Abstract: An auxiliary digital data extractor in a television receiver includes a source of a composite video signal. The composite video signal includes an auxiliary digital data component which is either a first frame code having a predetermined number of bits and auxiliary data in a first format, or a second frame code having the same number of bits and auxiliary data in a second format. A frame code detector is coupled to the composite video signal source. The frame code detector is responsive to one subset of the frame code bits to detect the first frame code and to a different subset of frame code bits to detect the second frame code. An auxiliary data utilization circuit is coupled to the composite video signal source and the frame code detector. The auxiliary data utilization circuit receives auxiliary data in the either first format when the first frame code is detected or the second format when the second frame code is detected.

Abstract: Information is coupled to a data bus such as an I2C data bus using a push-pull circuit. The push-pull circuit provides for communicating on the data bus at two different data rates. The push-pull circuit includes an active pull-up device that is enabled during a first push-pull mode of operation for providing a high data rate. During a second normal mode of operation, the active pull-up device is disabled providing a low data rate. When the active pull-up device is deactivated, the clock and data buses are driven by the external resistors connected thereto at a data rate lower than the data rate during the first mode.

Abstract: A graphical on-screen display (OSD) system, includes a decoder for decoding graphical OSD image representative data from an auxiliary information component of a video signal. An edge detector is coupled to the decoder and processes the OSD image representative data to detect an edge in the graphical OSD image. An edge smoother is coupled to both the decoder and the edge detector and generates signals representing a reproduced OSD image having a smoothed edge when an edge is detected.

Abstract: A decoder for decoding data from a data signal component of a television signal, such as closed caption data, decodes the data signal in response to a deflection signal during a normal mode of operation of a television receiver and in response to separated sync signal during a standby mode of operation of the television receiver.

Abstract: A color interpolation circuit allows information uniquely identifying one of six colors to be stored by using only two binary bits of memory storage, and allows information uniquely identifying one of 120 colors to be stored by using only four binary bits of memory storage. This is accomplished by storing only the foreground, edge, and background colors (i.e., herein referred to as "independent" colors), and an "interpolate operator" code, and by providing circuitry to properly interpret and process the interpolate operator code to generate "intermediate colors". This permits a 33% reduction of memory size and reduces the "fetch speed" requirements of associated on-screen display (OSD) scan converter circuitry.

Abstract: An auxiliary video information decoder for extracting an auxiliary video information signal from a video signal includes a data slicer and apparatus for adjusting the slicing level of the data slicer. The slicing level is adjusted rapidly until a reference component of the auxiliary information signal is detected during a display interval of the video signal in which auxiliary video information is expected to occur. A count is incremented after display intervals in which the reference component is detected and is decremented after display intervals in which the reference component is not detected. Slicing level adjustment ceases while the count is at least a predetermined number. The apparatus rapidly adapts the slicing level to long-term video signal amplitude changes of significant magnitude (e.g. following a channel change) and maintains a constant slicing level when transient variations occur in the video signal amplitude.

Abstract: An auxiliary video information decoder for decoding information such as closed caption data in a video signal identifies a desired horizontal line of video in a video signal. A reference pulse in a synchronizing signal is detected followed by the generation of first and second window pulse signals occurring at predetermined delays after detection of the reference pulse. A pulse occurring in the synchronizing signal during the window pulses indicates the start of the desired horizontal line interval. A field identification signal may also be generated. Features for improving noise and phase error immunity when identifying a video line are provided.

Abstract: A data slicer for extracting auxiliary video data from a video signal adapts a data slicing level to the amplitude of the data signal as indicated by the average value of a run-in clock (RIC) signal that is included in the video signal. Control of the slicing level occurs during a window interval that spans an integral number of cycles of the RIC signal. The presence of the RIC signal within the window interval may be verified as part of the slicing level adjustment operation. The data slicer is suitable for implementation in a digital integrated circuit.

Abstract: A data slicer for extracting auxiliary video data from a video signal adapts a data slicing level to the amplitude of the data signal as indicated by the average value of a run-in clock (RIC) signal that is included in the video signal. Control of the slicing level occurs during a window interval that spans a portion of the RIC signal. A comparator compares the video signal to a slicing level established at the output of a digital to analog converter. A digital system monitors the output of the comparator during the RIC window to determine both the existence of auxiliary video data and the accuracy of the slicing level. The slicing level is adjusted in response to the comparator output to establish a slicing level related to the RIC signal amplitude.

Abstract: A horizontal line counter (110,115,120) provides a signal (LINE #21) identifying the beginning of video data in a particular horizontal video line. The counter is clocked by multiple clock signals. A first clock signal (HOR PLS) clocks the counter until the line count value equals a known value that is less than the line number of the horizontal line that is to be identified. When the count value equals the known value, clocking by a second clock signal (COMP SYNC) is enabled. Although, the first clock source provides a regular pulse waveform suitable for clocking the counter reliably, transitions on the first clock signal may not accurately indicate the beginning of information within a horizontal line interval. Transitions on the second clock signal accurately indicate the beginning of the desired information.

Abstract: In a system for identifying specific horizontal lines of video that are included in a video signal, a horizontal line counter (100) is cleared to indicate the beginning of a vertical interval by a reset signal (VERDEL) derived from a vertical sync signal (VER). The line counter is clocked by a signal (HOR) at the horizontal sync rate that is derived from a harmonic (N.sub.-- FH) of the horizontal sync signal. The relative phase shift between the reset and clock signals for the horizontal line counter is measured (105,120). The measured phase shift is used as an input to a variable phase shifter (110) to adjust the phasing between the horizontal line counter control signals and the original sync signals. The phase adjustment permits significantly decreasing the sensitivity of the horizontal line counter to jitter of vertical sync.

Abstract: A system for processing auxiliary video information, such as closed caption information, includes capability for detecting invalid parity errors that may be created by video signal distortion effects caused by sync suppression video signal scrambling. The sync suppression distortion does not affect the video display but may modify the parity bit of the second of two closed caption characters in each occurrence of line 21 of field 1 causing invalid parity errors. Parity errors in the first character, which is unaffected by the sync suppression distortion, indicate whether valid parity errors exist in the second character. If no parity errors occur in the first character, parity errors that occur in the second character are considered to be invalid.

Abstract: An auxiliary video data decoder provides for correcting synchronization error between a sync signal and a video signal that may contain auxiliary video data. Cycles of a reference waveform included in the auxiliary video data are counted during a timing window to determine if synchronization is correct. An incorrect count indicates a synchronization error exists. The window timing is adjusted with respect to the sync signal. The timing test is repeated. Repeated failure of the test indicates that auxiliary video data does not exist in the video signal.

Abstract: An indication of stability of a tuning system after changing, the local oscillator frequency to a predetermined frequency, such as a frequency corresponding to a new channel during a channel changing operation or to a new search frequency during a search, is provided by monitoring an AFT signal during the frequency changing operation and determining when it remains consistent for a predetermined time.

Abstract: A tuning system of a television receiver includes a digital automatic fine tuning (AFT) unit for generating a digital AFT signal representing the deviation of the frequency of the picture carrier of the IF signal from a nominal frequency. The digital AFT unit includes a counter for counting cycles of picture carrier during repetitive counting intervals which occur during a measurement period having a duration at least as long as the duration of one field of a television signal. The duration and spacing of the counting intervals are selected so that at least one counting interval occurs during the vertical blanking interval in which the picture carrier is not likely to be over-modulated and therefore not likely to result in erroneous low counts. The contents of the counter are evaluated at the end of each counting cycle to determine if a first count corresponding to a nominal frequency or a second count corresponding to the frequency having a positive frequency deviation have been produced.

Abstract: A tuning system of a television receiver includes a digital automatic fine tuning (AFT) unit for generating a digital AFT signal representing the deviation of the frequency of the picture carrier of the IF signal from a nominal frequency value. The digital AFT unit includes a counter for counting cycles of picture carrier during counting intervals. A portion of the IF section, the counter and at least of a portion of the signal processing section of the television receiver are included within a single integrated circuit. A microprocessor is coupled to the integrated circuit through a serial data bus. Under software program control, the microprocessor (1) transmits function control and counting control information to the signal processing section through the serial data bus, (2) receives count information from the counter through the serial data bus, and (3) evaluates count information to determine the deviation of the frequency of the IF picture carrier from its nominal frequency value.

Abstract: A tuning system includes a microcomputer-based synchronization signal detector which does not require the use of a hardware timer/counter. The microcomputer samples the output signal of a sync separator coupled to an ordinary input/output port during a number of different evaluation intervals to determine if respective characteristics of a valid sync signal occur. During one evaluation interval, a test is performed to determine if a "high" level is present for a time duration less than a given time duration (e.g. 10 .mu.S) corresponding to the maximum duration of horizontal sync pulses. During another evaluation interval, a test is performed to determine if a "low" level is present for a time duration greater than another given time duration (e.g., 40 .mu.S) corresponding to the minimum separation between horizontal sync pulses. The sampling intervals and evaluation intervals are established by the time required to execute instruction cycles.

Abstract: A television tuning system includes control apparatus for changing the frequency of a local oscillator signal during a search and a comparator arrangement for determining when an AFT signal traverses first and second threshold values corresponding to first and second frequencies in respective "hump" regions of the AFT signal. The frequency of the local oscillator is set to the average of the first and second frequencies in order to set the frequency of the IF picture carrier closer to the nominal value than the first and second frequencies.

Abstract: A tuning system for tuning non-standard frequency RF signals which utilizes searches for non-standard RF signals by examining both a synchronization component and an AFT signal at each of a successive number of search frequencies. If the AFT signal indicates the detection of a carrier, the frequency at which this occurs is stored. However, this frequency is not caused to be tuned unless the search has been completed and the synchronization signal has not indicated the presence of a carrier. Thus, the reliability afforded by the synchronization component is maintained while adding the capability for tuning scrambled channels.

Abstract: A tuning system for tuning non-standard frequency RF television signals provided by cable distribution networks and television accessories conducts first and second consecutive searches by changing the local oscillator frequency. The first search is limited to search frequencies corresponding to predictable non-standard frequencies associated with the major cable distribution networks. The second search includes more search frequencies and extends over a wider frequency range than the first. During an auto-programming mode, in which active channels are identified, for memorization in a channel list portion of a memory, only the first search is conducted to minimize the required time.