The noise source of radar systems mainly includes thermal noise, which arises from the random thermal movement of electrons in electronic components such as amplifiers and resistors. This noise, also known as thermal noise or Johnson-Nyquist noise, is present in all electronic devices and increases with temperature. It contributes to the overall noise floor of the radar system, affecting its sensitivity and detection of weak signals.
The noise figure in radar refers to a measure of how much noise a radar receiver introduces into a signal compared to an ideal noisy receiver. It quantifies signal-to-noise ratio (SNR) degradation due to internal receiver noise. A lower noise figure indicates better receiver performance, because it means less additional noise added to the received signal during the amplification and processing stages.
A radar emits sounds that can be described as electronic chirps or pulses. These pulses are typically short bursts of radio frequency energy transmitted through the atmosphere. The sound produced by radar pulses depends on the operational frequency, pulse duration and modulation characteristics of the radar. For example, radar pulses may be heard as rapid clicking sounds when viewed on a spectrum analyzer or demodulated using appropriate equipment.
Receiver noise in radar systems refers to the inherent electronic noise present in the radar receiver itself. This noise includes thermal noise from electronic components like amplifiers and mixers, as well as other sources such as noise from shooting semiconductor junctions. Receiver noise reduces the SNR of the received signal, affecting the radar’s ability to accurately detect and measure targets, particularly at longer ranges or in environments with high background noise levels.
Thermal noise in radar is synonymous with Johnson-Nyquist noise, resulting from thermal agitation of charge carriers (electrons) in conductive materials in radar electronics. It is directly proportional to temperature and bandwidth, meaning that higher temperatures or wider bandwidths result in increased thermal noise levels. In radar systems, thermal noise contributes significantly to the overall system noise floor, impacting sensitivity and the ability to effectively detect weak radar returns.