Low Cost 40Mhz RF Power MeterGroup: DEC13-04

DEC13 -04

Team DEC13-04 Composition

• Students: Jason Danielson Jiwei Xia Tyler Christesen Yilun Ji

• Client : Dan Stieler PowerFilm, Inc

• Advisor: Dr. Ayman Fayed

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PowerFilm Solar• Uses RF Power generators to determine the amount of material that is applied to thin-film solar cells

• Too much or too little power results in efficiency and quality issues

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Client Requirements• A through-line RF power meter able to accurately detect a 40MHz pulsed signal

•Digital output and display

• Logging software for up to 20 devices

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Commercial Product Drawbacks• Mechanical display only available on the meter itself

• No way to monitor or troubleshoot problems

• ExpensiveBird 43 Watt Meter

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The Plan• Use existing technology and improve on it with value added features

• Analog signal Digital signal

• Attach an LCD to the meter

• Send data to logging software

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The StructureRF Generator

MicrocontrollerBird 43 Watt Meter

Wireless LAN Transmission

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Bird Meter (Bird Model 43)•Company Bird Model 43 bird Technology Company•Price 200 dollars each

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How it connects to generator and output device•Example•Plug in element (Slug)

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Direction of the arrow shows we are measuring forward power

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Circuit Structure

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MSP430 Launchpad

Microcontroller uses

• Driving LCD

• ADC (Analog to Digital conversion

• Sending Data to Computer

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Driving LCD From MSP430 Launchpad

5V 16x2 character LCD

Set up in 4 bit mode, send 4 upper bits of byte then the 4 lower bits.

Used to display the digital readingof the ADC

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ADC

10 bits of resolution (2^10=1024 steps)

0-3.6V sensitive

Results in 3mv each step

ADC Step

ADC Step Vs. Input Voltage

Input Voltage

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Inner structureStep 1 step 2 step 3

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Collected Data: Power VS current

50% Duty Cycle (uA)75% Duty Cycle (uA)

100% Duty Cycle (uA)

Power Supplied by RF Generator (W)

With 1.4k resistor, no needle 100% Duty Cycle (uA)

no needle, no resistor, 100% (uA)

0.30 0.40 0.76 10 0.76 0.780.55 0.78 1.34 20 1.34 1.390.79 1.15 1.84 30 1.86 1.931.03 1.51 2.34 40 2.33 2.421.25 1.85 2.77 50 2.76 2.871.47 2.17 3.17 60 3.16 3.291.68 2.48 3.56 70 3.55 3.71.89 2.77 3.93 80 3.92 4.082.08 3.06 4.27 90 4.25 4.442.27 3.33 4.61 100 4.60 4.793.15 4.56 6.11 150 6.09 6.363.94 5.63 7.35 200 7.40 7.714.65 6.56 8.47 250 8.56 8.926.50 9.00 11.20 400 11.63 12.067.58 10.41 12.72 500 13.34 13.77

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Data Plots: Power VS current

0 2 4 6 8 10 12 140

100

200

300

400

500

600

f(x) = 4.13451906737163 x² + 34.6392181143127 x − 0.126073423739026R² = 0.999995484672931f(x) = 2.61995077486335 x² + 20.5139302422697 x + 2.615634749069R² = 0.999983645933284

f(x) = 2.22557451237847 x² + 10.6328713112411 x + 2.75577349655365R² = 0.999913978200174

Power VS Current

100% Duty Cycle (uA)Polynomial (100% Duty Cycle (uA))75% Duty Cycle (uA)Polynomial (75% Duty Cycle (uA))50% Duty Cycle (uA)Polynomial (50% Duty Cycle (uA))

Current(uA)

Power (W)

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Voltage for Unit 1 (mV) Voltage for Unit 2

(mV) Power

(W) Difference Difference%1.2 1.2 10 0 0%2.3 2.2 20 0.1 4%3.3 3.2 30 0.1 3%4.2 4.1 40 0.1 2%

5 4.9 50 0.1 2%5.9 5.7 60 0.2 3%6.7 6.5 70 0.2 3%7.4 7.2 80 0.2 3%8.1 7.9 90 0.2 2%8.6 8.5 100 0.1 1%

10.4 10.1 125 0.3 3%11.7 11.5 150 0.2 2%13.3 12.9 175 0.4 3%14.3 14.1 200 0.2 1%15.8 15.3 225 0.5 3%16.7 16.4 250 0.3 2%18.1 17.6 275 0.5 3%18.9 18.6 300 0.3 2%20.3 19.6 325 0.7 3%

21 20.7 350 0.3 1%22.3 21.7 375 0.6 3%22.9 22.7 400 0.2 1%24.2 23.5 425 0.7 3%

26 25.1 475 0.9 3%26.5 25.9 500 0.6 2%

Collected Data: Power VS Voltage

0 5 10 15 20 25 300

100200300400500600

f(x) = 0.000781285 x³ + 0.39641333 x² + 8.46666936 x − 1.17936033R² = 0.999906286554759

Power Vs Voltage for Meter 1

Power (W)Polynomial (Power (W))

0 5 10 15 20 25 300

100200300400500600

f(x) = 0.000781285 x³ + 0.3964133 x² + 8.4666694 x − 1.1793603R² = 0.999906286554759

Power Vs Voltage for Meter 2

Power (W)Polynomial (Power (W))

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Collected Data: Difference in the two meters

0 100 200 300 400 500 6000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Difference Beween Two Meters

DifferenceLinear (Difference)

0 100 200 300 400 500 6000%

1%

2%

3%

4%

5%

Difference%

Difference%Linear (Difference%)

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Software

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Questions?