Test Connections - May 2011

Satellite Manufacturer Uses PXI-Based Interface Simulators for Design Verification

Surrey Satellite Technology Ltd (SSTL), based in the U.K., designs, manufactures and operates high-performance satellites and ground systems. Traditionally, satellite development has been a linear process, specifying everything up front, then designing, testing, assembling and verifying the flight unit. This approach requires not only a great deal of preliminary design work, but also a lot of design rework during sub-system integration.  
GX7300 GX7300 3U PXI Chassis with Smart Features
To reduce the amount of rework, SSTL uses simulators during the development process. Developers can use simulators to discover and resolve design issues early in the process, and they can use interface simulators to identify and resolve sub-system integration problems. Problem/challenge SSTL is currently involved in developing a simulator framework product that will allow the company to redeploy a common single platform for a variety of applications. The company had two primary concerns:

  • The potential for UUT damage. A single-point failure of the simulation product can destroy millions of dollars of flight equipment and cause extensive development delays.

  • Flexibility. SSTL needed a solution that was reconfigurable to its specific needs.
Solution SSTL needed to find a reliable simulation solution that fit within its budgetary restrictions. After researching available solutions, SSTL decided to base the hardware interfaces primarily on the PXI Standard, with Geotest-Marvin Test Systems and Pickering Interfaces as the main suppliers. "The biggest draw to the Geotest PXI chassis products is the safety monitoring features," said Mathew Maher, simulation team leader at SSTL. "This provides our second line of defense for the test equipment." The monitoring allows the company to take remedial action before a potential failure becomes critical. The equipment's first line of defense varies depending on the interface. Isolated interfaces are best. For more complex interfaces, SSTL uses Geotest’s GX3500 FPGA architecture with its daughter board interfaces as a development platform. The GX3500 FPGA board also addresses the flexibility problem. Because the space industry doesn't usually follow formal standards, the company needed a solution that it could configure to meet its needs. The GX3500 FPGA board provides the perfect platform for this customization. It comes with a wide range of drivers and is not locked into a single vendor solution. Ultimately, the decision to go with Geotest rested on the fact that its solutions fit SSTL's requirements rather than forcing SSTL's requirements to fit the solution. If Geotest didn't offer the right product, it agreed to develop the product that SSTL needed. "We design our products and Geotest designs the test components," said Maher. "This is in comparison to having a supplier telling us how to design our products to fit into their offerings." A win-win relationship SSTL's relationship with Geotest, though still in its infancy, has been successful and rewarding. According to Maher, the custom developments that Geotest is undertaking for SSTL are the result of long conversations and good cooperation. He added that Geotest is developing products SSTL needs, but the products are general enough to be worthy sales products in their own right. It's a win-win situation.
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