3G-SDI Signal Quality & Compliance Testing

The use and distribution of 3G-SDI within a broadcast environment has
enormous logistical advantages, but along with these advantages come some
real challenges for both engineers and manufacturers who may be familiar with
more conventional SD 270MB or HD 1.5GB SDI systems. 3G-SDI is attractive to
broadcasters looking to move from 720p or 1080i based systems to full 1080p 50
or 59.94 for live production. It’s also used as part of quad 1080p as part of a UHD
system.

One advantage is the ability to send numerous different video broadcast,
production and digital cinema formats down the same single wire, but the impact
of this on engineers who have to understand all of the complexities of the SMPTE
424M, 425A (3G-A) and 425B (3G-B) when connecting and routing signals is
not insignificant. Manufacturers too have the challenge of designing broadcast
equipment to test all of the possible format combinations of HD-SDI, Dual Link
HD, 2K, 3D stereoscopic 2K; colour spaces of YCrCb, RGB and XYZ; sampling
methods such as 4:2:2, 4:4:4; specific data mappings for each format; not to
mention the added complexity of Alpha channels.

The challenges of 3G-SDI use also have an impact on signal distribution,
signal routing, switching, editing and grading. Two significant areas to take into
account when using 3G-SDI are signal quality, which if out of specification will
have a dramatic impact on the integrity of the data, and the ability of broadcast
equipment to transparently process the numerous video formats combinations
that may appear on the end of the cable.