SYSTEM DEVELOPMENT Open Standards for Navy Modernization
3G-SDI’s Many Advantages Serve Defense Video/Display Needs Video interface technologies tend to advance so fast it’s hard to keep pace. Military system developers should examine the benefits of moving to 3G-SDI. John Payne, Product Manager Chris Fadeley, Senior Software Engineer EIZO Rugged Solutions
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ne of the most daunting tasks for engineers is how to employ existing and proven technology while hopefully future proofing systems for technology upgrades. This is of critical importance to systems in the military market with air and naval systems having life cycles that can be in excess of 35 years. The problem is even more acute in deploying video imaging and display technology. Video image resolutions have been steadily increasing in size based on improving sensor/camera resolutions and increasing quality and resolution of LCD panels. Just in the past few years the video broadcast industry has moved from PAL (720x576 Interlaced) to HD720p60 (1280x720 Progressive) and then to HD1080p30 (1920x1080 Progressive) and future formats of WQHD (2560x1440) and UHD-1 (3840x2160) are on the near horizon. The bandwidth required to support these formats pose a challenge for selecting an interface standard since the size of the data is becoming exponentially larger. Analog standards like VGA are willfully inadequate for today’s higher resolutions. Digital video is the only choice, but which standard is the optimum choice? DVI, HDMI, DisplayPort and SDI (Serial Digital Interface) are the typical options when handling a digital video signal and many monitors support multiple input types. However, there are clear tradeoffs between each of them. 30
COTS Journal | September 2016
Interface
Cable Length
Audio
Number of Pins
Year Designed
3G-SGI
100 m
Yes
2
2006
HDMI
10 m
Yes
19
2002
Display Port
3m
Yes
20
2006
DVI-D
3m
No
24
1999
Figure 1 Multiple factors to compare amongst video interfaces—including supported cable length, resolution and audio integration.
Back to Basics To select the best solution, it is necessary to go back to the basics. Military systems require reliability, simplicity, expandability, and mature standards based technology. Looking at DVI, HDMI, and DisplayPort – all these are digital standards employing some form of SERDES technology. However, they all require multiple channels (connections) of serialized data. Thinner (lesser number of connections) cables are much preferred since cable thickness can drive the flexibility, weight, length, and ease of installation. Besides, to ensure video quality, HDMI usually can have a maximum length of 20 meters and DVI-DL (Dual Link) and DisplayPort can both be approximately 4.5 meters.
Resolution and audio integration are also important considerations. DVI-DL supports resolutions up to 2560x1600, but does not support audio. HDMI_2.0 and DisplayPort V1.2 can support 3820x2160 at 60 frames per second and support audio. Figure 1 shows a summary those different interfaces. While HDMI, DVI, and DisplayPort are more widely found and familiar in the consumer space, SDI is a more widely accepted interface standard for video distribution. It is a mature standard that was first adopted by the commercial video broadcast community but in recent years it has been incorporated in a number of consumer devices such as low cost HD video cameras. This is advantageous because COTS suppliers will