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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
3
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
4
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.
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 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
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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