Interconnection
Playing a vital role
Miniaturisation is a key requirement for military organisations who are looking for smaller, lighter and more cost effective military kit. Mark Owen looks at some of the key trends and challenges confronting manufacturers
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hroughout the world, military organisations are establishing programmes to modernise their operations to improve situational awareness, flexibility, agility, lethality and survivability. Electronics plays a vital role, and component manufacturers are helping defence equipment OEMs reduce the weight, size and cost of their systems, whilst meeting the ever-increasing performance demands of these programmes. Weight is a particularly vital consideration for dismounted soldiers, typically carrying their own body mass in equipment. Programmes like the US DoD’s “Nett Warrior”, “Soldato Futuro” in Italy, Finland’s “Finnish Warrior” and Australia’s “Land 125”, all involve using electronics to help soldiers know where they are, communicate better with their comrades and commanders and locate and neutralise the enemy.
The burgeoning amount of equipment carried by soldiers today extends to head- up displays, targeting systems, GPS, tactical computers and communications equipment. All of these need power, necessitating a variety of batteries that can make up a third of the weight a soldier carries. All this equipment needs to be connected together enabling sub-systems to communicate through serial buses, wireless personal networks, and out to networks carrying data within the unit and with headquarters. As a result, today’s soldier needs to be fitted with an array of cables, harnesses and connectors. These, too, add weight, occupy space and increase the cost. Furthermore, the networked battlefield demands faster data throughput, greater bandwidth and overall increases in performance. Again, this can be achieved through greater standardisation. The same considerations apply
throughout the defence industry. Size, weight, performance and cost are equally crucial factors for OEMs equipping unmanned vehicles, fighting vehicles, aircraft and naval systems. Interconnect
38 October 2011
standards are even more relevant when it comes to specifying systems that need interoperability – not only between legacy, present and future equipments, but also between different nation’s forces and other branches of the military.
Considerations for OEMs In choosing electronic interconnect, OEMs need to consider and balance a number of key factors, including: the intended operational environment; required level of environmental protection (temperature range, humidity, dust…); the amount of EMI shielding or type of shield termination; size, form-factor and weight limitations; material, coatings and finishes. On top of this, there are the applicable commercial or military standards, which may or may not encompass the preceding constraints. In the past the challenge was compounded by demand to fulfil urgent operational requirements for new equipment. The time taken to develop and approve new military spec components that address these issues is leading some equipment manufacturers to specify commercial off-the-shelf - COTS - devices instead of the full mil spec component. In these increasingly cost- conscious times, military equipment OEMs have leveraged the availability of commercial products to deliver smaller, lighter, non-qualified military connectors to market – and fast.
In many cases, however, COTS components barely meet the requirements of defence OEMs. At best they can provide a solution that works – just. There is the further downside that OEMs are unlikely to find a second source amongst COTS devices that have identically marginal specifications. Proprietary components tick more of the boxes than COTS and provide essentially the same disadvantage of single sourcing. Achieving full military specifications remains the goal.
Miniaturisation In the case of connectors, saving space and Components in Electronics
weight has to be reconciled with the requirement for robustness and reliability across a broad span of environments. Miniaturised connectors need the same performance and standards as their larger mil-standard counterparts, but reducing the size can impact performance. This is particularly important as more and more devices need to be interconnected - and ideally powered from a common source. At AB, product design and development is focusing on high-density terminations that are quick and easy to connect. And, in the present absence of a Standard Mil- Spec connector interface, the new generation of connectors are being designed to be versatile enough to meet a range of different physical and electrical standards.
First new fruits of this effort include a new family of lightweight military connector systems optimised to enhance the portability of rugged field-based communication equipment, especially portable and handheld radios, and personal navigation systems.
These Push-Pull Connectors have been designed to combine lightness with extreme ruggedness and durability. Advantages over similar alternatives include: easier orientation alignment; improved sealing up to 20m depth, when mated or un-mated; variable un-mating force and simplified assembly. Optional built-in Screen-Trap terminations also allow faster assembly of screened cables. An enhanced sealing performance is achieved by implementing multiple O- rings, such as the combination of a dynamic O-ring and additional inter- contact O-rings in the panel-mounted connectors. All connector variants feature colour-coded key location to encourage fast and accurate use in the field. Fixed, free and in-line connector variants
ensure support for differing numerous cable-to-chassis, cable-to-cable and cable- joining applications. A castellated locknut is supplied with the fixed connector to make chassis attachment simpler and more secure; and for cable-to-cable application, scoop-proof contacts in the blind-mateable free connectors prevent bending or shorting of pins during mating.
New materials Manufacturers recognise that the wall thickness of a metal connector shell is a key factor in reducing weight, and are
looking for new alloys and materials to square the circle of rugged yet lightweight construction.
Cable assemblies for defence material also need to meet the growing requirements of an increasingly networked battlefield. Manufacturers are responding with products capable of carrying the latest high-speed data protocols. These feature ruggedized connector styles for extremely harsh environments along with contacts that are designed to simplify the crimping and assembly processes. These smaller, lighter, interconnect components are finding new applications beyond the military. For example mass transit and motorsport OEMs are equally driven by the need to reduce component size and weight to the absolute minimum; and likewise need rugged construction with high reliability and extreme environmental capability. Increasingly, the advantages of military
and aerospace connector design is being used in industrial, automotive and general traction applications, with new modular bayonet-lock connectors that are based on mil-style components. These components accept a variety of multi-pole contacts including quadrax contact modules to enable reliable signal and high-speed data interconnects up to 100Mbit/s. Any combination of co-ax, twin-ax, tri-ax or quadrax modules can be specified, delivering a highly versatile connector system capable of consolidating up to seven high-speed Ethernet connections or many combinations of signal and data links. Retention force of at least 200N ensures secure connections when exposed to large mechanical stresses. Simultaneously, components such as push-pull connectors designed for non- military service are proving their worth in the armed forces. Expanding the market in both directions helps to drive costs down: indeed, manufacturers are working closely with suppliers and customers throughout the supplier chain to ensure widest availability at more competitive prices. With initiatives like this, security of supply and predictable cost are proving the essential ingredient in the military’s size, weight and power reduction programmes.
TT electronics |
www.ttelectronics.com Mark Owen, Product Manager, TT electronics AB Connectors
www.cieonline.co.uk
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