpacket signal and may utilize the timestamps for clock synchronization. A recording and replay device processes the variable superpacket signal occurrence for recording. Reproduced timestamps are utilized to control restoration of the superpacket signal to have substantially the duration and occurrence as when formatted for bus transmission. A simplified bus couples superpackets between devices. An indicia is added to a superpacket signal to provide automatic control of device bus interfaces.

Abstract: An apparatus having a selectable first mode of operation for clamping an input signal to a first reference level and a selectable second mode of operation for clamping a signal derived from the input signal to a second reference level.

Abstract: A method is disclosed for decompressing in-place an adjusted monotone compressed file having a first portion containing compression codewords and a second portion containing plain text, into a decompressed file having a size and containing plain text. The method comprising the following steps. First, a memory buffer is allocated having the size of the decompressed file. Then the adjusted monotone compressed file is stored in the bottom of the buffer. Finally, the compression codewords in the first portion of the adjusted monotone compressed file are decompressed to produce plain text of a corresponding portion of the decompressed file in the top of the buffer. A method is also disclosed for compressing a source file into an adjusted monotone compressed file. The method comprises the following steps. First, the source file is monotone compressed into a compressed file containing compression codewords.

Abstract: In a tuned switch mode power supply a zero voltage is maintained across a transistor switch, during both turn off and turn on switching transition intervals in the transistor switch. The tuned switch mode power supply operates in a current-mode control, on a current pulse-by-current pulse control basis. A modulator of the power supply includes a pair of transistors that form a regenerative switch to produce a portion of a control signal of the transistor switch that causes the transistor switch to turn off. A transformer-coupled input supply voltage maintains the transistor switch conductive as long as the current in the transistor switch does not exceed the threshold level of a regenerative switch. A resonant pulse is transformer-coupled from the resonant circuit to the regenerative switch for turning off the regenerative switch and for maintaining the transistor switch non conductive after the regenerative switch is turned off.

Abstract: A storage medium format for a storage medium containing packetized data programs includes packet identifiers (PIDs) that identify individual packetized datastreams constituting a program. The data format facilitates the association and assembly of the packetized datastreams of the program by a decoder, independent of PID de-mapping data. The PIDs include a base PID for identifying one datastream and a second PID of predetermined offset value to the base PID for identifying a second datastream. Corresponding packetized datastreams that constitute different programs are given the same PID. The storage medium format may also include program specific information (PSI) suitable for use in recovering data content of a program. The PSI includes an MPEG-like program map table (PMT) and an MPEG-like program association table (PAT) and incorporates a parameter suitable for commanding a decoder to apply the PSI in decoding the program irrespective of previous PSI content.

Abstract: A system for dynamically allocating a resource is disclosed which includes a plurality of resource users and a resource having a maximum utilization level sharable among the plurality of resource users. A plurality of need analyzers, associated with respective resource users, dynamically generate respective signals (COMPLEXITY), each representing the relative need for the resource by the associated resource user. A plurality of access controllers, associated with respective resource users, control access to the resource by the associated user in response to an allocation signal (CONTROL). A resource allocator dynamically generates allocation signals (CONTROL), representing allocated resource utilization levels for associated users, in response to the plurality of need representative signals (COMPLEXITY) from the need analyzers.

Abstract: In a tuned switch mode power supply a zero voltage is maintained across a transistor switch, during both turn off and turn of switching transition intervals in the transistor switch. The tuned switch mode power supply operates in a current-mode control, on a current pulse-by-current pulse control basis. An over-current protection circuit disables the transistor switch when an over-current condition persist longer than a first interval that is substantially longer than a period of a given current pulse in the transistor switch. The operation of the transistor switch is undisturbed, when the over-current condition lasts only a shorter interval than the first interval.

Abstract: In an electronic instrument subject to power line interruptions and having a standby power supply, an external timer is used to time a predetermined brief period (e.g. 15 seconds to 1 minute). If the timer has not yet expired when standby power is once again developed, then a controller will cause a real time clock to start timing, using the currently held time of day. If the timer has expired when standby power is once again developed, the controller will cause the time of day clock to indicate that its time is no longer accurate. Moreover, if the timer has expired, then the controller will not cause the receiver to be turned on. If the timer has not expired, then the controller will determine if the receiver was turned on when the AC power line failure occurred, and if so, the controller will cause the receiver to turn on. If the receiver was turned off when the AC power line failure occurred, then the controller will cause the receiver to remain in standby mode.

Abstract: A controller for a switch mode power supply includes an undervoltage protection circuit responsive to an input supply voltage indicative signal. The input supply voltage indicative signal is also coupled to a foldback point correction circuit. The correction circuit causes a decrease in a maximum duty cycle of a control signal when the input supply voltage increases and is still smaller than a predetermined magnitude. A zener diode limits the input supply voltage indicative signal in a manner to prevent a further decrease in the duty cycle when the input supply voltage exceeds the predetermined magnitude.

Abstract: A television receiver with an MPEG decoder is configurable for full high definition decoding and display, or reduced cost lower definition display. The MPEG decoder (10-33) uses a controllable dual-mode data reduction network selectively employing horizontal detail reduction (29) and data re-compression (30) between the decoder and the decoder frame memory (20) from which image information to be displayed (27) is derived. The amount of data reduction is manufacturer selected in accordance with the resolution of the display device, e.g., equal to or less than high definition resolution. The frame memory size is also manufacturer selected in accordance with the resolution of the display device.