Abstract: A monitor interface cable for transmitting display data and command data between a computer system and a display monitor preferably including a microcontroller. The monitor interface cable enables both display and command data to be transmitted simultaneously from the computer system to the display monitor.

Abstract: A monitor interface cable for transmitting display data and command data between a computer system and a display monitor preferably including a microcontroller. The monitor interface cable enables both display and command data to be transmitted simultaneously from the computer system to the display monitor. Inside the computer system, data containing the commands written to a particular memory location in a video buffer card is applied to various signal lines located in the monitor interface cable. These signal lines are coupled to the microcontroller located in the display monitor which receives the commands and performs various controlling functions in response. Status information in the form of a command is transmitted back across a second signal line to the computer system where various software programs including drivers receive and process the status information. Display data is simultaneously transmitted over other signal lines also located in the monitor interface cable.

Abstract: Electromagnetic interference ("EMI") is reduced in a CRT video display system by spreading-out the EMI-producing spectra present in the video pixel data and/or clock signals. A clock dropping circuit coupled between the display generator main oscillator and the timing generator periodically phase-modulates the timing generator clock signal such that it comprises N phases, where N.gtoreq.2. As a result, each horizontal line of video data and the horizontal synchronization signals is phase shifted. This dual-shifting effect eliminates display image distortion that would result if only the video signal were shifted. Video distortion is further minimized by deriving the horizontal and vertical synchronizing signals from a common constant clock. EMI energy associated with each clock harmonic is spread by a frequency amount .DELTA.f proportional to the rate of phase change in the clock signal, the rate of phase change exceeding half the bandwidth f.sub.m of a standard EMI measurement reference window.

Abstract: Arrayed display pixels are coupled such that all row pixels are coupled together by a row conductive element and all column pixels are coupled together by a column conductive element. The row-coupled pixels are driven by first and second row drivers and the column-coupled pixels are driven by first and second column drivers, a total of four drivers in all. The drivers each output time-varying signals of different frequencies. The vertical scan rate is determined by the frequency differential in the signals output by the two row drivers, and the horizontal scan rate frequency is determined by the frequency differential in the signals output by the two column drivers. The absolute frequencies of the four signals are set proportional to the propagation delay of the medium through which the driver signals travel. The invention implements a pixel enabling signal using the beat-frequency difference between two driver source signals that propagate through a pixel string from opposite ends of the string.

Abstract: Electromagnetic interference ("EMI") generated by a flat panel video display system is reduced by periodically phase/modulating the panel clock. This spreads EMI energy associated with each panel clock harmonic by a frequency amount .DELTA.f proportional to the rate of phase change in the panel clock signal. EMI energy associated with each panel clock harmonic is reduced relative to a square-wave panel clock signal because the same energy is now spread over a group of frequencies centered about each harmonic. The phase of the panel clock is changed at a rate exceeding the bandwidth f.sub.m of a standard EMI measurement reference window. This disperses adjacent spectral energy sufficiently so the reference window measures but one, decreased, amplitude at a time. Phase-modulation may be achieved using a clock pulse dropping circuit that receives a square-wave input of frequency Nf.sub.

Abstract: Video signals for each primary color are delayed in time relative to every other primary color video signals. When displayed on a cathode ray tube ("CRT") display, the time delayed video signals will result in a separated color pattern for each image displayed. Separated color images are subsequently realigned through use of electron beam deflection controls affecting the horizontal and vertical displacement of electron beams for each color. Measurement of EMI at a far field point varies between zero (no EMI) and no reduction in measurable EMI, depending on the frequency of the video signals and the amount of time delay induced therein. In alternative embodiments, time shifting of video signals may be accomplished either by discrete filter components, simple propagation delay lines.

Abstract: Visible Moire interference is eliminated by alternately shifting the phase of the horizontal sync signal or video signals such that the phase of each video line, and hence the phase of the resulting Moire interference associated with that video line, is also alternately shifted. The phase of the Moire interferences are shifted such that persistence of vision in the human eye averages oppositely phased phosphor intensity variations occurring on alternating scan lines and/or vertical fields. When viewed by a user of the CRT, optical cancellation of the Moire interference patterns results.

Abstract: A multiplier for multiplying the modulated sound and picture carriers to produce an intercarrier sound signal in a quasi-parallel sound channel of an IF section has a pair of anti-parallel connected diodes in a limiter for generating an amplitude limited version of the picture carrier. It has been discovered that the varying capacitance of the diodes with picture amplitude can cause phase shifts and hence phase modulation interference in the intercarrier signal. The latter is especially troublesome for stereo sound reproduction. To reduce such interference, a low value resistor is shunt coupled to the diodes to inhibit the capacitance variations of the diodes and resulting undesired phase modulation in the intercarrier sound signal.

Abstract: A circuit has two signal paths. The first path provides a signal with a selected magnitude and phase. The second path selectively provides either no signal or a signal with twice the magnitude and opposite phase with respect to that provided by said first path. The signals of the two paths are combined to provide a signal with a selectable phase. The circuit can be used in a stereo decoder in which an L+R stereo sum signal is combined with an expanded R-L stereo difference signal, provided by an expander also used for a SAP signal, to produce left (L) and right (R) stereo signals so that when the SAP signal is being reproduced, it is of the same phase in both left and right channels.

Abstract: In a television signal processing apparatus, a phase-locked loop (PLL) is provided for detecting the audio information from the television signal and for providing a defect control signal which, when applied to compensation circuitry, reduces impulse noise effects in the video information. The PLL includes a phase detector, a lowpass filter (LPF) and a voltage controlled oscillator (VCO). The phase detector has a first input coupled to be responsive to the frequency modulated sound signal produced by the tuner, a second input coupled to be responsive to the output of the VCO and an output coupled to the LPF. The LPF provides a phase control signal to the VCO and provides the detected audio information. A signal mixer serving as a synchronous detector has first and second inputs coupled to the first and second inputs, respectively, of the phase detector and has an output for providing the defect control signal indicative of the amplitude variations of the frequency modulated sound carrier.

Abstract: A frequency translation phase-locked loop (PLL) is provided for detecting the audio information from a received television signal. The PLL includes a switching arrangement which, in a first position causes the loop to process the IF picture and sound carriers for detecting the audio information in an intercarrier type of detection method and, in a second position causes the loop to process the IF sound carrier for detecting the audio information without the use of the received picture carrier, in a "separate" (split-sound) type of audio detection method.

Abstract: A frequency translation phase-locked loop (PLL) is provided for detecting the audio information from a television signal. A voltage controllable oscillator having a nominal oscillation frequency equal to the frequency difference between the intermediate frequency (IF) picture and sound carriers provides one input to a mixer and a substantially unmodulated picture carrier is supplied as the other input to the mixer. A phase detector has as its first input the output signal from the mixer and as its second input the sound carrier. A lowpass filter coupled between the output of the phase detector and a control input to the VCO completes the PLL. The detected audio information is provided at the output of the lowpass filter.