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Abstract

A direct digital sampling and synthesis general purpose radio system is disclosed which employs single or multiple receiver and/or transmitter sub-systems that require no analog frequency conversion or translation circuitry. Receiver signal processing is disclosed that describes methods of conditioning and digitizing an entire received RF signal band in which the down conversion, channelization and demodulation are performed digitally. In addition, a method for direct synthesis of transmitter signals is also disclosed where up conversion and carrier modulation is performed digitally. Several mitigation techniques are described which aid in overcoming device limitations as well as overcoming problems created by combining multiple digital transmitters and receivers into a single integrated system. One embodiment of the invention describes an integrated VHF/UHF aircraft NAV/COMM radio system which combines a VHF transmitter with four VHF/UHF receivers all of which require no IF circuitry. This embodiment allows for multiple simultaneous airborne radio services on a single platform such as voice and data communication modes (AM, ACARS, VDLM2, LAAS, etc.) as well as navigational modes such as VOR, ILS, and Marker Beacon. By utilizing direct digital methods, the signal processing burden is moved almost entirely to the digital domain where the processing can be optimized for each signal type and where linearity is guaranteed. Fewer RF components are required which result in less unit to unit variability, lower production costs, and improved reliability.

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First Claim