GS2960A Datasheet, PDF (31/99 Pages) Gennum Corporation – Ancillary data extraction

4.7.2 Signal Interruption
The device tolerates a signal interruption of up to 10μs without unlocking, as long as no
TRS words are deleted by this interruption. If a signal interruption of greater than 10μs
is detected, the lock detection algorithm may lose the current data rate, and LOCKED
will de-assert until the data rate is re-acquired by the lock detection block.
4.8 SMPTE Functionality
4.8.1 Descrambling and Word Alignment
The GS2960A performs NRZI to NRZ decoding and data descrambling according to
SMPTE 424M/SMPTE 292/SMPTE 259M-C and word aligns the data to TRS sync words.
When operating in Manual mode (AUTO/MAN bit in the host interface is set LOW), the
device only carries out SMPTE decoding, descrambling and word alignment when the
SMPTE_BYPASS pin is set HIGH and the DVB_ASI pin is set LOW.
When operating in Auto mode (AUTO/MAN bit in the host interface is set HIGH), the
GS2960A carries out descrambling and word alignment to enable the detection of TRS
sync words. When two consecutive valid TRS words (SAV and EAV), with the same bit
alignment have been detected, the device word-aligns the data to the TRS ID words.
TRS ID word detection is a continuous process. The device remains in SMPTE mode until
TRS ID words fail to be detected.
NOTE 1: Both 8-bit and 10-bit TRS headers are identified by the device.
NOTE 2: In 3G Level B mode, the device only supports Data Stream 1 and Data Stream
2 having the same bit width (example: both data streams contain 8-bit data, or both data
streams contain 10-bit data). If the bit widths between the two data streams are different,
the GS2960A cannot word align the input stream, and remains in Data-Through mode.
GS2960A 3Gb/s, HD, SD SDI Receiver
Data Sheet
54384 - 2
September 2012
31 of 99