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Contents

Analog Communication

Amplitude Modulation

Amplitude Modulation Basics AM Frequency Spectrum AM Power Relations AM DSB-FC AM DSB-SC AM SSB VSB Modulation AM Modulators AM Demodulators Costas Loop

Frequency Modulation

FM Basics Bessel Functions in FM Carson's Rule PM Basics Narrowband FM Indirect FM Generation Direct FM Generation FM Demodulation Basics Foster-Seeley Discriminator Ratio Detector PLL Demodulator Pre-emphasis and De-emphasis Stereo FM

Noise Analysis

Noise Taxonomy Thermal Noise White Noise Signal to Noise Ratio Noise Figure Friis Formula Equivalent Noise Temperature Noise in AM Systems Noise in FM Systems FM Threshold Extension

Receiver Architectures

Receiver Parameters TRF Receiver Superheterodyne Receiver Image Frequency Rejection Double Conversion Direct Conversion Receiver Automatic Gain Control Tracking and Alignment

Pulse Modulation

Sampling Theorem Natural vs Flat Top Sampling PAM PWM PPM PCM Basics Quantization Noise Companding Delta Modulation Adaptive Delta Modulation DPCM

Analog vs Digital

Analog vs Digital Comm Hybrid Systems Applications Transition to Digital

Other Topics

Communication Channels Link Budget FDM TDM Television Basics

Other Subjects

Analog Electronics Digital Electronics Signals & Systems Control Systems Electromagnetic Theory Digital Communication Network Analysis Microprocessors VLSI Design Verilog HDL Power Electronics Embedded Systems DSP Electronic Devices

Section Progress20%

2 of 10 articles

Thermal Noise

Johnson-Nyquist noise voltage, bandwidth dependence.

Updated: 19 March 2026

5 min read

Thermal Noise Quiz

Test your understanding of Johnson-Nyquist noise, noise voltage calculations, and bandwidth dependence of thermal noise power.

Question 1 of 3

Q1.A resistor of value R = 1 kohm is at temperature T = 290 K. The RMS open-circuit thermal noise voltage across it over a bandwidth B = 1 MHz is (k = 1.38e-23 J/K):

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Noise in FM Systems

Figure of merit, capture effect, threshold effect.

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Noise in AM Systems

Figure of merit, coherent detection SNR.

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Noise Figure

Definition F, relation to noise temperature Te.

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Signal to Noise Ratio

Input SNR, Output SNR, SNR in dB.

5 min read

Equivalent Noise Temperature

System temperature, antenna temperature.

8 min read