Lab Group L2BxEECE 380 – Electrical Engineering Design Studio (Spring 2014)

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Spectrum Analyzer

Michael Halpenny-Mason, Presenter 2, Presenter 3, Presenter 4 &Presenter 5

Lab Group L2BxEECE 380 – Electrical Engineering Design Studio (Spring 2014)

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Device Requirements and Problem Definition

•Custom built spectrum analyzer– 80Mhz-120Mhz frequency

range– 0dBm to -40dBm power

range– Selectable resolution

bandwidth•Provide a basis for FM signal analysis

– Modulation index– Modulation type– Carrier frequency

•Utilize given components and hierarchical block diagram •Construct additional subsystems •Implement supporting labVIEW system via myDAQ

– Collect data– Calculate data– Display data– Provide user interface

Requirements Defined Problem

Lab Group L2Bx

Design solution

EECE 380 - Electrical Engineering Design Studio (Spring 2014)

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X

VCO

Amplifier BP FilterMixer

Switch

Amplifier Crystal Filter Peak Detector

myDAQ

Amplifier Crystal Filter Peak Detector

RF input

Lab Group L2Bx

Hardware Implementation

• PCB – Complete system on single board– Precision IC peak detectors (-40dBm)– 0dBm to -65dBm power range

(estimated)– Time and money constraints

• Prototype board– Diode-based peak detection (-25dBm)– UBC switch PCB

EECE 380 - Electrical Engineering Design Studio (Spring 2014)

4

Lab Group L2Bx

Software Implementation

• Calibrated measurement calculation for peak detectors

• Graphic User Interface for spectrum display and resolution bandwidth selection

• Error correction and dynamic data acquisition based on GUI input

EECE 380 - Electrical Engineering Design Studio (Spring 2014)

5

Lab Group L2Bx

Results and Observations

• -5dBm to -40dBm power range

– <15% error

• 86Mhz to 120Mhz frequency range

– <2% error

• Automatic FM calculation for modulation index

EECE 380 - Electrical Engineering Design Studio (Spring 2014)

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• Mixer-Crystal Ladder Feedback

• Inconsistent non-linear VCO curve

Lab Group L2Bx

Questions?

EECE 380 - Electrical Engineering Design Studio (Spring 2014)

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