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Ultra-Broadband, High Dynamic Range Receiver System


OBJECTIVE: Design and develop an ultra-broadband, high dynamic range receiver system for signal capture, storage, and analysis. DESCRIPTION: Recent technological advances have enabled downconversion and sampling of radio-frequency (RF) signals with high instantaneous bandwidth and fidelity. Applications include recordings of threat signals, jamming waveforms, civilian systems, and other signals of interest for detailed analysis and potential upconversion and playback at RF for replication of these in-the-field collected signals in a laboratory environment. As bandwidth and fidelity of these recordings increase, the subsequent improvement in quality of the recordings has resulted in an increased relevance and potential applications in the test and evaluation arena. Especially of interest is the cost savings that stimulation of military receiver systems via playback of these high-fidelity recordings at RF can provide via optimization and testing in a laboratory environment vice far more costly open-air (flight) testing. A system capable of providing up to 6 GHz of instantaneous bandwidth and at least 12 bit signal fidelity, thereby providing over 70 dB of spur-free dynamic range (SFDR), is desired. The bandwidth must be instantaneous, not a scan and tune architecture, in order to capture 100 percent of low-duty cycle signals. The resulting system should allow for the 6 GHz of instantaneous bandwidth to be centered, or tuned anywhere between 3 GHz center frequency (providing DC-6 GHz coverage) or 23 GHz center frequency (providing coverage from 20-26 GHz). The system should provide real-time recording capability of these signal bandwidths for durations of up to 15 minutes in open file format allowing the files to be ported to a workstation for analysis and manipulation. The current state of the art is a DC-6 GHz bandwidth, 8-bit recording and playback system. Additionally there is a 12-bit system which has 1 GHz of instantaneous bandwidth, with the 1 GHz of bandwidth centered at a frequency tunable from 2 GHz to 26 GHz. That system can be equipped to record signals for over 1 hour but requires substantial hard drive storage. Novel receiver architectures will be required in order to overcome the challenges in exceeding the currently state of the art with respect to the bandwidth-bits product figure of merit. Novel system designs are sought capable of tuning such a large bandwidth over such a large frequency range. Identify and explore novel system and receiver hardware architectures capable of furthering the state-of-the-art, and what the potential state-of-the-possible is for each of the proposed approaches. PHASE I: Identify and develop an approach, and determine technical feasibility through modeling and simulation or other means. PHASE II: Develop and demonstrate a prototype system for capture and storage of an input RF environment. Demonstrate signals sufficiently diverse in signal strength and frequency simultaneously input to the prototype in order to exercise the limits stated in the description. PHASE III: Acceptance testing of the developed system should be completed and the resulting technology transitioned to appropriate platforms and customers. PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: This improvement in state-of-the-art for receiver bandwidth-fidelity product would radically increase capabilities in electronic surveillance for e.g. law enforcement applications. Communication links requiring high bandwidth and fidelity will benefit: applications include microwave links found in cellular backhaul links and cognitive radio applications which would benefit from the improved spectrum-sensing capabilities of the proposed receivers. REFERENCES: 1. Tsui, J. (2004). Digital Techniques for Wideband Receivers (2nd Ed). Norwood, MA: Artech House, Inc. 2. Edde, B. (1992). RADAR: Principles, Technology, Applications. Upper Saddle River, NJ: Prentice Hall.
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