C/N
Pronunciation: C over N
Also written as: C/N — Carrier-to-Noise Ratio
The ratio of the received satellite carrier signal power to the total noise power in a specified bandwidth, expressed in decibels, used as the fundamental measure of link quality.
Full Definition
Carrier-to-Noise Ratio (C/N) is the ratio of the power of a received RF carrier signal to the power of the noise present in the receiving system's noise bandwidth, expressed in decibels (dB). It is the fundamental quality metric for a satellite link, directly determining whether a receiver can correctly demodulate and decode the transmitted information. C/N is computed from the link budget by combining the satellite's EIRP, free-space path loss, ground station G/T, and Boltzmann's constant. A related quantity, Eb/N0 (energy per bit to noise spectral density ratio), normalises C/N for the data rate and is used to specify demodulator performance thresholds. Editors must not conflate C/N with C/N0 (carrier-to-noise spectral density, in dBHz) or with SNR (signal-to-noise ratio), which is used in baseband contexts.
Usage
Usage note: Render as 'C/N' (with forward slash, no spaces). Distinguish from C/N0 (C over N-zero), which is carrier power to noise spectral density in dBHz, and from Eb/N0, which normalises for data rate. SNR is a baseband term and should not be used in RF link contexts.
In Context
- "The total C/N of 9.6 dB exceeded the demodulator's threshold of 7.2 dB, providing a comfortable 2.4 dB margin." — Link Budget Report
- "Editors should confirm whether a specification references C/N (in a fixed noise bandwidth) or C/N0 (noise spectral density), as the numerical values differ significantly." — Editorial Style Guide