AR# 70693

SMPTE UHD-SDI RX Subsystem v1.0 - Why is the rx_mode always at 3'b101 for 12G-SDI, even when the fractional line rate is received, when targeting UltraScale or UltraScale+ devices?

Description

Why is the rx_mode always at 3'b101 for 12G-SDI, even when the fractional line rate is received, when targeting UltraScale or UltraScale+ devices?

Why is rx_mode always shown as 3b101 for both the 12-G SDI integer line rate and 12-G SDI fractional line rate?

Solution

This is expected behavior when targeting UltraScale and UltraScale+ devices.

This is because in most conditions the transceiver is able to detect both the 12G-SDI integer line rate and the fractional line rate with a single reference clock.

(Note: Users should use both reference clocks to guarantee that that the GT CDR does operate within spec and will be able to lock in all conditions.)


Because the SMPTE UHD-SDI RX Subsystem is able to find the TRS and perform successful alignment with the 12G-SDI integer line rate mode, it is not moving to scan the 12-G SDI fractional line rate mode.

In this case the rx_mode is set as 3b101 even though 12-G SDI fractional line rate data is received. 

The rx_bit_rate generated by the UHD-SDI Compact GT Wrapper correctly reflects the 12G-SDI integer vs fractional line rates.


You should monitor the user rx_mode output and rx_bit_rate to determine if the incoming signal is 12G-SDI integer or fractional line rate.

Linked Answer Records

Master Answer Records

Answer Number Answer Title Version Found Version Resolved
68766 SMPTE UHD-SDI RX Subsystem - Release Notes and Known Issues for the Vivado 2017.3 tool and later versions N/A N/A
AR# 70693
Date 05/02/2018
Status Active
Type General Article
IP