The lone test ranger
An exclusive interview with a test engineer
Martin Rowe -- Test & Measurement World, 2/1/2006
Bill Drago is a senior engineer at L-3 Communications Narda Microwave-East Division (Hauppauge, NY), which produces passive and active microwave components and subsystems. Products include amplifiers, filters, couplers, transceivers, multiplexers, isolators/circulators, up- and downconverters, channel amplifiers, power dividers, and combiners. Martin Rowe recently spoke with Drago about his work, which covers frequencies from DC to 30 GHz.
Q: What is your role in test?
A: I am the sole engineer at my division responsible for developing and maintaining automated test systems. I support design engineering and production. I define the test plans, configure test systems, write code, and train engineers and technicians on how to use the systems.
Q: What does a typical test system look like?
A: All of the systems I configure for engineering use benchtop equipment such as microwave sources, spectrum analyzers, vector network analyzers, power supplies, temperature sensors, and a digital I/O interface. Most equipment connects to a PC through an IEEE 488 port. The digital I/O module uses a USB port. We're always moving equipment around the lab, so engineering test systems must be flexible. In addition, I often build virtual control panels to control devices under test, which typically contain RS-232, RS-485, or I2C interfaces.
Q: What do your systems measure?
A: Typically, we measure gain, frequency response, return loss, and phase. In a recent test, I had to measure the response of an oscillator while we struck it with a hammer. It's a requirement for a military standard. I didn't automate the hammer movement, but I did automate the data processing that followed the impact. I spend my time automating data capture so the design engineers can analyze the results. I often need to quickly configure a data-acquisition system that will make measurements over a weekend and store the data.
Q: How do you support production?
A: Although I spend most of my time supporting engineering, production is my first priority. I supply and support production test systems. On a recent project, the unit under test was a portable spectrum analyzer for cell-phone towers. I designed the test system so that if a unit failed halfway through its 30 tests and the unit needed repair, the system knew which tests the unit had already passed. It didn't have to start from the beginning of the test sequence, but I gave the technician the option of rerunning a test.
Q: How do you get a product ready for production?
A: Once a product is ready for production, I take a subset of the engineering tools I developed and use them in an automated test system. To save time, we may use multiple signal sources so that we don't have to use microwave switches. Not all product test systems are built into racks. Some production systems sit on a bench for years. It depends on the budget.
Q: What are the most significant challenges you face?
A: Keeping up with demand is number one. Engineers come to me with test requirements and they need systems right away. Sometimes, they don't really know what they want, and I have to help them define their tests. I rarely have time to produce code with error checking because the engineers just need a system quickly. I've learned how to produce quality code. I know where not to go when writing code. Another challenge comes in trying to figure out how to program an instrument. Test equipment makers can help by improving their documentation.
