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Pros and Cons HD-SDI/3G-SDI for Global Security

Posted by Gretchen Alper on Wed, Apr 10, 2013

The HD-SDI video interface standard was developed for television broadcasting, but it can be advantageous in global security applications such as high-end surveillance or unmanned systems, allowing simple designs or upgrades with full HD cameras.

Serial digital interface (SDI) is a family of video interfaces standardized by SMPTE (The Society of Motion Picture and Television Engineers).  High-definition serial digital interface (HD-SDI), and 3G-SDI are related standards offering nominal data rates of 1.485 Gbit/s (dual link) and 2.970 Gbit/s serial link, respectively.

These standards are used for transmission of uncompressed, unencrypted digital video signals within television facilities.  There are coaxial and fiber optic options.   Source: [http://en.wikipedia.org/wiki/Serial_digital_interface]

Versions / Standards

Standard

Name

Bitrates

Example Video Formats

SMPTE 259M

SD-SDI

270 Mbit/s, 360 Mbit/s, 143 Mbit/s, and 177 Mbit/s

480i, 576i

SMPTE 344M

ED-SDI

540 Mbit/s

480p, 576p

SMPTE 292M

HD-SDI

1.485 Gbit/s, and 1.485/1.001 Gbit/s

720p, 1080i

SMPTE 372M

Dual Link HD-SDI

2.970 Gbit/s, and 2.970/1.001 Gbit/s

1080p

SMPTE 424M

3G-SDI

2.970 Gbit/s, and 2.970/1.001 Gbit/s

1080p

Source:  Wikipedia (http://en.wikipedia.org/wiki/Serial_digital_interface)

Some global security applications are similar to broadcast in that the end user is a display device (as compared to machine vision where a computer is the “consumer” detecting grey level variations, etc.).  The images are used for viewing. 

Many analog systems were developed based on the previous generation SDI standards.  HD-SDI and now 3G-SDI allows for an upgrade to full HD digital cameras at fast frame rates.  For instance, the Adimec TMX6-DHD/SDI offers full color HD images at 30+ fps. 

Here are some of the pros and cons of the HD-SDI interface in global security applications:

 

Pros

  • GigE Vision, Camera Link, USB3 Vision, CoaXPress, etc. all require a computer in between the camera and the monitor where as HD-SDI provides a direct connection between the camera and the display
  • Many existing displays in the field/legacy systems can still be used with higher resolution cameras now available (you will need to verify compatibility).
  • It is a true plug and play solution, so it can be used to create a simple surveillance system
  • Long distance cable lengths (100m+)

 

Cons

  • It is a purpose specific interface so expensive supporting equipment (monitors) are required (not inexpensive consumer products)
  • The quality of the display may be more than what is required (color, saturation, etc. are broadcast level)
  • From a camera perspective, there is no provision in the standard for camera control (one-directional) so the user can’t change the camera settings or send power over it, etc. A separate connector is needed for camera control.
  • The resolution and frame speeds must be preset (lose flexibility).
  • There is no monochrome definition as the standard is written for color cameras (there are some workarounds)

 

 

For more information on other camera interface options, check out our free interface comparison eBook:

machine-vision-interface-comparison

 

Topics: Interface Technology

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