The Direct Digital Phase Noise Measurement Phase 1 SBIR demonstrated the feasibility of the technology to make the measurements required by the commercial marketplace. This new approach to phase noise measurements uses fast digital-to-analog converters to digitize the input RF signal and performs all down-conversion and phase detection functions by digital signal processing. It has several significant advantages over analog phase noise measurements techniques: there is no external phase-lock loop, oscillators can be compared at different frequencies, amplititude and phase noise spectra and Allan variance may be measured simultaneously, and complex calibration techniques are eliminated. COMMERCIAL APPLICATIONS: Direct digital phase noise measurement instruments will replace analog measurement instruments wherever they are competitive in performance for two reasons. They will have lower acquisition cost resulting from the elimination of expensive low noise analog electronics. They will also have lower operating cost since they will not require skilled personnel to make good measurements. Phase noise measurements are routinely made for oscillators used in communications, radar, signal intelligence, and navigation. This research could lead to a commercial phase and amplitude noise measurement instrument that 1. Requires much less expertise to use than the presently available equipment. 2. Produces more accurate results. 3. Can be operated in situ because it does not require phase-lock loops to maintain quadrature between the sources
