Hybrid addresses RF test

Dr. Francesco Lupinetti CTO Aeroflex Test Solutions Courtesy of Aeroflex.

Q: What challenges were you trying to solve with SMART^E?

A: The idea for SMART^E came from our desire to take technology from our radar group and apply it to test. We had fast, general-purpose tunable upconverters and downconverters and signal processors in VXI that we wanted to use to increase test throughput as compared to rack-and-stack systems. We originally developed a system based on a custom chassis with the upconverters, downconverters, local oscillator, and such, but we wanted to move that design into a hybrid architecture that could include a commercial-off-the-shelf (COTS) component. We initially developed the system for use in testing advanced reconfigurable ground combat systems (ARGCS), and then we expanded to include satellite payload testing, RF/microwave test, and radar transmit/receive module testing.

Q: What motivated the incorporation of both PXI and LXI in your design?

A: We were seeing creeping obsolescence in VXI elements in the system that we needed to upgrade, such as the arbitrary waveform generator and the digitizers. We found we could transfer those design elements to PXI and achieve price and performance improvements. Also, the move to PXI gave us access to additional technologies and a range of selections we really liked for other system elements. In addition, PXI offered us very nice functionality and an increase in interface speed compared to VXI.

The local oscillator and RF and IF upconverters and downconverters are in LXI because they need lots of onboard computing power. In addition, we use LXI because both control and data interfaces can use high-speed Ethernet, like the rest of the system elements in SMART^E.

Q: What challenges did you face in creating this hybrid system?

A: The architecture was already proven in an earlier version, but as you make changes to the configuration, there are always issues. In RF/microwave instruments, you are fighting different noise sources in every configuration due to fans, layout issues, cross-coupling, and the like. Also, you need the ability to tune the system for test-speed performance because it is mostly used in high-volume test. Adaptive radar systems, for instance, use hundreds to thousands of transmit/receive modules to control the direction of the beam, and fast testing of each of these elements and subassemblies reduces production costs. Performance is also important in satellite payload testing where millions of measurements may be needed.

Q: What advantages did the hybrid approach provide?

A: Hybrid modularity gives an ability to select system components and adapt the test instrument to the needs of an application. It also addresses the problem of obsolescence. For example, if you need to increase the frequency range, you can design and replace modules rather than developing a whole new instrument. The whole approach of the synthetic hybrid test environment is the way things will have to go in the future.