Baseband Video Processing with Dummy Data for CDR Stability
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Solution Overview
Problem
Existing data transmission systems experience interruptions and black images due to jitter-fluctuations when transmitting baseband video data over unstable networks, causing clock data recovery (CDR) to unlock in reception devices, necessitating link retraining and prolonged blackouts.
Innovation Solution
A data processing device with a clock data recovery unit that extracts and processes data based on a predetermined transmission path, outputting dummy data during jitter-fluctuations to maintain clock extraction and prevent CDR unlocking, thereby avoiding link training and blackouts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If baseband video data is transmitted via an unstable network path, then transmission flexibility and adaptability are improved, but jitter-fluctuation causes CDR unlocking and link interruption
Solution Approach 1:
The transmitting device performs preliminary action by generating dummy data in advance and storing it in a buffer before actual transmission. When jitter-fluctuation occurs during network transmission, the receiver can immediately switch to using the pre-stored dummy data to maintain continuous clock extraction, preventing CDR unlocking and avoiding the need for link retraining
Solution Approach 2:
Dummy data acts as an intermediary element between the unstable network transmission and the sensitive CDR circuit. This intermediary dummy data absorbs the shock of transmission instability, providing a stable clock signal source that prevents the CDR from unlocking during jitter events, thus mediating between the unstable input and the stability requirement of the receiver
2Reliability
If link training is performed to restore connection after jitter-fluctuation, then link reliability is improved, but transmission time is increased due to black image periods
Solution Approach 1:
The system performs preliminary action by pre-generating and buffering dummy data before jitter events occur. This allows the receiver to immediately switch to dummy data for continuous clock extraction when jitter occurs, eliminating the need for time-consuming link training procedures and preventing black image periods during recovery
3Productivity
If continuous data transmission is maintained during jitter-fluctuation, then productivity is improved, but display disturbance increases causing user discomfort
Solution Approach 1:
Dummy data serves as an intermediary that shields the display system from the harmful effects of jitter-fluctuation. By inserting this stable dummy data into the transmission stream during jitter events, the system maintains continuous data flow for productivity while the dummy data's stable characteristics prevent display disturbances that would cause user discomfort
Data Source
AI summary
The CDR in a reception device (sink device) at a subsequent stage can be prevented from being unlocked even when jitter-fluctuation occurs due to transmission via an unstable transmission path such as a network. The clock data recovery unit extracts a clock and data on the basis of the baseband video data of a first format corresponding to a predetermined transmission path input from the predetermined transmission path. The extracted data is processed by the processing unit on the basis of the extracted clock. In this case, in a case where the occurrence of the jitter-fluctuation is detected, dummy data capable of clock extraction at the subsequent stage is output. For example, the processing unit outputs baseband video data in a second format, and the baseband video data in the second format is baseband video data corresponding to a predetermined wired interface.