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noisebasic

Thermal Noise Power

#noise#thermal noise#johnson noise#noise floor#sensitivity

Thermal Noise Power

Thermal noise (also called Johnson-Nyquist noise) sets the fundamental limit for receiver sensitivity. This formula calculates the noise power generated by thermal agitation of electrons in any resistive element at a given temperature.

Pn=kTBP_n = kTB

Alternative Forms

In dBm at Room Temperature
Pn=−174+10log⁡10(BHz)P_n = -174 + 10\log_{10}(B_{Hz})
Practical form for 290K reference temperature
Noise Voltage
Vn=4kTBRV_n = \sqrt{4kTBR}
RMS noise voltage across resistance R

Input Variables

K

Absolute temperature of the noise source(Range: 1 – 10000 K)

Hz

Noise bandwidth of the system(Range: 1 – 1000000000000 Hz)

Constants

k= 1.380649e-23J/K

Results

Noise Power (P_n)
—

📖 Example: Wi-Fi Channel Noise Floor

Calculate thermal noise in a 20 MHz Wi-Fi channel at room temperature

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