Format Patents (Class 348/469)
  • Patent number: 5831690
    Abstract: A transmission processor (16) receives an input packetized datastream (FIGS. 6-9; FIGS. 15-18 signal A) containing packets of data bytes including MPEG coded video information. The transmission processor outputs a symbol datastream (FIGS. 15-18 signal F) representing a sequence of data fields (FIG. 1) comprising groups of data segments (X) with an associated field sync segment. The transmission processor inserts overhead information. e.g., FEC error coding information, into each data segment, and inserts the longer duration field sync overhead segment between groups of data field segments. The frequency of the transmission processor input byte clock (SC/2, FIG. 6; FIG. 15) an integer sub-multiple of an output symbol clock (SC) frequency. The input datastream exhibits constant uniform inter-packet data gaps and a constant uniform data rate, thereby facilitating the seamless insertion of the field sync overhead segment into the datastream without interrupting the datastream.
    Type: Grant
    Filed: December 6, 1996
    Date of Patent: November 3, 1998
    Assignee: RCA Thomson Licensing Corporation
    Inventors: Paul Wallace Lyons, Alfonse Anthony Acampora
  • Patent number: 5802063
    Abstract: Apparatus in a receiver, for processing transmitted entitlement control information, includes a packet transport processor for selecting signal packets having payloads containing a conditional access payload header and a remaining payload of entitlement data. Respective payload headers include groups of bytes which are coded in a manner to allow or disallow the respective receiver from processing the entitlement data. A conditional access filter preprogrammed with a subscriber specific conditional access codeword examines respective byte groupings of the conditional access header for a match with the subscriber specific conditional access codeword. Only if a match occurs is the processor permitted to process the entitlement data. The entitlement data is thereafter utilized to generate decryption keys for descrambling portions of the transmitted signal.
    Type: Grant
    Filed: October 8, 1996
    Date of Patent: September 1, 1998
    Assignee: Thomson Consumer Electronics, Inc.
    Inventor: Michael Scott Deiss
  • Patent number: 5793433
    Abstract: An apparatus and method for extending the height of an image to display a video signal having a 4:3 aspect ratio on a screen having a 16:9 aspect ratio.
    Type: Grant
    Filed: December 29, 1995
    Date of Patent: August 11, 1998
    Assignee: Samsung Electronics Co., Ltd.
    Inventors: Jeong-Hoon Kim, Min-Seung Lee
  • Patent number: 5767797
    Abstract: A partition decoder system for high definition video decoding receives an HD picture divided into a selected number of sections, each section including identification data including a start code. An FLD detects each start code and assigns a pointer. A selected number of partition decoders, corresponding to the selected number of sections, uses the pointers to select and decode a selected section of the HD picture. The selection is made according to a selected memory management scheme.
    Type: Grant
    Filed: June 18, 1996
    Date of Patent: June 16, 1998
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Jay Yogeshwar, Robert Rozploch, Mikhail Tsinberg
  • Patent number: 5742351
    Abstract: A device for encoding sequences of frames constituted by video-type images of a first frequency (for example, 30 Hz) and film-type images whose original frequency is lower than this first frequency (for example, 24 Hz) and which are converted by means of the "3:2 pulldown" technique.The encoding device comprises;a circuit for detecting the sequences of film-type images from the stream of input data, anda device for preprocessing these sequences for realizing an inverse conversion of the frequency by eliminating, before encoding, the redundant information introduced by the use of the "3:2 pulldown" method.
    Type: Grant
    Filed: October 11, 1995
    Date of Patent: April 21, 1998
    Assignee: U.S. Philips Corporation
    Inventor: Frederique Guede
  • Patent number: 5729298
    Abstract: A television receiver including a teletext decoder for receiving and displaying teletext pages for signalling that a requested teletext has been changed or not changed with respect to the previous consultation of the relevant page. To this end the receiver forms a checkword upon reception of a teletext page, which checkword is representative of the contents of the page, and compares this with the checkword stored upon previous display of the page.
    Type: Grant
    Filed: June 14, 1996
    Date of Patent: March 17, 1998
    Assignee: U.S. Philips Corporation
    Inventor: Rogatus H. H. Wester
  • Patent number: 5713040
    Abstract: A monitor-mode control circuit and method thereof determines a video mode by detecting horizontal and vertical sync frequencies and the polarities of the sync frequencies received from a video card, varies an external resistance value connected to a predetermined port of a microprocessor in accordance with the determined video mode to output a voltage for controlling the picture status of the monitor, in which a program of the microprocessor is changed by a demand of a buyer without changing the hardware to easily correspond to any specification required by the buyer unrestricted by the specification, an external resistance value connected to the predetermined port of the microprocessor at a high or low state is varied to adjust and output voltages of a horizontal size, a vertical size, a horizontal position, a vertical position and a side pin/barrel corresponding to the determined video mode, and a voltage of an oscillating frequency for correcting the synchronization of a picture is output by a pulse width
    Type: Grant
    Filed: April 29, 1996
    Date of Patent: January 27, 1998
    Assignee: Samsung Electronics Co., Ltd.
    Inventor: Ji Young Lee
  • Patent number: 5640210
    Abstract: High definition television coder/decoder a high definition coder or decoder includes a number of parallel sub-decoders or coders. The image to be coded or decoded is divided into a number of stripes, a given stripe being coded or decoded by a single sub-coder or sub-decoder. Every stripe is coded or decoded by the same sub-coder/sub-decoder, where N is the number of sub-coders or sub-decoders. The number of sub-coders is independent of the number of sub-decoders whereby a reduction in the number of sub-coders with increasing bit-rate capacity does not necessitate a change in decoder.
    Type: Grant
    Filed: May 12, 1995
    Date of Patent: June 17, 1997
    Assignee: British Broadcasting Corporation
    Inventors: Michael James Knee, Nicholas Dominic Wells
  • Patent number: 5633686
    Abstract: In an adaptive digital video system, a decoder at a receiving station for a digitally encoded video signal is able to automatically adapt to varying formats and operating modes. All digital video parameters and system operational commands are encoded inband with the digital video serial data stream. The video data is transmitted in successive blocks (e.g., typically an entire image frame or portions thereof) along with system data bytes and control bytes. The data bytes represent the parameters and commands required by the receiver decoder to adapt to the transmitter encoder settings. The control bytes identify the particular parameters and commands represented by respective data bytes. The method is independent of the particular video format or encoding scheme employed, and functions with any transmission medium and bandwidth.
    Type: Grant
    Filed: September 14, 1994
    Date of Patent: May 27, 1997
    Inventor: Scott T. Boden
  • Patent number: 5590153
    Abstract: In order to reduce radio interference jamming in the same channel exerting from an adjacent broadcasting area when a digitized image signal of, for example, high-definition television utilizing an idle channel in ground broadcasting of television is transmitted, a digital string such as a binary coded image signal is thinned out every predetermined digital period so as to be divided into two groups. Continuous digital strings of two series are formed by converting clock rates of the respective groups and converted into multi-value digits. Intermediate carriers are then modulated with the digital signals of the two series having their requisite bands compressed through quadrature modulation to form modulated carriers, and the modulated carriers are transmitted in bands of two divisional channels which escape from adjacent video and voice carriers, the power of which is responsible for the radio interference in the same channel. The carriers are subsequently received for reconstruction.
    Type: Grant
    Filed: July 18, 1994
    Date of Patent: December 31, 1996
    Assignee: Nippon Hoso Kyokai
    Inventors: Yutaka Tanaka, Minoru Honda
  • Patent number: 5563915
    Abstract: A television signal receiving system includes a deinterleaving network (18) containing first and second deinterleaving functions associated with respective memory address controllers (20, 25). One or the other of the deinterleaving functions is selected for use by a multiplexer (30) in response to a Deinterleaver Select control signal. Deinterleaving is accomplished by controlling the read/write addressing of a memory (35) by the selected deinterleaving function.
    Type: Grant
    Filed: November 30, 1994
    Date of Patent: October 8, 1996
    Assignee: Thomson Consumer Electronics Inc.
    Inventor: John S. Stewart
  • Patent number: 5561468
    Abstract: A method and apparatus for transmitting a digital television signal using a single QAM (quadrature amplitude modulated) carrier which provides audio and video data packets at respective complex symbol data rate levels. One purpose of the invention is to provide a digital television signal which resembles the audio vs. video reception characteristics exhibited by conventional analog television (i.e. NTSC). way communication path.
    Type: Grant
    Filed: February 28, 1995
    Date of Patent: October 1, 1996
    Assignee: North American Philips Corporation
    Inventors: David A. Bryan, Samir N. Hulyalkar, Carlo Basile, Zhi-Yuan Guan
  • Patent number: 5508747
    Abstract: A device for converting image signal frame format including a motion compensator for restoring image signals by carrying out motion compensations employing motion information, variable length decoding, inverse multiplex conversion, displaced frame difference, inverse quantization, and inverse discrete cosine conversion. A first frame ratio convertor is used for classifying areas by pixels and converting frame ratios of image signals received from the motion compensator according to the classified areas. The device provides users with the advantage of natural display pictures having good picture quality by carrying out classification of the corresponding pixel areas and subsequent interpolation utilizing various informations applied from an image signal decoder.
    Type: Grant
    Filed: August 5, 1994
    Date of Patent: April 16, 1996
    Assignee: Goldstar Co., Ltd.
    Inventor: Dong H. Lee
  • Patent number: 5499294
    Abstract: A digital camera equipped with a processor for authentication of images produced from an image file taken by the digital camera is provided. The digital camera processor has embedded therein a private key unique to it, and the camera housing has a public key that is so uniquely related to the private key that digital data encrypted with the private key may be decrypted using the public key. The digital camera processor comprises means for calculating a hash of the image file using a predetermined algorithm, and second means for encrypting the image hash with the private key, thereby producing a digital signature. The image file and the digital signature are stored in suitable recording means so they will be available together. Apparatus for authenticating the image file as being free of any alteration uses the public key for decrypting the digital signature, thereby deriving a secure image hash identical to the image hash produced by the digital camera and used to produce the digital signature.
    Type: Grant
    Filed: May 24, 1995
    Date of Patent: March 12, 1996
    Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space Administration
    Inventor: Gary L. Friedman
  • Patent number: 5440432
    Abstract: In an information processor, code errors in a compressed information code train with an added error correction code are corrected using the error correction code. The error corrected compressed information code train is decoded using decoding corresponding to the compression encoding and an information code included in the information code train that is uncorrectable using the error correction code is produced. The compressed information code train inputted to the decoder and the produced information code train are output. The outputted produced information code train is converted into analog data which is output.
    Type: Grant
    Filed: March 14, 1994
    Date of Patent: August 8, 1995
    Assignee: Canon Kabushiki Kaisha
    Inventor: Akio Aoki
  • Patent number: 5430492
    Abstract: For transmitting digital HDTV signals, the HDTV signal, which is either fed with a data rate of .ltoreq.20.48 Mbit/s or which is data-reduced to such a data rate of .ltoreq.20.48 Mbit/s by means of a method utilizing the psycho-optical phenomena of the human eye, is split at the transmitter side of a broadband transmission link operating on the DSR method into two data streams of .ltoreq.10.24 Mbit/s each, and is fed to the I/Q interface of the 4PSK modulator of the DSR transmission link. These two data streams whch are transmitted to the I/Q output of the 4PSK demodulator of the DSR transmission link are then further processed thereat.
    Type: Grant
    Filed: May 12, 1992
    Date of Patent: July 4, 1995
    Assignee: Rohde & Schwartz GmbH & Co. KG
    Inventor: Paul Dambacher
  • Patent number: 5339334
    Abstract: The disclosure relates to methods and apparatus for combining a multiplicity of diversely received replicas of a signal originating in the same remote transmitter. The disclosed methods and apparatus apply, in particular, to digitally modulated sinusoidal prime-carriers or subcarriers, and base the final decision about which of the code alphabet symbols is present in each bit-symbol time slot on either: a) the maximum value of a decision index for each code alphabet letter indicated in/for the same bit time-slot by parallel bit-by-bit detection of the diverse replicas of the signal, the decision index being defined as a function only of the pre-video (IF carrier or subcarrier) signal-to-noise power ratios of the various signal replicas that yield the same code alphabet letter; or on b) bit-by-bit detection of the maximal ratio combination of the video (or pre-bit-detection) bit-stream waveforms out of the prime-carrier or subcarrier exponent (i.e., phase or frequency) demodulators.
    Type: Grant
    Filed: December 20, 1991
    Date of Patent: August 16, 1994
    Inventor: Elie J. Baghdady
  • Patent number: 5329365
    Abstract: A compression/decompression system includes a source of (1:1 60 Hz) non-interlaced scanned video signal. A preprocessor constructs (2:1 60 Hz) interlaced scanned video signal from the non-interlaced scanned video signal by selection of alternate lines of successive non-interlaced image signals. The interlaced scanned video signal is compressed according to an MPEG protocol of I, P and B frame compression algorithms. I, P and B frame compression is performed such that there are an odd number, greater than one, of B-frames between successive I/P frames (for example the sequence of compressed frames may conform to I, B1, B2, B3, P, B1, B2, B3, P, B1, B2, B3, I, B1, . . . etc). The I compressed frames, the P compressed frames and alternate B compressed frames (the frames B2 in the exemplary sequence) selectively form a primary compressed (2:1 30 Hz) interlaced video signal for reproduction by interlaced scanned receivers. The intervening B-frames selectively form a secondary compressed video.
    Type: Grant
    Filed: July 7, 1993
    Date of Patent: July 12, 1994
    Assignee: RCA Thomson Licensing Corporation
    Inventor: Kamil M. Uz
  • Patent number: 5325204
    Abstract: A digital notch filter apparatus for removing narrowband interference signals from a wideband communication signal. The apparatus includes a recursive digital passband interference acquisition filter, an acquisition mode center frequency control circuit, a recursive digital passband interference tracking filter, a tracking mode center frequency control circuit and an interference detection circuit. The tracking filter has a narrower bandwidth than the acquisition filter. Both the acquisition and tracking filters are gang tuned so that the center frequencies of their passbands are adjusted in unison. During interference acquisition mode, the acquisition mode center frequency control circuit is used is to adjust the center frequency of the filters over the bandwidth covered by the interference canceler.
    Type: Grant
    Filed: October 8, 1993
    Date of Patent: June 28, 1994
    Assignee: Hitachi America, Ltd.
    Inventor: Carl G. Scarpa
  • Patent number: 5321440
    Abstract: Image data is encoded into sync blocks of fixed length and maximum data volume by dividing a vertical interval of image data samples, such as a field or frame of samples, into a plurality of blocks and deriving the orthogonal transform of the image data samples in each block. A block of conversion coefficients that are produced by the orthogonal transform are quantized with the same quantizing step to produce weighted, quantized conversion coefficients having a weighting factor that is a function of the visual activity of that block. Then, the weighted, quantized conversion coefficients of a block are variable length coded and the variable length codes of a predetermined number of blocks are combined into a sync block of fixed length.
    Type: Grant
    Filed: June 2, 1992
    Date of Patent: June 14, 1994
    Assignee: Sony Corporation
    Inventors: Naofumi Yanagihara, Michio Nagai
  • Patent number: 5313279
    Abstract: In a high definition television signal encoder, high priority and standard priority digital data are each separated into quadrature I and Q components, spectrally shaped by digital filtering, and time division multiplexed to produce respective quadrature amplitude modulated signals of the 32-QAM type. The high priority QAM signal and the standard priority QAM signal exhibit different bandwidths and carrier frequencies. The high priority and standard priority QAM signals are combined in digital form to produce a prioritized dual 32-QAM digital signal before being conveyed to a single analog-to-digital converter and analog RF transmission networks.
    Type: Grant
    Filed: December 16, 1992
    Date of Patent: May 17, 1994
    Assignee: Thomson Consumer Electronics
    Inventors: Tian J. Wang, Lauren A. Christopher
  • Patent number: 5309235
    Abstract: A system and method for transmitting digital data in the horizontal overscan portion of a composite video signal is presented. A source supplies digital data which is encoded by a 32-state QAM encoder using a symbol clock having a frequency, 4 times the color subcarrier frequency (, then the encoded data is quadrature amplitude modulated using a carrier signal with a frequency of /2. The modulated digital data replaces the video signal in the horizontal and vertical overscan portions of the baseband video signal. The video signal is received, the modulated digital data is extracted from the video signal, demodulated using QAM techniques, and decoded with a reconstructed version of the symbol clock.
    Type: Grant
    Filed: September 25, 1992
    Date of Patent: May 3, 1994
    Assignee: Matsushita Electric Corporation of America
    Inventor: Saiprasad V. Naimpally
  • Patent number: 5309234
    Abstract: A video display control system automatically controls a video display responsive to detection of letterbox format input video signals having varying format display ratios. A detection circuit continuously detects the first and last lines of active video in a video signal. A memory stores scan line numbers corresponding to the first and last lines of active video. The height of the picture is determined from the scan line numbers of the first and last lines of active video. The picture height is indicative of the format display ratio of the letterbox input. A comparator circuit compares the picture height to a threshold corresponding to the widest expected format display ratio of a letterbox input signal.
    Type: Grant
    Filed: January 21, 1993
    Date of Patent: May 3, 1994
    Assignee: Thomson Consumer Electronics
    Inventors: Greg A. Kranawetter, Timothy W. Saeger, Donald H. Willis
  • Patent number: 5309450
    Abstract: An error correction coding method and apparatus which can correct errors generated during the transmission or the storage, or the receiving or the reproducing of a digital image. The error correction coding method according to the present invention comprises the steps of: dividing one image into blocks to prevent the deterioration of the quality of a screen by preventing the generation of burst errors in a header during the transmitting or storing of the image information in the form of digital signals; compressing and coding each divided block into a block code having a header and video information; separating and arranging the compressed and coded header and video information so that successive headers do not overlap; and adding parity data into the separated and arranged header and video information. The apparatus for carrying out the error correction coding method of the present invention comprises an image divider, a data compressor, a parity data insert portion, and a data interleave portion.
    Type: Grant
    Filed: April 29, 1991
    Date of Patent: May 3, 1994
    Assignee: Samsung Electronics Co., Ltd.
    Inventor: Gye-jong Kim
  • Patent number: 5305104
    Abstract: In an Enhanced Definition Television (EDTV) system, an assistance signal is transmitted to enable a suitably equipped receiver to choose from a number of predetermined deinterlacing modes. The modes represent interpolation options for estimating lines missing in a current interlaced image field, thereby enhancing the vertical resolution of a display. For example, five options may be provided for as follows: (1) intra-frame linear interpolation, (2) use of information from a preceding frame, (3) use of information from a succeeding frame, (4) combining the results of (1) and (2), and (5) combining the results of (1) and (3). Preferably, interpolation options are derived on a block basis and transmitted with coded motion vectors which may be compressed to make maximum use of the available bandwidth. The assistance signal may be transmitted within the vertical and/or horizontal blanking intervals of an interlaced television broadcast.
    Type: Grant
    Filed: July 27, 1992
    Date of Patent: April 19, 1994
    Assignee: The Trustees of Columbia University in the City of New York
    Inventors: Daryl K. Jensen, Dimitris Anastassiou
  • Patent number: 5303038
    Abstract: For the possibly simultaneous A/D conversion of two color difference signals of a first picture signal as well as a carrier-frequency chrominance signal of a second picture signal, a relevant circuit arrangement is provided with a multiplexer (3) by which a time-division multiplex signal is generated from the two color difference signals, in which time-division multiplex signal the two color difference signals alternate in time and which is added to the chrominance signal in an adder (5) to form a sum signal which is applied to an A/D converter (10) which is followed by a separating filter (11) for separating the digital time-division multiplex signal from the digital chrominance signal.
    Type: Grant
    Filed: September 5, 1991
    Date of Patent: April 12, 1994
    Assignee: U.S. Philips Corporation
    Inventors: Hermann Treber, Eckhart Pech
  • Patent number: 5301031
    Abstract: A display apparatus using a matrix display panel, such as a liquid crystal panel, for converting the number of scanning lines to be displayed to a number that can be accommodated on a panel having a smaller number of scanning lines. The apparatus includes a control circuit which produces control signals in synchronism with the input video signal, horizontal and vertical scanning circuits each including a shift register operated by the control circuit, and a display panel which is formed of a matrix arrangement of pixels that are driven selectively by the scanning circuits. The apparatus further includes a circuit which halts the operation of the vertical shift register at a certain interval within the effective scanning period of the vertical scanning circuit so as to extract vertical shift clocks, thereby removing the vertical shift clocks within the effective display period of the video signal, thereby extracting periodically extracting scanning lines.
    Type: Grant
    Filed: September 2, 1992
    Date of Patent: April 5, 1994
    Assignee: Hitachi Ltd.
    Inventors: Masahiro Eto, Nobuaki Kabuto, Mitsuo Tanaka
  • Patent number: 5299014
    Abstract: A high definition video signal can be obtained from photographic film by a non-real time scanning operation. The image area to be scanned is divided into blocks and a number of subscans equal to the number of pixels in each block are performed on the image area. In each scan, a different pixel in each block is scanned so that after n scans all pixels in the n pixel blocks have been scanned and a composite video signal can be formed. A plurality of high definition frames are stored at less than real time in a multi-frame store and then read out in real time to give a continuous high definition playback.
    Type: Grant
    Filed: January 19, 1993
    Date of Patent: March 29, 1994
    Assignee: Rank Cintel Ltd.
    Inventors: Peter W. Stansfield, Trevor M. Osborne
  • Patent number: 5291286
    Abstract: A vector quantizer which transmits the input vector of the time when the minimum distortion is larger than the preset distortion threshold value and stores such input vector into the second code book as the new quantizing representative vector for the use in the successive vector quantizing processes.Further, since the first and second code book constitute in the form of tree-structure, calculation for search may be executed at a high speed.
    Type: Grant
    Filed: February 9, 1993
    Date of Patent: March 1, 1994
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Tokumichi Murakami, Koh Kamizawa, Atsushi Itoh, Yoshiaki Kato, Yuri Hasegawa, Kazuhiro Matsuzaki, Takahiro Fukuhara
  • Patent number: 5291289
    Abstract: A method and apparatus for modulating and demodulating an MCM television signal is described which is particularly useful in proposed "simulcast" HDTV terrestrial broadcasting. The MCM spectrum of the television signal is shaped using weighting coefficients which are derived from either an idealized NTSC signal or an actual NTSC co-channel signal. These coefficients are used to shape the respective MCM carriers to provide an energy distribution in the MCM signal which provides greater degree of robustness with a minimum degree of co-channel interference to and from an NTSC co-channel signal. The instant invention further takes advantage of the interference characteristics of composite television signals described above, to position the placement of the MCM carriers in frequency, to minimize interference with an NTSC co-channel signal.
    Type: Grant
    Filed: March 20, 1992
    Date of Patent: March 1, 1994
    Assignee: North American Philips Corporation
    Inventors: Samir N. Hulyalkar, David A. Bryan, Carlo Basile
  • Patent number: 5291291
    Abstract: A system for minimizing co-channel interference into NTSC receivers from digitally transmitted ATV signals. The NTSC receiver subjective random noise sensitivity characteristic is utilized to shape the ATV transmitter power curve. A complementary filter incorporated in ATV receivers for compensating for the shaped ATV transmitter power curve. The shaped ATV power curve emphasizes signals at the frequencies where the NTSC subjective random noise sensitivity is low and deemphasizes signals at the frequencies where the NTSC subjective sensitivity is high.
    Type: Grant
    Filed: April 8, 1992
    Date of Patent: March 1, 1994
    Assignee: Zenith Electronics Corp.
    Inventor: Carl G. Eilers
  • Patent number: 5287178
    Abstract: A video signal encoding system includes a signal processor for segmenting encoded video data into transport blocks having a header section and a packed data section. The system also includes reset control apparatus for releasing resets of system components, after a global system reset, in a prescribed non-simultaneous phased sequence to enable signal processing to commence in the prescribed sequence. The phased reset release sequence begins when valid data is sensed as transiting the data lines.
    Type: Grant
    Filed: July 6, 1992
    Date of Patent: February 15, 1994
    Assignee: General Electric Company
    Inventors: Alfonse A. Acampora, Richard M. Bunting
  • Patent number: 5287188
    Abstract: A video system comprises a video display having a wide format display ratio for displaying a video signal. A signal processor has an interpolator and a first in first out line memory having asynchronous write and read ports for selectably expanding and compressing a picture represented by data in the video signal. The picture is cropped to define a subset of the picture for display by controlling writing of the data into the line memory. A microprocessor for controls provides control signals with selectable time durations and selectable phases relative to a synchronizing component of said video signal for selecting boundaries of the subset of the picture for display. The microprocessor can select the time durations and the phases responsive to user commands.
    Type: Grant
    Filed: January 7, 1992
    Date of Patent: February 15, 1994
    Assignee: Thomson Consumer Electronics, Inc.
    Inventors: Timothy W. Saeger, Nathaniel H. Ersoz
  • Patent number: 5285276
    Abstract: A frame of compressed video data is formatted for transmission into a plurality of data segments, a first group of which are encoded in the form of a plurality of four-level symbols and a second group of which are encoded in the form of a plurality of two-level symbols for providing improved noise performance. The partition between the first and second groups of data segments may be established on a fixed basis, a variable basis dependent upon the effective level of compression, or a combination of both. Preferably, the levels are selected such that the average levels of the transmitted M and N-level symbols are substantially equal to a non-zero value to assist lock-up of the receiver PLL and reduce transmission power.
    Type: Grant
    Filed: May 25, 1993
    Date of Patent: February 8, 1994
    Assignee: Zenith Electronics Corp.
    Inventor: Richard W. Citta