This application note describes how to implement the digital line length tracking (DLST) function using the AD9850 and AD9852 devices. The DLST function is used to compensate for noise-induced errors in the line length of digital video signals. This compensation improves the accuracy of the video image.
This document describes Adaptive Digital Line Length Tracking (ADLLT), a technology used to decode and restore the correct time base for nonstandard input video sources. It addresses challenges such as noise-induced time-base inaccuracies and VCR-induced errors that cause synchronization issues and image artifacts like top curl.
The note details how Analog Devices (ADI) decoders utilize synchronous detection, extraction blocks, resamplers, and FIFO management to filter noise and ensure correct synchronization extraction. It explains the line locked time-base correction method that delivers a fixed number of samples per line, smoothing out short-term jitter variations.
It addresses challenges in decoding and restoring a correct time base to nonstandard input video sources.
All video and synchronization is lost, resulting in a flat dc output for that duration.
ADI decoders use 54 MHz fixed frequency sampling to digitize the input video.