The Wide-Field Dynamic Range (WFDR) camera is a high-sensitivity, wide-field-of-regard sensor of importance to future military surveillance and survivability systems. It is intended to be used in harsh, noisy military platforms with multiple camera streams simultaneously gathered. By developing a Gigabit Ethernet (GigE) video transport solution for multiple cameras with low latency and high data reliability, a flexible processing architecture will be developed that allows optimization of processor throughput for real-time imaging in defense applications.
The following innovative features of this concept include:
- Digital Data Distribution — The goal was a 200x reduction in data noise, insulating the data from interference in electrically noisy military platforms. Prior military systems make use of analog point-to-point designs: a nominal 8-bit data acquisition of analog transmissions at best had produced six effective bits of analog signal. Using direct digital distribution achieves at least 14 effective bits with a 16-bit resolution.
- Multiplexed Control and Synchronization — Multiple video data streams can be sequenced, allowing a single-board computer to gather data from multiple sensors as the host is ready for data, while the sensors operate independently in parallel. The sensors provide metadata in the digital stream, allowing knowledge of precise timing of frame acquisition. This allows images to be synchronized with platform motion.
- Embedded Design — Design for use in real-time systems that meet deterministic schedules for host applications. Current analog-based systems have to estimate latency for when a commanded change to a camera setting has actually taken place. An analog frame grabber runs open loop and continuously grabs frames regardless of their generation. A digital network allows the host to initiate exposures on command, as well as to know, with certainty, that a commanded change is in effect and data is available.
- Military Ruggedization — Operation of surveillance video in harsh military environments, to include temperature extremes. A reliable iris drive, with precise index sensing, allows the camera to be used under both day and night conditions.
The camera was essentially redesigned to develop custom electrical, mechanical, and thermal solutions to the new interface. There are only five boards at the front — CCD, ADC, FPGA, USB, and CLINK — with the power converter, power regulator, and GigE boards at the rear of the camera, heat sunk to the case connected to the main stack via a self-aligning connector.
The digital WFDR provides the desired high-resolution, high- speed imaging capability. Due to the possibility of setting the cam- era to long integration times and high EM gain, as well as to short integration times with closed iris, the camera is capable of surveil- lance applications from the darkest night to the brightest day.
The camera is capable of rapid switching between different set- tings to grab frames. While the manufacturer’s requirements allow 100 ms for the camera to reach a new operating condition, up-changing exposure time or EM gain, it appears that both these transitions occur much faster, enabling the camera to produce images at a new gain state at its maximum rate of over 30 Hz.
This work was done by Lon Sunshine and Peter van Ham of BAE Systems Technology. For more information, download the Technical Support Package (free white paper) at www.defensetechbriefs.com/tsp under the Physical Sciences category. DARPA-0009
This Brief includes a Technical Support Package (TSP).
GigE Advanced Imaging Sensor
(reference DARPA-0009) is currently available for download from the TSP library.
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