Radio 6.111Slide2Slide3Analog ModulesBandpass FilterAnalog to Digital ConverterSlide8Digital ComponentsThe Hard PartTuningAdjusting StationsOscillatorExpected IssuesProposed SolutionsMilestonesRadio 6.111Dexter ChanThis watermark does not appear in the registered version - http://www.clicktoconvert.comlabkitThis watermark does not appear in the registered version - http://www.clicktoconvert.comThis watermark does not appear in the registered version - http://www.clicktoconvert.comAnalog Modules•Antenna, amplifier–Schematic from techlib.comThis watermark does not appear in the registered version - http://www.clicktoconvert.comBandpass Filter• Built from one op-amp• Tune resistors, capacitors as appropriateR1 * C1 >> 5.8 * 10^-7R2 * C2 << 1.8 * 10^-3http://www.swarthmore.edu/NatSci/echeeve1/Ref/FilterBkgrnd/Filters.htmlThis watermark does not appear in the registered version - http://www.clicktoconvert.comAnalog to Digital Converter• Requirements:–At least 4 MSPS, preferably 8 to 10–Ideally 20-bit resolution—quantization noise–Architectures? Can this be done on FPGA?• Options:–AD7621: $29.95, 3 MSPS, 16-bit–AD7760: $34.95, 2.5 MSPS, 24-bit–LTC2202: $30.00, 25 MSPS, 16-bitThis watermark does not appear in the registered version - http://www.clicktoconvert.comThis watermark does not appear in the registered version - http://www.clicktoconvert.comDigital Components• Synchronizer–Sequential bits arrive on sequential cycles from ADC–Depends on ADC architecture• FFT/Inverse FFT–Modules exist in VerilogThis watermark does not appear in the registered version - http://www.clicktoconvert.comThe Hard Part• Tuning and Modulation• Theory: –AM transmission—carrier wave multiplied by signalThen, y(t) = x(t) •cos(wot)=> Y(w) = X(w) •[d(w+ wo) + d(w-wo)]/ 2Generally, demodulate by multiplying by cosine, lowpassfilteringThis watermark does not appear in the registered version - http://www.clicktoconvert.comTuning• Need to recover main band, sidebands• To recover spectrum at given frequency, use a bandpassfilter• Bandpass filter needs to be 10 kHz wide, to recover sidebands and prevent aliasingThis watermark does not appear in the registered version - http://www.clicktoconvert.comAdjusting Stations• Inputs to tuner: up, down• Works like volume dial—UP shifts center of bandpass filter up by 10 kHz, DOWN shifts center down 10 kHz• Decoder sends control signal to oscillator This watermark does not appear in the registered version - http://www.clicktoconvert.comOscillator• Generates cos(wot) to recover signal •wocontrolled by user inputs—UP, DOWN• Multiply, lowpassfilter with bandwidth equal to 2x bandwidth of original signalThis watermark does not appear in the registered version - http://www.clicktoconvert.comExpected Issues• Spectral noise• ADC interface–Quantization noise—more resolution, sigma-delta architecture–Sigma-delta ADCs can’t sample fast enough–Power supply noise• Radio reception in the labThis watermark does not appear in the registered version - http://www.clicktoconvert.comProposed Solutions• Spectral Noise–Prefilter, preamplifystages–Small compared to quantization noise; can probably be ignored• Radio Reception in Lab–Test analog front end elsewhere—artificially generate AM signals to test digital hardware• ADC Issues…This watermark does not appear in the registered version - http://www.clicktoconvert.comMilestones• Tuner system testable by 11/28• Signal demodulation testable by 12/1• Analog Front End testable by 12/5This watermark does not appear in the registered version -
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