LOW COST RADAR; ERIC WALTON 2012 CERF PROJECT Eric Walton, ElectroScience Laboratory, ECE Dept., The Ohio State University Frequency Synthesizer Windfreak SynthNV module based on the Analog Devices ADF TO 4,400 MHz USB controlled and powered $574 MEASUREMENT COMPUTING USB-7202 ONE A/D PER CHANNEL UP TO 8 SIMULTANEOUS INDEPENDENT RANGE SETTINGS 16-BITS USB POWERED 100 KS/S CUMULATIVE RATE (IE; 50 KS/S EACH CHAN. FOR TWO ETC.) SIMULTANEOUS SAMPLING DOUBLE SPEED IN BURST MODE (32 K INTERNAL FIFO) $399 PRELIMINARY TESTING SYN 3 DB SPLITTER I/Q MIX A/D COMPUTER USB I Q GHz 3.25 AND 5.88 INCH DIAMETER SPHERES 1-12 GHz ridge-waveguide UWB horns IT IS CRITICAL THAT THE RADAR SYSTEM BE STABILE AND REPEATABLE FROM SCAN TO SCAN SO THAT SCANS CAN BE DIRECTLY COMPARED AND SO THAT THE BACKGROUND CAN BE SUBTRACTED FROM THE DATA OF INTEREST AS WELL AS SO THAT THE “THRU” DATA CAN BE USED FOR NORMALIZATION. As a stability test, the empty target support at the beginning of the series can be compared to the one at the end; (time elapsed = 20 minutes) Note the difference is less than -25 dB. IF WE LOOK AT THE EMPTY VS. EMPTY DATA IN THE TIME DOMAIN, WE NOTE THAT THE MOST STABILE REGION IS NEAR THE ANTENNA COUPLING REGION. (difference less than -35 dB) IT IS LESS STABILE AT TIMES GREATER THAN 20 ns. This may be simply due to people moving around near the measurement system. EXAMPLE RAW DATA EXAMPLE STABILITY TEST FREQUENCY (MHZ) Green = no-target data Blue = raw sphere data Red = sphere data divided by thru data DB EXAMPLE RESULTS FOR 5.88” DIA. SPHERE TIME DOMAIN (ns) DB FULL TIME SCALE Coupling in pow. Divider (thus negative time) TIME (ns) DB NOTE; 1.background subtraction suppresses the room clutter (background) by more than 30 dB. 2.Normalization to the “thru” connection removes the effects of system and cables. (IE: moves the response from 11.2 ns to 4.2 ns. {antennas and propagation distance remain}) We can also do this for the 3.25” diam sphere BLOW UP CONCLUSIONS; WE HAVE BUILT A VERY USEFUL RADAR FOR LESS THAN $2, TO 4,400 MHz; SYNTHESIZED OUTPUT POWER (-30 TO 0 DBm) (COMPUTER CONTROLLED) EXCELLENT SENSITIVITY AND REPEATABILITY PORTABLE (LAPTOP CONTROLLED) RUNNING TOTALLY IN MATLAB CAN OPERATE IN STEP FREQUENCY MODE CAN OPERATE IN SINGLE FREQUENCY(WITH DOPPLER) MODE. CONCLUSIONS; WE HAVE BUILT A VERY USEFUL RADAR FOR LESS THAN $2, TO 4,400 MHz; SYNTHESIZED OUTPUT POWER (-30 TO 0 DBm) (COMPUTER CONTROLLED) EXCELLENT SENSITIVITY AND REPEATABILITY PORTABLE (LAPTOP CONTROLLED) RUNNING TOTALLY IN MATLAB CAN OPERATE IN STEP FREQUENCY MODE CAN OPERATE IN SINGLE FREQUENCY(WITH DOPPLER) MODE. 6. Acknowledgements The authors wish to thank The Ohio State University ElectroScience Laboratory Consortium on Electromagnetics and Radio Frequencies (ESL-CERF) (sponsors of this project) as well as Polyphase Corporation for their assistance. 6. Acknowledgements The authors wish to thank The Ohio State University ElectroScience Laboratory Consortium on Electromagnetics and Radio Frequencies (ESL-CERF) (sponsors of this project) as well as Polyphase Corporation for their assistance. $918 (Univ. Disc.) 1.5 GHZ In the future; One of our goals is to extract I/Q Doppler waveform signatures from the human heartbeat. On the left is an I/Q Doppler measurement done with an ESL network analyzer on a volunteer. Note the repeating I/Q pattern synchronized with the heartbeat. We hope to collect more of this type of data using our new portable radar and to compare the I/Q signature with MRI or EKG data. Polyphase Microwave I/Q demodulator 0.5 to 4.0 GHz built in LO amplifier Built in I/Q low pass filters. Characteristics; LO/RF freq.500-4,000 MHz I/Q bandwidthDC-275 MHz 50 Ω Input IP3+30 dBm Spectrum analyzer 1.5 GHZ 3.0 GHZ 3.8 GHZ FROM SPECTRUM ANALYZER TESTING; NOTE THE SIDELOBE STRUCTURE I/Q PATTERN 10 HEARTBEATS I Q