Fundamentals of Electrical Noise

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Fundamentals of Electrical Noise by Kurt Stern Jan 2004 1 WhiteWhite NoiseNoise • In 1928 Johnson and Nyquist ID the Problem • Nyquists Theorem P = KTB P = Noise Band power in Watts T = Temp Degree Kelvin (T) K = Boltzmans Constant 1.38X10-23 B = Bandwidth (Hertz) 2 Excess Noise Ratio in dB ENR=10Log((T/290)-1) T in Kelvin is the temperature of a resistor 3 NoiseNoise GeneratingGenerating DevicesDevices 4 NoiseNoise EquivalencyEquivalency ReferenceReference ChartChart 5 ApplicationsApplications ofof NoiseNoise TechnologyTechnology • Measure Noise Figure • Gain and Bandwidth Parameters • Susceptibility to External Interference • Jamming • System Self Test 6 NoiseNoise MeasurementsMeasurements • The Radiometer • Noise Standards • Calibration of Noise Standards • Errors in Noise Measurements 7 BasicBasic SwitchingSwitching RadiometerRadiometer 8 Simplified Automate Radiometer 9 NISTNIST AutomatedAutomated RadiometerRadiometer 10 NBSNBS SwitchingSwitching RadiometerRadiometer 11 CommercialCommercial SwitchingSwitching RadiometerRadiometer 12 CommercialCommercial SwitchingSwitching RadiometerRadiometer (Specifications for the PRD 915-B Attenuation Calibrator) 13 Noise Figure Measurements • Y Factor • Twice Power Measurements • Automatic Measurements • Noise Figure to Temperature 14 Y Factor 15 Twice Power NF Measurement 16 17 Noise Figure vs. Noise Temperature Conversion Chart 18 ENR Measurement VSWR Error 19 20 Noise Source UUT VSWR Error 21 AutomaticAutomatic NoiseNoise FigureFigure MeterMeter 22 Noise Figure Equivalence Chart 23 ApplicationsApplications byby IndustryIndustry • Military • Electronics Manufacturing • Communications 24 Noise Standards • Characteristics - Flat Power Spectrum - High Degree of Stability • 3 Classes - Noise Diodes - Gas-Discharge Tubes - Thermal Noise Sources 25 Generation of Noise 26 Thermal Noise Calculation 27 Avalanche Noise Region 28 Vacuum Diode Noise Source 29 High Temperature Noise Standard 30 Low Temperature Noise Standard 31 Low Temperature Thermal Conductivity 32 Error Flow Diagram 33 DUT Noise Temperature Errors 34 USA-England Intercomparison 35 USA-Sweden Intercomparison 36 NoiseNoise AmplificationAmplification • Bandwidth Power • Crest Factor 37 CrestCrest FactorFactor (CF)(CF) 38 Gaussian NoiseNoise DistributionDistribution 39 Amplifier Bandwidth & Power • Noise Power = Unit noise power X bandwidth • Consequently for some designs wider bandwidths may require a higher compression point amplifier 40 Communications Systems Testing • White Noise Testing • Bit Error Rate vs. Noise 41 WhiteWhite NoiseNoise TestingTesting 42 WhiteWhite NoiseNoise TestTest EquipmentEquipment • Noise Generator • Noise Receiver 43 44 ATMATM NoiseNoise SourcesSources (Z(Z Model)Model) 45 ATMATM NoiseNoise SourceSource (Y(Y Model)Model) 46 47 48 49 Thank You 50.

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Noise Tutorial Part V ~ Noise Factor Measurements Whitham D. Reeve Anchorage, Alaska USA See last page for document information Noise Tutorial V ~ Noise Factor Measurements Abstract: With the exception of some solar radio bursts, the extraterrestrial emissions received on Earth’s surface are very weak. Noise places a limit on the minimum detection capabilities of a radio telescope and may mask or corrupt these weak emissions. An understanding of noise and its measurement will help observers minimize its effects. This paper is a tutorial and includes six parts. Table of Contents Page Part I ~ Noise Concepts 1-1 Introduction 1-2 Basic noise sources 1-3 Noise amplitude 1-4 References Part II ~ Additional Noise Concepts 2-1 Noise spectrum 2-2 Noise bandwidth 2-3 Noise temperature 2-4 Noise power 2-5 Combinations of noisy resistors 2-6 References Part III ~ Attenuator and Amplifier Noise 3-1 Attenuation effects on noise temperature 3-2 Amplifier noise 3-3 Cascaded amplifiers 3-4 References Part IV ~ Noise Factor 4-1 Noise factor and noise figure 4-2 Noise factor of cascaded devices 4-3 References Part V ~ Noise Measurements Concepts 5-1 General considerations 5-1 5-2 Noise factor measurements with the Y-factor method 5-6 5-3 References 5-8 Part VI ~ Noise Measurements with a Spectrum Analyzer 6-1 Noise factor measurements with a spectrum analyzer 6-2 References See last page for document information Noise Tutorial V ~ Noise Factor Measurements Part V ~ Noise Factor Measurements 5-1. General considerations Noise factor is an important measurement for amplifiers used in low noise applications such as radio telescopes and radar and other radio receivers designed to detect very low signal levels.
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