Choosing the Right Video Interface for Military Vision Systems
Executive Summary
This paper discusses how GigE Vision® video interfaces — the technology used to transfer data from a camera or image sensor to a mission computer or display — help designers reduce the cost and complexity of military imaging systems, while also improving usability and increasing intelligence for end-users.
The paper begins with a detailed review of video connectivity approaches commonly used in military imaging systems, followed by an overview on the GigE Vision standard. With this background, the design, cost, and performance benefits that can be achieved when employing GigE Vision-compliant video interfaces in a vetronics retrofit upgrade project are outlined.
Introduction
Vision systems are playing an increasingly important role on the battlefield. In manned and unmanned applications, sophisticated networks of cameras, sensors, software, and processing platforms must operate seamlessly and in real-time to provide a wider area of view, or insight into areas beyond the scope of normal human vision. These imaging systems help keep troops out of direct harm, and enhance their performance by improving surveillance, intelligence, and situational awareness.
Behind the complex array of cameras and sensors, advanced hardware and software components that comprise the video interface must transfer high-resolution video from imaging sources to display panels and computers used for processing and analysis. In mission-critical military imaging applications, it’s imperative that video is delivered in real-time, with low, consistent “glass-to-glass” latency (or delay). In a closed hatch driving (CHD) application, for example, there can be no perceived transmission delay between the cameras and sensors mounted on the vehicle and the navigation display panels.
The video interface is a small part of the overall imaging system, but it has a disproportionately large impact on the performance, usability, cost, and scalability of the final product. Specific to military imaging design, choosing the right video interface helps meet size, weight, and power (SWaP) objectives and purchasing specifications that prescribe the use of commercial off-the-shelf (COTS) products. The video interface design choice will also impact a manufacturer’s ability to retain costly existing infrastructure in a retrofit upgrade, and should provide a future-proof solution that is easily scalable as new imaging and sensing technologies are introduced.
Considering these performance and design challenges, this paper presents GigE Vision-compliant video interfaces as the cornerstone of military imaging system design.
Video Interface Evolution
One of the most significant technical advances helping increase the tactical advantages and safety of combat troops is the continuing evolution of digital vision sensors. The all-digital image streams generated by advanced sensors can be fed directly into modern in-vehicle processing applications, improving the precision of surveillance and targeting tasks and making it possible to identify an object or person miles away, even at night.
New-generation vision sensors create a substantial opportunity to increase surveillance and intelligence, but also pose performance challenges related to video transmission. Behind the crisp, high-definition images the sensors produce are millions of pixels of digital data. To fully leverage the potential of this data in local situational awareness (LSA) and CHD systems, it must be distributed, displayed, and processed in real time with ultra-high reliability. In many applications, feeds from new digital sources must also be seamlessly blended with video from existing analog cameras and distributed or archived.
Military imaging system designers have often relied on video interfaces based on proprietary designs, or adapted existing legacy standards, to transmit video and images from a camera or sensor to a mission computer or display. However, these approaches limit component choice, increase costs, and result in more complex systems.
With a custom solution, designers often underestimate the time, expense, and technical challenges required to meet strict real-time video transmission performance requirements. Designers must also consider the comprehensive standards published by global defense organizations that outline the engineering and technical requirements for military applications. This includes the U.S. Army’s Vehicular Integration for C4ISR/EW Interoperability (VICTORY) and the European GVA (General Vehicle Architecture) initiatives that guide vehicle network interoperability requirements and encourage the use of COTS open-system standards.
Existing video interface standards, including analog and Camera Link®, have also been adapted for military imaging applications. As imaging systems perform more complex tasks, and end-users seek easier-to-use, lower cost solutions, the limitations posed by these legacy interfaces become more apparent.
Each of these interfaces requires a dedicated connection between the cameras and endpoint, whether that is a computer for image analysis or a display panel for observation. In applications where images are viewed across multiple screens or displays, the cabling required for these umbilical connections becomes costly, complex, and difficult to manage and scale.
Moreover, to capture data these interfaces need a PCIe frame grabber at each endpoint. This requirement limits the types of computers that can be used, drives up component costs, and increases complexity. End-users are also locked in to the frame grabber vendor for support, relying on them to write drivers for specific operating systems and processing architectures. Expensive switching is also required to support real-time video networking.
Considering the limitations of proprietary and legacy video interfaces, it is not surprising that military imaging systems designers are increasingly turning to products based on proven standards developed for the machine vision industry.
Comparison of Vision Standards
While a bin-picking robot on a factory floor and a combat vehicle patrolling a battlefield may seem worlds removed, designers of these imaging systems often face the same real-time performance requirements and cost-reduction objectives.
In the early factory automation market, video interfaces were typically based on proprietary solutions, or existing telecommunications and consumer electronics standards were adapted for machine vision applications. But as imaging applications moved from research labs onto manufacturing floors, the vision industry recognized the limitations of these approaches and developed standards regulating the transport mechanism, video format, and control mechanisms. The consistent goal of these evolving standards is to help manufacturers simplify design and lower system costs, while making it easier for end-users to install, upgrade, and maintain imaging system.
Table 1 compares key attributes of three digital video connectivity standards — Camera Link, CoaXPress, and GigE Vision — that manufacturers often consider for military imaging applications.
Table 1: Key attributes of video connectivity solutions
Camera Link is a digital serial interface standard introduced in 2000 by the AIA (Automated Imaging Association). It transports imaging data at high rates over direct links of 10 meters or less. Cable extenders can lengthen the short reach of Camera Link connections, but at a significant cost. A PCIe frame grabber is required at each endpoint to capture image data.
Camera Link is also limited by its dependence on point-to-point topologies. Cameras are tethered to the frame grabbers at the end-point, restricting system design options. Many vendors offer frame grabbers that support more than one camera, but the resultant ‘star’ deployments do not offer the flexibility and scalability of a true networked topology. Camera Link HS, a high-speed version of Camera Link released in 2012, is limited by short cable reach and has gained narrow industry adoption.
The second candidate, CoaXPress, is a standard for a point-to-point, asymmetrical serial communication that runs over coaxial cable. This standard was introduced in 2009 by a small industry consortium and approved by the Japan Industrial Imaging Association (JIIA) in December 2010.
CoaXPress offers longer reach than Camera Link, but as it is supported by only a small group of vendors it is not widely deployed. CoaXPress has some advantages in its speed, reach, and straightforward coaxial cabling, but like the other non-Ethernet based standards has no networking capability. It was designed primarily to address some large existing coax installations, and as a consequence, has gained only narrow industry acceptance. Speeds comparable with 10 Gigabit Ethernet are only attainable by using using expensive multi-core and active cables, and over significantly shorter distances.
GigE Vision, in comparison, is based on the mature Ethernet standard. Deployed in most local area networks, Ethernet is supported by a low-cost, well-understood, and widely available infrastructure from multiple vendors. Recognizing the potential for Ethernet in vision applications, the AIA launched the GigE Vision standard in 2006. Today, GigE Vision is the most widely deployed video interface standard for industrial applications and is quickly gaining traction in the military, security, medical, and transportation markets.
With the GigE Vision standard — encompassing GigE, 10 GigE, and wireless — imaging data is transmitted by wire or wirelessly to the Ethernet port on a computing platform. With no need for a PCIe frame grabber, video can be displayed on any type of computer, including ruggedized laptops, tablets, single-board computers, and embedded platforms. Each generation of the Gigabit Ethernet and GigE Vision standards use the same frame format, ensuring backward compatibility and permitting system upgrades without sacrificing equipment already in place.
The long reach of GigE cables — up to 100 meters between network nodes over standard, low-cost Cat 5/6 copper cabling and even greater distances using inexpensive fiber cabling — supports fully flexible system design. Power over Ethernet (PoE) enables “one-cable” installations to deployment by freeing systems from hard-wired power requirements for cameras. In shorter-reach applications, wireless GigE Vision video interfaces eliminate cabling altogether, thus reducing bill of material, setup, and maintenance costs.
When the GigE Vision standard was introduced, it was valued primarily for its long-reach cabling in umbilical camera-to-computer connections. Today, designers are using Ethernet’s networking flexibility to build real-time switched video networks that allow one camera to send video to multiple endpoints, multiple cameras to send video to one endpoint, or combinations of the two. This means video can be easily distributed to multiple displays, to users in different locations, combined with other image feeds, and sent to remote recording units — all without changing hardware or software. Since Ethernet is scalable, it supports meshed network configurations that easily accommodate different data rates and the addition of new processing nodes, displays, and sensors.
Ethernet has obvious and significant advantages over Camera Link and CoaXPress. With its unique combination of networking, throughput, flexibility, distance, and scalability, GigE Vision is the optimal choice for video connectivity in military imaging applications.
As the GigE Vision standard gains wider adoption across multiple markets, an increasing number of video interface products are now available as off-the-shelf solutions. For retrofit projects, external frame grabbers make it straightforward to convert feeds from existing cameras into more manageable GigE Vision-compliant video. With embedded hardware solutions, manufacturers can easily integrate GigE Vision video connectivity directly into cameras and imaging systems.
GigE Vision Video Interfaces in an LSA Imaging System
The Ethernet platform and GigE Vision standard provide an excellent framework for building high-performance networked video connectivity systems for LSA applications, particularly as designers seek new approaches to modernize existing systems, lower costs, and meet SWaP objectives.
LSA systems often rely on analog and digital cameras and image sensors to enable vehicle drivers and crew members to navigate, conduct surveillance, and detect and identify threats. Traditionally, image data has been streamed directly to processing platforms and panel displays using proprietary or legacy analog interfaces. These point-to-point connections are costly, complex, difficult to manage, and expensive to scale.
Ethernet is a natural choice for video transmission in LSA systems due to its networking capabilities, support for different computing platforms, and light-weight, off-the-shelf cabling. As illustrated in Figure 2, by employing GigE Vision-compliant video interfaces, designers can easily upgrade vision systems for military ground vehicles to integrate new digital cameras and image sensors, existing high-value analog cameras, displays, and processing computers into a single, all-digital, real-time video network.
In the LSA application, real-time video from analog and digital cameras and sensors is transmitted to display panels for crew members to navigate the windowless vehicle and survey surroundings. Video from analog cameras is converted to GigE Vision at the source by standard-compliant external frame grabbers and streamed uncompressed over the multicast Ethernet network to displays and processing equipment at various points within the vehicle. Video, control data, and power are transmitted over the single cable; lowering component costs, simplifying installation and maintenance, and reducing “cable clutter” in the vehicle.
Figure 2: GigE Vision-compliant video interfaces allow designers to easily upgrade vision systems by integrating digital cameras and image sensors, analog cameras, displays, and processing computers into a real-time video network
All computers used for processing and mission control connect to the network via their standard Ethernet port, eliminating the need for a computing platform with an available peripheral card slot. This means system designers can employ ruggedized laptops, embedded PCs, or single-board computers for image analysis and control to help lower costs, improve reliability, and meet SWaP objectives. At display panels, external frame grabbers receive GigE Vision video data and output it in real time with low, consistent latency over an HDMI/DVI interface.
Taking advantage of the multicasting capabilities of GigE Vision, video can be transmitted to an onboard transcoder gateway. The transcoder preserves the high-quality GigE Vision video for processing and analysis, while automatically converting the images into the H.264 compression format. The compressed video can then be efficiently transmitted over a wireless connection using real-time streaming protocol (RTSP) to a command center, other vehicles, or battlefield troops who can view the video on tablets. The video can also be archived to a USB-attached storage device.
With all devices connected to a common infrastructure and straightforward network switching, multiple streams of video can be transmitted to any combination of mission computers and displays. Troops can decide “on the fly” which video streams they need to see, without any changes to cabling or software configurations, or use the on-board mission computer to combine images for use by others in the vehicle.
For example, the video feed from a visible light camera can be converted to GigE and blended with the video feed from a GigE Vision infra-red sensor to give crew members more detail on a region of interest. As illustrated in Figure 3, embedded hardware converts the image stream from an analog camera into GigE Vision-compliant video. Alternatively, the video feed from an existing analog camera can be converted into GigE Vision video using an external frame grabber.
Beyond LSA systems, GigE Vision-compliant video interfaces are ideal solutions for vision systems used in sighting, threat detection, weapons targeting, and surveillance applications in naval vessels, manned and unmanned airframes, and standalone systems for persistent surveillance.
Figure 3: Embedded hardware allow manufacturers to integrate GigE Vision video connectivity into existing designs, enabling all-digital video streams that can be easily networked and multicast to end-users
Clear Design Choice for Military Imaging
The video interface is a design cornerstone of all vision and imaging systems. As the machine vision market has matured, GigE Vision has emerged as the dominant standard. This has helped drive the development of standard-compliant COTS products — including external frame grabbers, embedded hardware, software, and cameras — that are field-proven in rugged applications.
For military applications, GigE Vision-compliant video interfaces are enabling new generations of imaging systems that cost less, weigh less, and are easier to use than systems based on legacy point-to-point standards or custom solutions. This standard is widely supported by equipment vendors, making it straightforward for vision system manufacturers to source products that interoperate with existing infrastructure. Moreover, GigE Vision helps manufacturers meet specific military standards focusing on vehicle network interoperability and COTS open-system standards, while ensuring future scalability.
About Pleora
Pleora Technologies invented high-performance frame grabbers and embedded hardware for the delivery of video over Gigabit Ethernet, and leads the market in video interfaces for USB 3.0 and wireless. With this spirit of innovation, Pleora engineers reliable video interfaces for system manufacturers and camera companies serving the military, medical, and industrial automation sectors. Pleora provides end-to-end solutions that shorten time-to-market, reduce risk, and lower costs. We partner with customers and tailor our products to individual needs.
Pleora’s rich portfolio of solution elements delivers a robust, end-to-end platform that is compliant with the GigE Vision standard and can be tailored to meet the networked video requirements for both the retrofit of existing military imaging systems and the design of new ones.
For retrofit programs, Pleora’s iPORT External Frame Grabbers can be used to efficiently convert feeds from existing video sources into GigE Vision compliant video streams. The streams can then be incorporated into a common, real-time GigE Vision framework that is all-digital, all-networked, and manageable.
This approach allows designers and integrators to preserve legacy cameras and sensors, while delivering a scalable Ethernet backbone that is backward-compatible with older technology and enables the introduction of advanced digital sensor technologies.
For new platforms, the iPORT Embedded Video Interfaces can be built directly into new-generation high-resolution cameras, making them GigE Vision compatible from the start. Pleora is working already with a number of camera manufacturers and military systems integrators on projects of this nature.
Integration can be accomplished by adding an iPORT Embedded Video Interface to the back end of the camera, or by integrating Pleora’s IP core into the camera’s FPGA and a digital sensor directly onto a processing board, thus reducing component count and simplifying the overall hardware design.
In all scenarios, mission computers can be equipped with Pleora’s eBUS SDK, enabling video from a GigE Vision compliant link to stream in real-time into system memory, without the need for a frame grabber. With this software suite, designers can rapidly prototype and deploy production-ready software to support video transmission over GigE, 10 GigE, USB 3.0, and wireless using the same application programming interface (API).
Find out more at www.pleora.com
