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LOW COST RADAR2012 CERF PROJECT

ERIC WALTONOSU/ESL

JULY 2012

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CERF; LOW COST RADARA/D CONVERTER

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

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CERF; LOW COST RADARFrequency 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

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BASED ON ANALOG DEVICES ADF 4350

Wideband synthesizer with integrated VCO

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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 bandwidth DC-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 200Bloomington, IN 47404

$918.75.

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CERF; LOW COST RADAR

7

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CERF; LOW COST RADAR

TESTING RESULTS

SYNTH 3 DB SPLITTER

I/Q MIXERA/D

COMPUTER

USB

USB

I

Q

0.5-4.4 GHz

3.25 AND 5.88 INCH DIAMETER SPHERES

1-12 GHz ridge-waveguideUWB horns

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CERF; LOW COST RADAR

1000 1500 2000 2500 3000 3500-4

-3

-2

-1

0

1

2

3

4sphere5p88.txt

FREQ (GHZ)

RA

W I/

Q d

ata

IN PHASEQUADRATURE

IN PHASE AND QUADRATURE COMPONENTS VS. FREQUENCY

EXAMPLE RESULTS FOR 5.88 IN. DIA. SPHERE

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CERF; LOW COST RADAR

-4 -2 0 2 4-4

-2

0

2

4sphere5p88.txt

REAL)

IMA

GIN

AR

Y

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CERF; LOW COST RADAR

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 dataBlue = raw sphere dataRed = sphere data divided by thru data

DB

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CERF; LOW COST RADAR

0 50 100 150 200-120

-100

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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)

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CERF; LOW COST RADAR

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

-45

-40

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-25

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sphere5p88.txt

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

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)

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CERF; LOW COST RADAR

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

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-10sphere3p25.txt

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

We can also do this for the 3.25 in diam sphere

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CERF; LOW COST RADAR

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.

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BACK-UP

• BACK UP SLIDES;

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CERF; LOW COST RADAR

2 4 6 8 10 12 14 16 18-70

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-10spherenoh5p88.txt

spherenoh5p88.txtspherenoh5p88.txt normalizedemptyspherenoh5p88.txt - backgroundspherenoh5p88.txt - BKG - NORMALIZED