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).

SINR - Signal to Interference and Noise Ratio CINR - Carrier to Interference and Noise Ratio difference between those to is difference between carrier and signal carrier is signal who doesn't "carry" any information . it must be modulated( by phase,freq or amplitude) and those changes convey information. carrier is unmodulated signal signal is defined as useful signal which carries information SINR is power of signal to power of interfenence and noise ratio

Signal to noise ratio is a measure of signal strength to the background noise. Engineers use the signal to noise ratio to improve digital signal processing.

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.

for more details contact -Ameya Muley (amymuley@rediffmail.com)

Carrier to Interference plus Noise Ratio, it's a measure of "true" signal strength at a receiver. In SNR, simply the signal strength to noise is measured; in CINR, distortions caused by interference patterns is also taken into account.