Extracting digital data from a bus and multiplexing it with a video signal

摘要

A television video data instrumentation recording system is coupled to a Bus Monitor/Video Encoder to incorporate a digital data recording capability within the normal video signal recording process while allowing for later digital data recovery during video playback. The digital data is acquired from a device addressable serial data bus which is normally an asynchronously polled system for exchanging data messages between a bus master device and multiple slave devices where each slave device has a unique device identification code for its messages. Data acquisition is a passive function (relative to the data bus) involving the hardward programmable selection of messages of interest (based on the message device code) and the software programmable deletion of messages that contain no data of interest. Another feature of data acquisition is that a time reference for time-of-acquisition is appended to the acquired messages of interest. This approach also intercepts the video signal between the television source and the recording system, programmably assembles the acquired data messages into recording data blocks synchronized to the video signal, and performs a formatted serial encoding conversion of the data blocks into a video signal. Once recorded, the video signal can be played back with programmably selected portions of the video subjected to a decoding conversion that recovers the formatting information and data such that the original acquired data messages (and time tag) can be reconstructed with minimum data loss due to recovery errors.