Tuning in the time domain
"I had come across a really interesting technical phenomenon," he
said. "Tuning filters for base stations and wireless was a big
thing for test equipment. There would be hundreds of network
analyzers with rows of people tuning filters. We were developing a
new high-speed processor to make them faster. I had one channel
that was doing high-speed filter tuning and the other for Fourier
transforms. When I tuned the filter in the frequency domain,
something weird was happening in the timing domain. I'd never
noticed that before."
"I discovered you could tune filters in the time domain and faster
than in the frequency domain," Dunsmore said. An Agilent
consultant at the time turned out to be the dean of engineering at
the University of Leeds, which is where Dunsmore ended up doing
his Ph.D work.
"I said to him do you think that would be a good thesis topic? He
said yes," Dunsmore recalled.
A few years later, Agilent elevated him to Fellow, where he
continues wrestling to the ground the measurement problems of
Last foot challenge
"Clearly the biggest (test challenge) is the last foot from the
test equipment to the device the customer is measuring," Dunsmore
said. "It's that interface that causes worlds of difficulty. The
last patent I applied for focused on that interface. You could
measure a cell phone and there's no connector on cell phone, so
you have to deal with a radiator into the phone. What about a
wireless chip with optical link on one end and wireless link on
the other and no place to connect?"
Separately, what about "a tiny little chip with bunch of
connectors? Our customers want to test their chip as though
nothing else was connected to it. That's the 'fixturing' problem,"
And, like a relentless drumbeat, there's optimization and
integration of each new generation of T&M equipment.
"Intelligent optimization is a really interesting area," Dunsmore
said. "We'll need to control a lot more things and not test just
one thing at a time."
The son of parents whose career was made with their hands has made
his with his head, and, along the way, imparted some of that
wisdom to college students, with teaching stints at U.C. Berkeley.
And, in an age of constant relocation, Dunsmore has stayed at the
same company since his internship.
While HP was a big company, Agilent is a big company as well that
affords him opportunities.
"When you move from job to job, it's like moving from
company to company," Dunsmore said. "I never felt like I was
getting stuck in a spot where I was button-holed. I've done
optical work, moved into microwave and then into wireless
Cell-aware automatic test methods improve test quality
Basics of testing op amps, Part 4: Testing op amps requires stable test loops
Signal Chain Basics #73: Audio metering, enjoying the VU
ADC Basics (Part 5): Key ADC specifications for system analysis