FM systems are far better at rejecting noise than AM systems. Noise generally is spread uniformly across the spectrum (the so-called white noise, meaning wide spectrum). The amplitude of the noise varies randomly at these frequencies. The change in amplitude can actually modulate the signal and be picked up in the AM system. As a result, AM systems are very sensitive to random noise. An example might be ignition system noise in your car. Special filters need to be installed to keep the interference out of your car radio.
FM systems are inherently immune to random noise. In order for the noise to interfere, it would have to modulate the frequency somehow. But the noise is distributed uniformly in frequency and varies mostly in amplitude. As a result, there is virtually no interference picked up in the FM receiver. FM is sometimes called "static free, " referring to its superior immunity to random noise.
Noise immunity is the ability of a system to perform even when there is noise present. The higher the level of noise a system can still operate under, the higher the noise immunity.
FM provides noise immunity, whereas AM is easily affected by noise. With FM, the amplitude of the sound is converted into a shift in frequency. So the volume is limited by the bandwidth, but the frequency of the sound can vary as much as it likes, giving a higher fidelity sound. Spikes induced on the signal usually affect the amplitude of the signal. The amplitude of an FM signal is not used in the demodulation process and is therefore immune to spikes in the signal. AM was first used in radio because it is very easy to achieve using basic components. A single rectifier only, is needed to recover the audio. FM is quite a complicated process and could only be achieved once electronics had progressed.
In Frequency Modulation (FM), bandwidth is allocated based on the modulation index, which is determined by the frequency deviation of the carrier signal and the frequency of the modulating signal. According to Carson's Rule, the total FM bandwidth is approximately twice the sum of the maximum frequency deviation and the maximum frequency of the modulating signal. This means that FM signals can occupy a wider bandwidth compared to Amplitude Modulation (AM), allowing for better noise immunity and audio quality. Typically, for standard FM broadcasting, the bandwidth is around 200 kHz.
LNA - Low Noise Amplifier
limiter mainly used to limit the amplitude of FM waveform.because of, in FM the frequency only varied but amplitude also varied due to noise . to cancel the amplitude variation limiter mainly used
FM immunity, or Frequency Modulation immunity, refers to the ability of a receiver or communication system to maintain performance and reject interference despite variations in frequency. This is crucial in environments with potential signal distortion or noise, as FM signals can be more resilient to such disruptions compared to amplitude-modulated signals. Enhanced FM immunity allows for clearer communication and improved reliability in various applications, including radio broadcasting and wireless communication systems.
Noise immunity is the ability of a system to perform even when there is noise present. The higher the level of noise a system can still operate under, the higher the noise immunity.
FM provides noise immunity, whereas AM is easily affected by noise. With FM, the amplitude of the sound is converted into a shift in frequency. So the volume is limited by the bandwidth, but the frequency of the sound can vary as much as it likes, giving a higher fidelity sound. Spikes induced on the signal usually affect the amplitude of the signal. The amplitude of an FM signal is not used in the demodulation process and is therefore immune to spikes in the signal. AM was first used in radio because it is very easy to achieve using basic components. A single rectifier only, is needed to recover the audio. FM is quite a complicated process and could only be achieved once electronics had progressed.
An important aspect of analogue FM satellite systems is FM threshold effect. In FM systems where the signal level is well above noise received carrier-to-noise ratio and demodulated signal-to-noise ratio are related by: The expression however does not apply when the carrier-to-noise ratio decreases below a certain point. Below this critical point the signal-to-noise ratio decreases significantly. This is known as the FM threshold effect (FM threshold is usually defined as the carrier-to-noise ratio at which the demodulated signal-to-noise ratio fall 1 dB below the linear relationship given in Eqn 9. It generally is considered to occur at about 10 dB).
Nature creates AM noise (static) so FM is clearer
Noise triangle is a triangular noise distribution for FM.Noise triangle is the study of effect of noise on the carrier signal of the FM wave.
Frequency Modulation (FM) is more resistant to noise than Amplitude Modulation (AM) because FM encodes information in the frequency variations of the carrier wave, rather than in its amplitude. Noise typically affects amplitude, leading to distortion in AM signals. Since FM signals are less dependent on amplitude, they can maintain their integrity even in the presence of noise, allowing for clearer reception. Additionally, FM receivers can utilize techniques like capture effect and limiting, further enhancing their ability to suppress noise and interference.
In Frequency Modulation (FM), bandwidth is allocated based on the modulation index, which is determined by the frequency deviation of the carrier signal and the frequency of the modulating signal. According to Carson's Rule, the total FM bandwidth is approximately twice the sum of the maximum frequency deviation and the maximum frequency of the modulating signal. This means that FM signals can occupy a wider bandwidth compared to Amplitude Modulation (AM), allowing for better noise immunity and audio quality. Typically, for standard FM broadcasting, the bandwidth is around 200 kHz.
The abbreviations FM and AM stands for amplitude modulation and frequency modulation. The reason why FM is more clearer than AM is because FM has a better signal-to-noise ratio than AM does.
Noise margin refers to the difference between the actual voltage levels of a digital signal and the threshold levels required for reliable recognition of logic states, providing a buffer against noise interference. Noise immunity, on the other hand, is the ability of a system to withstand external noise without affecting its performance or accuracy. Together, they are crucial in ensuring reliable digital communication and signal integrity in electronic circuits, especially in environments with potential electromagnetic interference. High noise margins and strong noise immunity enhance a system's robustness against disturbances.
Fransisco Pizarro had superior weapons, and the Incas had no immunity against diseases
LNA - Low Noise Amplifier