Electronic Military & Defense magazine was developed for engineers, program managers, project managers, and those involved in the design and development of electronic and electro-optic systems for military, defense, and aerospace applications.
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Tutorial Figure 2: The CROWS (Common Remotely Operated Weapon System) provides the operator with the ability to acquire and engage targets while inside a vehicle. disadvantage. Since the weapon system can only be operated by a single person, only one sector around the vehicle can be viewed at any given time; and when the weapon system is being used to engage one potential threat, it cannot be used to observe any other threat that may appear from a different direction. Another less important disadvantage is the fact that the weapon system has to be mechanically rotated to observe the entire area around the vehicle. This produces extra wear on the gimbal motors, which may cause the weapon system to break during critical action. An alternative solution is to mount a pod of multiple fixed cameras arranged in a circle to provide static 360˚ coverage around the vehicle (Figure 3). By compositing the camera video streams, a single video image can be provided to multiple displays, enabling the vehicle crew to observe the immediate area around the vehicle in different directions simultaneously. This solution has many advantages, especially for vehicles that require retrofit or temporary SA systems. The disadvantage of using a single camera pod is that it is difficult to mount on a vehicle without having a part of the vehicle, or the vehicle's equipment, obscuring some section of coverage. One solution to this problem is to mount the pod on a telescopic pole, but this also presents problems in providing space for the pole and limiting vehicle maneuverability. The ideal solution is to split the cameras up into separate pods and mount them around the periphery of the vehicle, where they will not be obstructed by the vehicle itself. A number of military vehicle integrators are designing SA systems with this in mind. Video Distribution, Processing, And Display Deciding what equipment to use to distribute and display the video data to multiple crew members is guided by the choice of video sensor type and format. In the simplest SA systems, the video can be connected directly from the gimbal-mounted sensor pod to a display, 42 Electronic Military & Defense ■ www.vertmarkets.com/electronics where a single operator can control the pod and view the video. Very little video distribution equipment is required, with minimal cabling between the display and the camera pod. For more complicated systems, with multiple fixed cameras and multiple crew displays to service, video amplification or switches are required to route the incoming video inputs to all the crew displays. Analog systems typically use a video switch system, housed in its own chassis, which has multiple video input and output connections. A similar switch is used for digital Ethernet video, where a gigabit Ethernet switch has multiple 1 Gb or 10 Gb Ethernet ports. Video compositing and display systems also offer a range of different capabilities, from a simple tiled display, where the individual camera video streams are displayed side by side, to more complicated systems that can blend the video streams together to provide a contiguous 360˚ panoramic display (see Figure 4 on next page). Additional features, such as threat detection and video recording, are also becoming common SA requirements. Often, the more simple capabilities, such as video tiling, are built into display screens. The key influencing constraints — along with cost — for every piece of equipment that goes into a military vehicle are size, weight, and power. SA has often been considered of secondary importance to the vehicle's primary fighting role, and therefore SA equipment that is too large, heavy, or power hungry is not attractive. Advances in analog video processing electronics have meant that newer equipment is smaller and lighter and consumes less power than its predecessors. These qualities are very attractive for vehicle use where space and power are limited and weight plays an important role in vehicle range. Cost Inevitably, cost is a significant factor in the choice of SA systems. Analog sensors have been available for a considerable time, and as a result, there is a wide range of rugged, small, relatively low-power, military-proven visual and infrared analog sensors available from a number of different manufacturers. This factor alone continues to make analog sensors Figure 3: Vehicle fitted with a Chess Dynamics Spyder Vista 360T camera pod, allowing uninterrupted 360˚ situational awareness at all times.