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From Analog to Digital Video in Defense Systems – How CoaXPress makes it possible

Posted by Gretchen Alper on Thu, Sep 8, 2011

Traditional outdoor (traffic/surveillance/defense) applications have been well served for decades by the analog camera that interfaces the image processing unit viaRugged Camera Coax a coax cable. This combination has provided a simple, robust connection with the image quality and features needed at the time.  Modern outdoor applications, however, are far more complex and demanding. 

 

The changes from previous generation systems can include:

  • From Analog to Digital cameras (for better quality images and useful data)
  • From VGA to 1080p or even Larger fields of view (for wide or long range viewing)
  • From 30 frames per second to 60 fps or higher (to track faster moving objects)
  • Camera communication (for adapting systems to a broad range of uses and conditions)
  • Tight synchronization with detection and fire and control (for integration with control systems)

Operation under Rough Conditions

Severe or restrictive environments found in many of the outdoor markets not only require demanding specifications of the camera and computers but can challenge the capabilities of the video-interface as well.  Many system integrators and manufacturers need an interface that can address the following specifications:

  • High bandwidth (greater than 1 Gigabit per second (Gbps))
  • Long cable runs (between 10 and 50 meters)
  • Fishing cables through tubes or arms
  • Flexing of the cables
  • Small spaces (limited bend radius, smaller connector size, connector options)
  • Proximity to other cables (increased cable “cross-talk”)
  • Mechanical stress on cables and connectors
  • Signal and power over slip-rings for turrets and movable sub-systems
  • Harsh environmental conditions (EMI, temperature, chemical)

Many of these challenges are addressed by using coaxial cables. Although this cable is almost 50 years old, it is still capable of transmitting a lot of data, such as high quality digital images, while maintaining its robust characteristics.

Some emerging interfaces offering the required specification are based on coaxial cables, like CoaXPress. The CoaXPress interface was designed from conception to be robust and reliable in a wide range of conditions.  Considerations include the physical layer (coax cable and connector) which is readily available in large and small diameter, military, chemical/temperature resistant, high flex, double shielded and double core formats.  The standard also incorporates electronic and communication systems to maximize reliability.  These include an equalizer to “tune” the hardware to the selected cable (wave guide) maintaining high bandwidth over different cable types, lengths, and conditions.  The standard also incorporates CRC (cyclical redundancy check) to prevent data errors, and plug-and-play ability to reset the protocol automatically after connection is lost.

Move from analog to digital over slip ringsCoax rotary joints slipring coaxpress

There is a subtle difference between CoaXPress and other interfaces, like HD-SDI or 3G-SGI, that gives it another unique advantage.  It is currently the only interface that provides 100% functionality and power over a single coax connection.  This enables integration into challenging systems, such as rotating turrets with slip rings.  Slip rings were commonly used in analog environments and have now become even more prevalent with moving electro-optical systems on vehicles for better observation and tracking capabilities.   See CoaXPress in a slip ring.

 

This enables a “360 degree” imaging system using one camera instead of 3, 4 or 8… or a periscope optic for a low profile and to protect the camera, and many more possibilities. 

There are many, excellent camera interfaces available.  The basic requirements of a system will quickly direct an integrator to the right one.  Advanced camera integrations with demanding or unique requirements can look to CoaXPress as a solid and capable solution.

For a comprehensive discussion and comparison of camera interfaces:describe the image

Special contribution by Brian Kimball, Adimec Product Support Engineer   


Topics: Interface Technology

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