Portland, Ore. -- A new breed of ultrawideband radio that uses a mixer instead of a delay line could solve longstanding deployment problems, its developers say. The technique, invented by engineers at the University of Massachusetts (Amherst), was unveiled last week at the International Conference on Ultra-Wideband in Waltham, Mass.
"For many ultrawideband applications, such as monitoring patients in a hospital, you only need low data rates for telemetry like heart rates and respiration, but you need to know exactly where the patient is located," said Dennis Goeckel, electrical and computer engineering professor at UMass.
One of the most promising approaches to UWB was to send a nanosecond reference pulse before each data pulse, giving the radio a time frame in which to search its spectrum for data bits. However, after nearly a decade of attempting to use delay lines to synchronize data collection, most research into that approach has come to a halt, Goeckel said.
"You wouldn't have thought a 20-ns delay line was so difficult to build, but everybody has pretty much given up," he said. So Goeckel and doctoral student Qu Zhang "came up with a fresh approach that works." A team of faculty and students developed a prototype in nine months, Goeckel added.
The new approach scraps the delay line idea for a mixer, which is easy to build even for ultrashort pulses. A reference pulse is still sent, but is mixed together with the data bit and multiplied by a cosine. On the receiving end is another mixer, with one input coming from the antenna and one from a sine wave generator. "All the receiver has to do is integrate the mixers' output to determine whether the transmitted bit was a one or a zero," said Goeckel. "We hope it will be adopted by the standards committee."