Wireless CommunicationsLab Tour

Dr. Bradley J. BazuinAssistant Professor

Department of Electrical and Computer EngineeringCollege of Engineering and Applied Sciences

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Radio Receiver Historical Progress• All Analog

• Digital Demodulation

tf2cos 1LO

tx c

Bandpass Filter

tf2cos 2LO

nxBB

Amplifier Lowpass Filter

Bandpass Filter

Tuning

tx eDPr

ADC

tf2cos 1LO

tx c

Bandpass Filter

tf2cos 2LO

tx M

Amplifier Lowpass Filter

Demod

Bandpass Filter

Tuning

tx eDPr

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RF Receiver Historical Progress (2)• IF Sampling Receiver – 1st Generation Software Defined

Radio

• All-Digital Receiver – Software Defined Radios tf2cos 1LO

tx c

Bandpass Filter

nxIF

AmplifierBandpass Filter

Tuning

tx eDPr

ADC

tx c nxRF tx eDPr

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Digital Data Communications System• Format: making the message compatible with digital processing• Source Coding: efficient descriptions of information sources• Channel Coding: signal transformation enabling improved reception

performance after expected channel impairments• Modulation: formation of the baseband waveform• RF Mixing: frequency domain translation of baseband signal• Transmit/Receive: RF Amplifiers and Filters

Information Message Format Source

EncodeMod-

ulation RF Mixing Transmitter

Reformat Source Decode

Demod-ulation RF Mixing Receiver

Antenna

AntennaInformation Message

RF Signal

Noise

Interference

Channel Encode

Channel Decode

Bits Symbols Signals

Signal Processing Functions:Applied DSP

5Notes and figures are based on or taken from materials in the course textbook:

Bernard Sklar, Digital Communications, Fundamentals and Applications, Prentice Hall PTR, Second Edition, 2001.

Smart Phone: Software Defined Radio

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USRP Based Software Radio

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USRP – RF Receiver/Transmitter and ADC/DAC

• Ettus Research – A wholly owned subsidiary of National Instruments - http://www.ettus.com/

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RF Daughter boards and Units

• USRP N210, nom. 100 MS/s, 1 Gb Ethernet, Spartan 3A_DSP Xilinx• USRP B100, nom. 64 MS/s, USB 2.0

• LFRX Daughterboard 0-30 MHz Rx• LFTX Daughterboard 0-30 MHz Tx• BasicTX Daughterboard 1-250 MHz Tx• BasicRX Daughterboard 1-250 MHz Rx• SBX 400-4400 MHz Rx/Tx (40 MHz)

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GNU Radio – The PC Software

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GNU Radio Companion - Tool

• Interconnecting building blocks to make radios– Sources– Sinks– Filters– Demodulators– Scopes– Spectrum Analyzers– Math Functions

• Or Custom Software– Python and C++

11from: http://www.csun.edu/~skatz/katzpage/sdr_project/sdr/grc_tutorial1.pdf

Lab Communications Test Systems

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RF Spectrum Analyzers

• Hewlett Packard/Agilent/Keysight4396B 100 kHz to 1.8 GHz– includes network analyzer (frequency reference source allows

output measurement of gain and phase changes)– generate a filter Bode Plot– Observe and analyze signal spectra

• Tektronix Real-Time Spectrum Analyzer up to 3 GHz– FFT based , limited bandwidth– Acquire I,Q samples of data triggered by spectral activity.

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