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
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