Abstract: A conferencing server accepts a conferencing session call from a conferencing node over a communications link. The conferencing server receives a message from the conferencing node requesting confidence testing over the communications link. The conferencing server transmits confidence test signals to the conferencing node over the communications link for playing by the conferencing node. The conferencing server receives a status of the playing of the confidence test signals from the conferencing node. The conferencing server transmits the status of the playing of the confidence test signals to a customer support node.

Abstract: An attachment is arranged to permit channel metering of any of a variety of receivers which incorporates serial data communication buses. The attachment includes a computer for reading channel information carried by the serial data communication bus of a monitored receiver, a field programmable gate array which may be programmed to customize the attachment to the serial data communication bus arrangement and to the data format of any of a wide variety of receivers, and an isolator to isolate the attachment from the monitored receiver.

Abstract: A method and apparatus for objectively measuring the image quality of a destination video signal generates measurement parameters that are indicative of human image quality perceptions. Subjective human test panel results are generated for a variety of test scenes and types of image impairment. Objective test results are also generated by the apparatus of the present invention for the variety of test scenes and image impairments. A statistical analysis means statistically analyzes the subjective and objective test results to determine operation of the apparatus. Accordingly, when the apparatus extracts test frames from the actual source and destination video signals and compares them, image quality parameters are output by the apparatus which are based on human image quality perceptions.

Abstract: An in-service hum and low frequency distortion measurement technique for in-service cable television channels having a video modulated carrier frequency obtains peak samples of the horizontal sync signal to effectively filter out the vertical interval frequency. The data record formed by the peak samples is filtered and input to a fast Fourier transform to obtain magnitude values for the fundamental and first harmonic frequency components corresponding to a powerline. From these magnitude values hum and low frequency distortion is computed as a percentage relative to the amplitude of the carrier frequency. The same procedure may be used with an input CW signal in an out-of-service measurement for hum only, the difference between the in-service and out-of-service measurements determining the low frequency distortion due to the video signal.

Abstract: An image processing system with self monitoring includes an image acquisition module for acquiring data corresponding to an image, and one or more image processing modules. The acquisition module interleaves the variable (and therefore unpredictable) image data with diagnostic data to provide known diagnostic data. The image processing modules process the diagnostic data together with the image data to monitor system performance.

Abstract: In an automatic cable attenuation compensation system comprising a fixed compensation part (FC-R/G/B) providing a stepwise adjustable attenuation compensation for substantially compensating cable attenuation, the stepwise adjustable attenuation compensation of the fixed compensation part being set after power-up, an adaptive compensation part (VC-R/G/B) is provided for a continuously active compensation for a further accurate compensation of the cable attenuation.

Abstract: A UHF carrier signal modulated by a video signal, where the frequency and the format of a line synchronization signal are known, is transmitted in a transmission region in a confined medium by a microwave link. In a reception region, two signals are received along two angularly offset privileged axes, each is frequency-demodulated along identical processing channels, the existence in the signal emitted from one of the channels, the "starting channel", of a periodic signal with the line synchronization frequency is checked and this signal is selected if the check proves positive. If the periodic signal disappears, the test is applied to the other channel; if that check is positive, this other channel is selected until this periodic signal disappears. Such a process is especially applicable in tunnels.

Abstract: Apparatus for use in calibrating a display system comprising digital-to-analogue converters (D.A.C) (11,12,13) for converting a digital colour control signal to analogue colour component signals which are suitable for controlling an electronic display. An analogue signal modifier modifies the signals from the D.A.C. The apparatus also comprises a switch (10) for connecting between the D.A.C. and the analogue signal modifier. The switch is operable in a first mode (52,54) to pass signals from the D.A.C. (11,12,13) directly to the analogue signal modifier or in a second mode (53) to pass analogue calibration colour component signals to the analogue signal modifier such that the appearance of the signals from the D.A.C. and the calibration signals can be visually compared on a screen (17) to determine whether any reproduction errors are in the D.A.C. (11,12,13) or in the signal modifier.