According to the Defense Systems Management College (DSMC), Program Sustainment is defined as an activity to meet the operational and support requirements of a program in a cost effective manner. Program Sustainment emphasizes system availability, maintenance, and system upgrades, but in the case of the AN/ARS-6(V) being re-designed at the EMPF, this includes increases in functional capabilities, manufacturability, and packaging as well.

The AN/ARS-6(V) Personnel Locator System (PLS) is the airborne radio that communicates with the PRC-112 and other handheld survival radios during CSAR (Combat Search And Rescue) operations. They are used by the US Army, Navy, Air Force, National Guard, Coast Guard and NATO, providing directional and range information to the rescue aircrew, locating downed pilots or other survivors. Compatibility with multiple platforms and aircraft, power and communications bus systems, in addition to the new functionality, is required.

Upgrade/Sustainment of the AN/ARS-6(V) PLS (as shown in Figure 1-1) was initiated by the program stakeholder, the US Army Communications Electronics Command (CECOM) - Logistics and Readiness Center - Fort Monmouth, New Jersey.

This unique sustainment project's goal is to upgrade the radio functionality, using Commercial off the Shelf (COTS) components and Open Architecture, while sustaining the service life of the AN/ARS-6(V) Receiver/Transmitter Unit, Control Display Unit, and Remote Display Unit. The three upgraded components of the AN/ARS-6A must be compatible with the current system's form, fit, and function in the rescue vehicle, typically the Blackhawk A and L model helicopters, or fixed wing aircraft.

In addition to functionality improvements, manufacturability is being improved by the application of DFM (Design for Manufacture) principles to the system. For ease of assembly and repair, and new smaller form factor applications (such as Blackhawk M and UAVs) the system will be streamlined and miniaturized. (See Figure 1-2)

Physically, the AN/ARS-6A will maintain the equivalent fit as the legacy version in existing applications through the use of a simple mounting bracket. These packaging improvements are based on use of COTS components and current packaging systems such as compact PCI bus architecture and industrial standard interconnect hardware. The smaller package and higher functionality pose a stringent thermal management challenge being met using SolidWorks and Algor thermal modelling at the EMPF. COTS components, designed for forced convection cooling, must be adapted for the conduction cooling needed in this application. The COTS commercial components must be mechanically protected from the higher shock and vibration of military environments.

One of the critical sustainment project milestones is passing the Airworthiness Requirements defined by the program stakeholder. Multiple tests must be passed to achieve this milestone, including environmental, Electromagnetic Interference (EMI), Electromagnetic Compatibility (EMC), and functional testing in aircraft.

To pass functional testing, compatibility with the GPS (Global Positioning System) and SARSAT (Civilian Satellite based search and rescue) waveforms, in addition to the Distance Measuring Equipment (DME) waveform used in the legacy system, is required. This requires that the COTS software defined radio (SDR) used must be able to be programmed with the legacy DME as well as the GPS and SARSAT waveforms. Compatibility with the new CSEL survival handheld radio will be attained using a Communications Interface Module (CIM) separately contracted with the CSEL vendor. Failure to pass these functional tests would indicate that the system is not acceptable for flight operations.

The environmental tests, defined in MIL-STD-810F, are intended to expose the hardware to the conditions it will experience during its service life. Conditions of shock, vibration, salt spray, among others, need to be tailored to fit the many potential service environments. A unique environmental requirement is that the display units in the AN/ARS-6A will have to be compatible with night vision goggles used by rescue aircrews. The LCD displays of the legacy radio have historically been a vulnerable point in the system, so the new systems will have both increased capability while also providing a more robust display solution.

EMI and EMC test procedures are provided in MIL-STD-461E; Department of Defense Interface Standard - Requirements for the Control of Electromagnetic Interference Characteristics of Subsystems and Equipment. This standard identifies the verification requirements for the control of electromagnetic compatibility (both EMI susceptibility and emissions) within RF (Radio Frequency) systems. This EMC requirement must be met for each of the different rescue vehicles in which the system might be deployed. Aircraft not having EMI shielded bus structures, usually the older types, present a greater EMC challenge than types having 1553, or Ethernet buses in which EMI shielding is present in the bus. Engineers at the EMPF recently addressed such EMI issues on the helicopter borne C6533/ARC intercom system in a similar re-design/sustainment effort. Through the use of selective filtering connectors and other mitigation techniques, it has been proven that good EMC performance can be attained.

The re-design/sustainment of the AN/ARS-6(V) PLS has presented design, packaging, and manufacturing issues. The new AN/ARS-6A re-designed system is currently a collaboration between the program stakeholder and ACI. The program stakeholder, CECOM, defined the system functional and sustainment issues. This strategy for developing and fielding the new, more functional, smaller and more manufacturable, AN/ARS-6A PLS to meet its mission, Airworthiness Certification, and program sustainment requirements is currently being implemented at the EMPF.