- Carrier-to-noise ratio
telecommunications, the carrier-to-noise ratio, often written CNR or "C/N", is the signal-to-noise ratio(SNR) of a modulated signal. The CNR is the quotient between the average received modulated carrier power "C" and the average received noisepower "N" after the receiver filters. The aim of the term is to distinguish the CNR of the radio frequency passbandsignal from the SNR of an analogue base bandmessage signal after demodulation, for example an audio frequency analogue message signal. If this distinction is not necessary, the term SNR is often used instead of CNR, with the same definition.
High "C/N" ratios provide good quality of reception, for example low
bit error rate(BER) of a digital message signal, or high SNR of an analogue message signal.
"C" and "N" may be measured in watts or in volts squared.
where and are the
root mean squarevoltage levels in volts of the carrier signal and noise respectively. Engineers often specify the "C"/"N" ratio in decibels (dB) between the power in the carrier of the desired signal and the total received noise power, according to the following:
The "C/N" ratio is measured in a manner similar to the way the
signal-to-noise ratio("S"/"N") is measured, and both specifications give an indication of the quality of a communications channel.
In the famous
Shannon–Hartley theorem, the "C/N" ratio is equivalently to the "S"/"N" ratio.
The "C/N" ratio resembles the
carrier-to-interference ratio("C/I", CIR), and the carrier-to-noise-and-interference ratio, "C/(N+I)" or CNIR.
Signal-to-noise ratio(SNR or "S"/"N")
Carrier-to-interference ratio(CIR or "C"/"I")
Audio system measurements
Subjective video quality
Peak signal-to-noise ratio
SINAD(ratio of signal-plus-noise-plus-distortion to noise-plus-distortion)
Eb/N0(energy per bit relative to noise power spectral density)
Es/N0(energy per symbol relative to noise power spectral density)
Carrier-to-receiver noise density"C/"N"0
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