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Published byGiles Wilcox Modified over 9 years ago
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Pseudo-Random Noise Radar n Prototype Design –Small inexpensive “correlation-type” receiver –Digitally produced Pseudo-Random Noise (PRN) for transmitter –Upconversion Board –Low-Profile Ultra Wide-band Synthetic Aperture Antenna Array
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PRN Generator n The heart of the system
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PRN Generator (cont’d) n PC Controlled n Produces two identical pseudo-random waveforms with a user-defined delay between. n Through software, delays can be manipulated to scan entire delay span, partial delay span, or any points therein. n Bandwidth of output noise dependant only on clock-speed of PRN circuit
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Upconverter n Basic circuit to convert base-band noise to transmission spectrum of 3 - 3.8GHz.
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Optional BPF Filter Board n Can be used to replace Upconverter if large amplification of PRN harmonics is used. n Currently Not used in system
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Receiver / Antenna Array
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Antenna Array n Gain of 8+ dBi n Side-by-side elements can be used for isolated measurements (SAR) due to high isolation. (20dB 1st Adjacent - 30dB 2nd Adjacent) n Usable Bandwidth on order of GHz
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Antennas (cont’d)
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Receiver n Small - inexpensive –Each channel only requires mixer chip, op- amp chip, RF amplifier chips and discrete components (resistors etc) n Analog integration allows data collection on the order of milliseconds, and reduced noise through averaging. n Preliminary tests show minimum detectable signal at -80dBm.
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Prelim RX Testing Experiment
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System Integration
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First System Test
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First System Test (cont’d) n SNR non-optimal due to drastic op-amp output drift with temperature n Problem remedied with low-drift op-amp n No range data taken yet after improvement, but 45dB reduction in noise floor recorded
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From here... n Fabrication of improved PRN Generator will provide 7 inch downrange steps to a maximum of 280 feet. n 4 Antennas and Receivers increased to 40 for Synthetic Aperture Imaging n Other possible applications for PRN radar
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