1. 34 rd Annual AMTA Symposium Bellevue, Washington USA October 21-26, 2012 A LOW COST RADAR SYSTEM FOR HEARTBEAT DETECTION Dr. Eric K. Walton The Ohio State University ElectroScience Laboratory 1330 Kinnear Road, Columbus, OH 43212 Mr. Benjamin K. Ozcomert Upper Arlington High School, Upper Arlington OH

2. 34 rd Annual AMTA Symposium Bellevue, Washington USA October 21-26, 2012 THIS PROJECT SPONSORED BY ESL - CERF 2 The Ohio State University ElectroScience Laboratory Consortium on Electromagnetics and Radio Frequencies (ESL-CERF)

3. 34 rd Annual AMTA Symposium Bellevue, Washington USA October 21-26, 2012 CERF; LOW COST RADAR Frequency Synthesizer Windfreak SynthNV module based on the Analog Devices wideband fractional-N synthesizer chip (with integrated VCO) Analog Devices ADF-4350 This mixed-signal chip can output signals in the 137-4,400 MHz range. This chip has enabled a number of very low cost modules to be developed. Our cost was $574. This module is very simple to set up and use. The USB port controls the device as well as providing power. signal output port RF reference signal input port available as option. power sense port The optional reference signal input port can be used for setting up several units coherently. The power sense port can be used to measure a received signal level, a nd thus this small unit can independently be used as a scalar network analyzer. The internal microprocessor can be programmed to operate independently by setting it to a particular frequency and power level. It can even be programmed to perform a step frequency scan automously. Photo of Windfreak SynthNV module 3

4. 34 rd Annual AMTA Symposium Bellevue, Washington USA October 21-26, 2012 BASED ON ANALOG DEVICES ADF 4350 Wideband synthesizer with integrated VCO 4

5. 34 rd Annual AMTA Symposium Bellevue, Washington USA October 21-26, 2012 Spectrum Analyzer Testing 5 1.5 GHZ 3.0 GHZ 3.8 GHZ FROM SPECTRUM ANALYZER TESTING; NOTE THE SIDELOBE STRUCTURE

6. 34 rd Annual AMTA Symposium Bellevue, Washington USA October 21-26, 2012 CERF; LOW COST RADAR I/Q Mixer (DEMODULATOR) There are a large number of UWB mixers available, Most require associated components (amps for LO and LP filters and amps for the IF output. We wanted to operated down to DC. We selected the Polyphase Microwave quadrature demodulator as a compromise between cost and performance. Bandwidth from 0.5 to 4.0 GHz with built in LO amplifier and I/Q low pass filters. Characteristics; LO/RF freq.500-4,000 MHz I/Q bandwidthDC-275 MHz (50Ω) Input IP3+30 dBm Input P1+12 dBm Amp. Imbal.+/- 0.05 dB Phase Error+/- 0.5 Deg. LO Power+0 dbm DC supply+/- 5 VDC This unit was purchased and tested using bench top laboratory equipment and was found to meet specifications. The unit was offered to The OSU ESL at an educational discount price of only $918.75. A photo of the unit is given in figure 7. I/Q Mixer (DEMODULATOR) There are a large number of UWB mixers available, Most require associated components (amps for LO and LP filters and amps for the IF output. We wanted to operated down to DC. We selected the Polyphase Microwave quadrature demodulator as a compromise between cost and performance. Bandwidth from 0.5 to 4.0 GHz with built in LO amplifier and I/Q low pass filters. Characteristics; LO/RF freq.500-4,000 MHz I/Q bandwidthDC-275 MHz (50Ω) Input IP3+30 dBm Input P1+12 dBm Amp. Imbal.+/- 0.05 dB Phase Error+/- 0.5 Deg. LO Power+0 dbm DC supply+/- 5 VDC This unit was purchased and tested using bench top laboratory equipment and was found to meet specifications. The unit was offered to The OSU ESL at an educational discount price of only $918.75. A photo of the unit is given in figure 7. Polyphase Microwave Inc.; 1111 W 17TH ST, STE 200 Bloomington, IN 47404 Polyphase Microwave Inc.; 1111 W 17TH ST, STE 200 Bloomington, IN 47404 $918.75. 6

7. 34 rd Annual AMTA Symposium Bellevue, Washington USA October 21-26, 2012 CERF; LOW COST RADAR 7

8. 34 rd Annual AMTA Symposium Bellevue, Washington USA October 21-26, 2012 CERF; LOW COST RADAR A/D CONVERTER 8 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

9. 34 rd Annual AMTA Symposium Bellevue, Washington USA October 21-26, 2012 CERF; LOW COST RADAR TESTING RESULTS SYNTH 3 DB SPLITTER I/Q MIXER A/D COMPUTER USB I Q 0.5-4.4 GHz 3.25 AND 5.88 INCH DIAMETER SPHERES 1-12 GHz ridge-waveguide UWB horns 9

10. 34 rd Annual AMTA Symposium Bellevue, Washington USA October 21-26, 2012 CERF; LOW COST RADAR IN PHASE AND QUADRATURE COMPONENTS VS. FREQUENCY EXAMPLE RESULTS FOR 5.88 IN. DIA. SPHERE 10

11. 34 rd Annual AMTA Symposium Bellevue, Washington USA October 21-26, 2012 CERF; LOW COST RADAR 11

12. 34 rd Annual AMTA Symposium Bellevue, Washington USA October 21-26, 2012 12 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. EXAMPLE STABILITY TEST

13. 34 rd Annual AMTA Symposium Bellevue, Washington USA October 21-26, 2012 13 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 below -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. STABILITY TEST; TIME DOMAIN

14. 34 rd Annual AMTA Symposium Bellevue, Washington USA October 21-26, 2012 CERF; LOW COST RADAR FREQUENCY (MHZ) Green = no-target data Blue = raw sphere data Red = sphere data divided by thru data DB 14

15. 34 rd Annual AMTA Symposium Bellevue, Washington USA October 21-26, 2012 CERF; LOW COST RADAR 15 TIME DOMAIN (ns) DB FULL TIME SCALE Coupling in pow. Divider (thus negative time)

16. 34 rd Annual AMTA Symposium Bellevue, Washington USA October 21-26, 2012 CERF; LOW COST RADAR 16 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})

17. 34 rd Annual AMTA Symposium Bellevue, Washington USA October 21-26, 2012 CERF; LOW COST RADAR 17 We can also do this for the 3.25 in diam sphere

18. 34 rd Annual AMTA Symposium Bellevue, Washington USA October 21-26, 2012 EXAMPLE FULL CALIBRATION TEST OF RADAR 18

19. 34 rd Annual AMTA Symposium Bellevue, Washington USA October 21-26, 2012 FULL CALIBRATION EXAMPLE LET US DO A FULL CALIBRATION TO REFERENCE SPHERES USING EXACT SPHERE RCS FOR REFERENCE. LET US DO A FULL CALIBRATION TO REFERENCE SPHERES USING EXACT SPHERE RCS FOR REFERENCE. H. L. Thal Jr., “Exact Circuit Analysis of Spherical Waves,” IEEE Transactions on Antennas and Propagation, vol. AP-26, No. 2, March 1978. RADAR APPROX 20 INCHES 1-12 GHZ RIDGED WAVEGUIDE HORNS STYROFOAM COLUMN SET OF TEST TARGETS AND REFERENCE SPHERES 19

20. 34 rd Annual AMTA Symposium Bellevue, Washington USA October 21-26, 2012 FULL CALIBRATION EXAMPLE 1.MEASURE TARGETS OF INTEREST (S21 VS. FREQ.) 2.SUBTRACT BACKGROUND (EMPTY TARGET SUPPORT) 3.TRANSFORM TO TIME DOMAIN 4.ZERO OUT ALL EXCEPT TARGET ZONE 5.TRANSFORM BACK TO FREQUENCY DOMAIN 6.NORMALIZE TO REFERENCE SPHERE 7.MULTIPLY BY EXACT RCS OF REFERENCE SPHERE 1.MEASURE TARGETS OF INTEREST (S21 VS. FREQ.) 2.SUBTRACT BACKGROUND (EMPTY TARGET SUPPORT) 3.TRANSFORM TO TIME DOMAIN 4.ZERO OUT ALL EXCEPT TARGET ZONE 5.TRANSFORM BACK TO FREQUENCY DOMAIN 6.NORMALIZE TO REFERENCE SPHERE 7.MULTIPLY BY EXACT RCS OF REFERENCE SPHERE 20 Note units of complex voltage and complex meters.

21. 34 rd Annual AMTA Symposium Bellevue, Washington USA October 21-26, 2012 FULL CALIBRATION EXAMPLE FOR THE FOLLOWING EXAMPLE, WE WILL USE A 3.5 INCH DIAM. SPHERE AS THE REFERENCE, AND A 2.5 INCH DIAM. SPHERE AS THE TARGET OF INTEREST. THAT WAY, WE CAN DOUBLE CHECK OUR ACCURACY BY COMPARING THE CALIBRATED 2.5 INCH MEASURED RCS VALUES WITH THE EXACT SOLUTION FOR THE 2.5 INCH SPHERE TARGET. FOR THE FOLLOWING EXAMPLE, WE WILL USE A 3.5 INCH DIAM. SPHERE AS THE REFERENCE, AND A 2.5 INCH DIAM. SPHERE AS THE TARGET OF INTEREST. THAT WAY, WE CAN DOUBLE CHECK OUR ACCURACY BY COMPARING THE CALIBRATED 2.5 INCH MEASURED RCS VALUES WITH THE EXACT SOLUTION FOR THE 2.5 INCH SPHERE TARGET. 21 The set of measurements on the different targets took place over a period of approximately 1 hour.

22. 34 rd Annual AMTA Symposium Bellevue, Washington USA October 21-26, 2012 FULL CALIBRATION EXAMPLE NOTE THE GAIN DROP-OFF OF THE RADAR NOTE THE I/Q BALANCE NOTE THE RESULT OF SUBTRACTING THE EMPTY SUPPORT DATA. 22

23. 34 rd Annual AMTA Symposium Bellevue, Washington USA October 21-26, 2012 FULL CALIBRATION EXAMPLE NOTE THE RESULT OF SUBTRACTING THE BACKGROUND AND THEN NORMALIZING TO (DIVIDING BY)THE REFERENCE SPHERE DATA. INCREASING NOISE 23

24. 34 rd Annual AMTA Symposium Bellevue, Washington USA October 21-26, 2012 FULL CALIBRATION EXAMPLE NEXT WE TRANSFORM THE SUBTRACTED & NORMALIZED DATA TO THE TIME DOMAIN. SET ALL OUTSIDE THIS TARGET ZONE TO ZERO ESPECIALLY REMOVE THE DIRECT HORN TO HORN COUPLING TERM 24

25. 34 rd Annual AMTA Symposium Bellevue, Washington USA October 21-26, 2012 FULL CALIBRATION EXAMPLE PLOT OF THE EXACT RCS (DBSM) OF THE 3.5 INCH SPHERE. 25

26. 34 rd Annual AMTA Symposium Bellevue, Washington USA October 21-26, 2012 FULL CALIBRATION EXAMPLE (FINAL CALIBRATION RESULT) NOTE THE AGREEMENT BETWEEN THE CALIBRATED TARGET AND THE EXACT CALCULATION. 26

27. 34 rd Annual AMTA Symposium Bellevue, Washington USA October 21-26, 2012 FULL CALIBRATION EXAMPLE WE CAN ALSO DO THIS FOR A 0.75 INCH DIAM SPHERE AS A TARGET. NOTE AGREEMENT 27

28. 34 rd Annual AMTA Symposium Bellevue, Washington USA October 21-26, 2012 FULL CALIBRATION EXAMPLE IN THIS CASE, THE TARGET OF INTEREST IS A 50 CALIBER BULLET (NOSE ON) WE INCLUDE THE EXACT RCS OF THE 0.75 INCH DIAM. SPHERE AS A REFERENCE. BULLET 0.75 “ D SPHERE EXACT 28

29. 34 rd Annual AMTA Symposium Bellevue, Washington USA October 21-26, 2012 FULL CALIBRATION EXAMPLE WE ALSO DID A MOM CALCULATION FOR THAT 50 CAL BULLET (Thanks; THE HONG LEE) 29

30. 34 rd Annual AMTA Symposium Bellevue, Washington USA October 21-26, 2012 FULL CALIBRATION EXAMPLE BULLET RADAR DATA FREQ NEAR NOSE ON BROADSIDE RCS (DBSM) NOT “TOO” BAD. 30 Overlay theoretical with experimental RCS (DBSM).

31. 34 rd Annual AMTA Symposium Bellevue, Washington USA October 21-26, 2012 FULL CALIBRATION EXAMPLE CONCLUSIONS; WE CAN BUILD A STEP FREQUENCY SYNTHESIZED RADAR USING MODERN MIXED SIGNAL MICROCHIPS FOR LESS THAN $2000. IT IS FULLY SOFTWARE CONTROLLED. USB INTERFACE TO LAPTOP FULLY PROGRAM CONTROLLED IN MATLAB (IN OUR CASE) WE CAN MEASURE RADAR TARGETS VERSUS FREQUENCY AND TRANSFORM THE RESULTS TO THE TIME DOMAIN. WE CAN PERFORM FULL CALIBRATIONS ON THE DATA TO YIELD RADAR SCATTERING IN DBSM. WITH GOOD DYNAMIC RANGE AND GOOD TIME STABILITY. WE CAN ALSO USE THIS RADAR IN THE SINGLE FREQUENCY MODE TO MEASURE DOPPLER. 31

32. 34 rd Annual AMTA Symposium Bellevue, Washington USA October 21-26, 2012 32 One of our goals is to extract I/Q Doppler waveform signatures from the human heartbeat. This is an I/Q Doppler measurement done with an ESL network analyzer on a volunteer. 1.5 GHZ I/Q PATTERN 10 HEARTBEATS I Q HUMAN HEARTBEAT MEASURED USING NETWORK ANALYZER IN CW VS. TIME MODE. 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.

33. 34 rd Annual AMTA Symposium Bellevue, Washington USA October 21-26, 2012 33 1.5 GHz Trajectory (EKW volunteer) 2.0 GHz Trajectory (EKW volunteer) HUMAN HEARTBEAT [HOW CAN WE ASCRIBE MEANING TO THESE TRAJECTORIES?] HUMAN HEARTBEAT [HOW CAN WE ASCRIBE MEANING TO THESE TRAJECTORIES?] MEDICAL INTERPRETATIONS?

34. 34 rd Annual AMTA Symposium Bellevue, Washington USA October 21-26, 2012 FULL CALIBRATION EXAMPLE QUESTIONS? DR. ERIC K. WALTON THE OHIO STATE UNIVERSITY ELECTROSCIENCE LABORATORY 1330 KINNEAR ROAD COLUMBUS, OHIO 43212 Walton.1@osu.edu Office 614/292-5051; cell 614/537-5609 34 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.

35. 34 rd Annual AMTA Symposium Bellevue, Washington USA October 21-26, 2012 35 spare