International Business Machines Corporation

Karl J Kuhn

John Mark Zetts

Leonard DeGollado

Leung Ping Lee

An apparatus and method provide non-intrusive in-service testing of audio/video synchronization testing without using traditional audio marker tones. The network includes an A/V synchronous test signal generator which injects video and audio markers into the video and audio non-intrusively and routes the two signals into a switch where they are switched into a channel for encoding and transmission via the ATM network. At the distant end the signal is decoded and routed by a switch into the A/V test generator and measurement set where the markers are detected and the A/V skew calculated, after which the audio and video are routed to the subscriber. The A/V test set signal generator includes a Video Blanking Interval (VBI) test signal generator and a white noise generator, the former injecting a marker into the video signal and the later injecting an audio marker into the audio signal. The video marker is injected into the VBI and broadband, background audio noise to measure the delay between the audio and video components of a broadcast. The marking of the audio is accomplished by gradually injecting white noise into the audio channel until the noise level is 6 dB above the noise floor of the audio receiver. As a precursor A/V sync signal, a small spectrum of the white noise is notched or removed. This signature precludes inadvertent recognition of program audio noise as the audio marker.

Apparatus and method of in-service audio/video synchronization testing

A switched, digital high-broadband network provides automated control and in-service and out-of-testing of analog video signals, encoded and decoded real time, into MPEG 2 digitized format with a high level of security and protection of content and without attendant degradation of the analog signal sometimes experienced in satellite transmissions. The switch network, typically an asynchronous transfer mode (ATM) network, has multiple gateways for connection to video signal sources and sinks. Each gateway includes an analog/digital video switch for receiving the video signals and distributing them to an MPEG 2 encoder for conversion into digital packets. A multiplexer is coupled to the encoder and a digital switch for inserting the multiplexed signal into the switched ATM network. The multiplexer and the digital switch encode destination address information into the digital packets to ensure proper routing. Each gateway further includes a de-multiplexer and MPEG 2 decoder connected to the digital switch for separating the digital packets from the ATM network into separate MPEG 2 streams subsequently decoded into analog video and returned to the video sinks. A command and control center is coupled to each gateway for remote testing of point-to-point and point-to-multipoint circuits; testing a switch circuit before and after the establishment of a connection to a customer; in service testing of MPEG 2 encoding content; detecting and isolating digital network problems, and off-line network testing and automating network utilization. The command and control center includes test executives which ensure the quality and availability of video traffic. The test executives run continuously run without manual intervention providing network operators with network status through user consoles.

System and method of automated testing of a compressed digital broadcast video network

A switched digital video broadcast network provides in-service testing of digitized broadcast video signals subject to analog-to-digital and digital-to-analog conversion. The network includes a plurality of gateways, each gateway coupled to video signal sources and sink. Video frames transmitted on the network are subject to analog-to-digital and digital-to-analog conversion and compression in an MPEG,encoder/decoder. Each gateway and includes a test pattern generator and test measurement analyzer for in-service testing of the video signals. The test pattern generator inserts a test signal on pre-selected lines (,or,) in a Video Blanking Interval (VBI) and time periods of a video frame. The test signal may be dynamically placed at any location in the frame using concealment techniques The video lines are not seen by television viewers. The test pattern generator and test measurement analyzer are synchronized using vertical integral time code and a trigger packet sent by the transmitting station. The test signals enable both in-service and out-of-service testing to be performed for the entire suite of EIA/TIA 250C standard video tests.

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Haymarket, VA, United States of America

Karl J Kuhn