HB3YAQLucerne
Thermal noise
Noise power from temperature, bandwidth and noise figure.
HB3YAQ · Ajdin HadzicLearning to take awayhttps://hb3yaq.ch/en/tools/noise-floor
View saved items →Only in this browser
Loading calculator …
Formula & context
N = kB · B · [T + 290 · (10^(NF/10) − 1)]
The source contributes kBTB. Receiver noise figure is converted at the 290 K reference into an equivalent added noise temperature, keeping the model consistent for other source temperatures.
A worked example
At 290 K with an ideal receiver, 1 Hz gives about −173.98 dBm. Ten times the bandwidth adds 10 dB of noise power.
Assumptions & limits
Use equivalent noise bandwidth. Atmospheric and local interference, ADC limitations and other receiver stages are excluded.
Noise, bandwidth and sensitivityUnderstand the reasoning →From reading to experimenting
Thermal noise
At 290 K with an ideal receiver, 1 Hz gives about −173.98 dBm. Ten times the bandwidth adds 10 dB of noise power.
Open example with starting values →Noise bandwidth: 1 Hz · Temperature: 290 K · Noise figure at 290 K: 0 dBBack to the learning article →Then change exactly one value. Compare the result and use the formula to explain why it changes. The model limits below the calculator also apply here.