1 2 3 4 5 6 7 8 9 10-80

-60

-40

-20

0103.csv

DB

1.504 -3.8491

1 2 3 4 5 6 7 8 9 10-80

-60

-40

-20

0109.csv

DB

2.998 -9.748

1 2 3 4 5 6 7 8 9 10-80

-60

-40

-20

0111.csv

DB

3.808 -14.7667

FREQ

LOW COST RADAR; ERIC WALTON 2012 CERF PROJECTEric Walton, ElectroScience Laboratory, ECE Dept., The Ohio State University

Email: Walton.1@osu.edu;

Frequency Synthesizer• Windfreak SynthNV module • based on the Analog Devices ADF-4350• 400 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

SYN3 DB

SPLITTER

I/Q

MIXA/D

COMPUTER

USB

USB

I

Q

0.5-4.4 GHz

3.25 AND 5.88 INCH

DIAMETER SPHERES

1-12 GHz ridge-waveguide

UWB horns

1000 1500 2000 2500 3000 3500-70

-60

-50

-40

-30

-20

-10

0

10

20

FREQ

SIG

NA

L (D

B)

STABILITY TEST

EMPTYEMPTY2SUBTRACT

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.

0 20 40 60 80 100-100

-90

-80

-70

-60

-50

-40

-30

-20

TIME (ns)

SIG

NA

L (D

B)

EMPTYEMPTY2SUBTRACT

• 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.

1000 1500 2000 2500 3000 3500-4

-3

-2

-1

0

1

2

3

4sphere5p88.txt

FREQ (GHZ)

RA

W I/Q

da

ta

IN PHASEQUADRATURE

-4 -2 0 2 4-4

-2

0

2

4sphere5p88.txt

REAL)

IMA

GIN

AR

Y

EXAMPLE RAW DATA

EXAMPLE STABILITY TEST

1000 1500 2000 2500 3000 3500-40

-30

-20

-10

0

10

20divided/normalized sphere5p88.txt

sphere5p88.txtsphere5p88.txt normalizedempty

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

0 50 100 150 200-120

-100

-80

-60

-40

-20

sphere5p88.txt

sphere5p88.txtsphere5p88.txt normalizedemptysphere5p88.txt - backgroundsphere5p88.txt - BKG - NORMALIZED

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)

0 2 4 6 8 10 12 14 16 18-50

-45

-40

-35

-30

-25

-20

-15

sphere5p88.txt

sphere5p88.txtsphere5p88.txt normalizedemptysphere5p88.txt - backgroundsphere5p88.txt - BKG - NORMALIZED

0 2 4 6 8 10 12 14 16 18-70

-60

-50

-40

-30

-20

-10sphere3p25.txt

sphere3p25.txtsphere3p25.txt normalizedemptysphere3p25.txt - backgroundsphere3p25.txt - BKG - NORMALIZED

We can also do this

for the 3.25” diam sphere

BLOW UP

CONCLUSIONS;• WE HAVE BUILT A VERY USEFUL RADAR FOR LESS THAN $2,000.

• 400 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.

$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 bandwidth DC-275 MHz • 50 Ω• Input IP3 +30 dBm

Spectrumanalyzer

1.5 GHZ

3.0 GHZ

3.8 GHZ

FROM SPECTRUM ANALYZER TESTING; NOTE THE SIDELOBE STRUCTURE

I/Q PATTERN

10 HEARTBEATS

I

Q