Military aircraft depend
on analog technology
to detect enemy
ground radar. Analog
circuits can hold a multitude of continuous
values across any given range. But this
continuous-scale analog implementation
can be difficult to calibrate and maintain
in radar warning receivers. So,
scientists at the Georgia Tech
Research Institute have turned to the digital domain, which doesn't need calibration and is more robust.
Their digital crystal video
receiver (DCVR) is part of the
radar warning receiver (RWR)
system, which detects ground-radar activity ().
Comprising an analog-to-digital converter (ADC) and a programmable logic component,
it takes charge of the logarithmic transfer function that
coordinates the input and output of the RWR's signal processing system.
"Electronic analog technologies have
a number of error sources and limitations when subjected to the extended
temperature range that our military
requires," says GTRI researcher Michael
Willis. "By moving the logarithmic transfer function into the digital signal-processing domain, we've improved the stability of the circuit."
The digital version of the technology
also is much less expensive to manufacture. Willis expects the shift from analog
to digital to reduce RWR production
costs by a factor of five to 10, making its
costs nearly insignificant compared to
the rest of the system.
Furthermore, previous crystal video
receiver architectures detected RF signals
immediately without intermediate processing, but they needed multiple receivers to detect
radar signals over a range of
frequencies. Instead, the DCVR
can detect RF signals through a
range of frequencies using up-to-date broadband receiver
techniques.
GTRI and the U.S. government have patented the technology. Willis expects the
design process and transition
from implementation to production to take two years.
Georgia Tech
www.gtri.gatech.edu
