Phasebridge Inc. of Pasadena, Calif., has received a $350,000 contract from the Defense Advanced Research Projects Agency to further develop an optical radio-frequency quadrature phase-shift-keyed technique (QPSK) and to analyze its applications in next-generation ultrawideband and frequency-agile military radio systems. The method will be used to imprint data during the frequency synthesis process in these "photonic radios." Under the contract, the company will enhance QPSK modulation as it pertains to ultrawideband photonic heterodyne frequency synthesis and photonic frequency conversion. The photonic radio architecture integrates the synthesis and conversion methods into a system that permits a baseband-frequency terminal to access a wide range of channel frequencies. The technology is expected to decrease significantly the size, weight and power consumption of military radio communications.