Application or Digital Technology to OMEGA Simulation and Monitoring

Benjamin Peterson, John Boynewlcz, Thomas Routhier, Terry Toy

Abstract:	A summary of three OMEGA related projects completed within the past year is presented. First the design of an optimum, all digital OMEGA receiver intended mainly for research/monitoring purposes is described. After sampling the antenna signal at 200 kHz and 13 bits, the signal is digitally mixed with the sine and cosine of the OMEGA carrier frequency. The mixer outputs arc lowpass filtered and averaged and the phase and signal strength arc calculated from these averages. The main features of this receiver are: (1) For Gaussian distributed noise, the phase estimates for each station are optimum in a maximum likelihood sense; (2) Each station's signal strength and the total noise power are directly measured; (3) Monitoring of all OMEGA frequencies including the unique frequencies is possible. Also described is an automated monitoring and data processing system for the existing Magnavox MXl l 04 receiver. The data is stored on floppy disks in a linked list of records. This system is intended to streamline the processing of OMEGA data. A third project presented is an OMEGA simulator. based on digital synthesis via second order homogeneous difference equations. The simulator is implemented on a Texas Instruments TMS32020 microprocessor based Ariel DSP-16 plug-in board installed in a NEC APC-IV (PC-compatible) portable computer. Based on user inputs of phase and magnitude of all eight OMEGA stations at three of the navigational frequencies. initial conditions for the oscillators and gains are calculated by the computer and downloaded to the TMS32020. By making all delay loops, difference equation coefficients, and initial conditions explicit functions of the quartz oscillator frequency all synthesized frequencies and the overall timing is controlled to within 5 parts in 107. This capability also permits easy transport to systems with different clock frequencies. This ·simulator together with a similar LORAN simulator will be used by the Coast Guard COMDAC Support Facility to test OMEGA and LORAN receivers on Famous Class cutters.
Published in:	Proceedings of the 45th Annual Meeting of The Institute of Navigation (1989) June 27 - 29, 1989 Alexandria, VA
Pages:	119 - 123
Cite this article:	Peterson, Benjamin, Boynewlcz, John, Routhier, Thomas, Toy, Terry, "Application or Digital Technology to OMEGA Simulation and Monitoring," Proceedings of the 45th Annual Meeting of The Institute of Navigation (1989), Alexandria, VA, June 1989, pp. 119-123.
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