Carrier to noise ratio, also known as CNR and C/N is a signal-to-noise ratio of a modulated signal. In simple terms, it is a measure of the received carrier strength in relation to the strength of the noise received (Margaret Rouse, Search Networking, CARRIER-TO-NOISE RATIO (CNR OR C/N), n.d.).This is designed for data streams of communication systems used by a carrier or frequency of interest. High C/N ratios are preferred because they provide higher reception quality as well as better accuracy and reliability in communications. This ratio is responsible for determining the quality of the information transmitted and whether it can be retrieved. One of its most common uses is in satellite communications systems to align or point the receiving dish.
A carrier to noise generator is a device that measures the power level across frequency bands. It generates a carrier to noise ratio based on the average power across the band. They are mostly used by design, system and test engineers in the field of cellular, military and satellite communications. They offer an efficient and cost-effective method of obtaining an increasingly higher yield. This is enabled through the means of automated testing which gives better results thanks to repeatable and accurate settings of the carrier to noise generator.
Distinguished features of a Carrier to Noise Generator:
It provides fast and accurate test results
High carrier to noise ratio for better reception quality
The level of noise can be adjusted without interrupting the carrier path to the output
It provides a highly accurate carrier to noise ratio
Fast carrier to noise level set up time
A noise bandwidth that can be customized
Carrier path with low levels of distortion
Carrier to Noise Ratio and Generators: An Overview
Generally, companies use carrier to noise generators in a PXI format. They have unique characteristics such as adjustable noise levels and a low bit error rate (BER). A BER tester can run continuously during a test using various C/N levels. It can also be made faster by using a lesser set up time.
Carrier to noise ratio is distinguished from signal to noise ratio in that the term CNR is used while referring to the radio frequency passband signal; the range of wavelengths that pass through a filter. The term SNR denotes an analog baseband message signal after it has been demodulated. Modulation and demodulation refer to terms used in electronics and telecommunications. While modulation involves transmitted information by means of a carrier signal, demodulation is the extraction of the original information-transmitted signal from a carrier wave using an electronic circuit.
C/N Ratio vs S/N Ratio
However, both C/N ratio and S/N ratio are measured in a similar manner as the specifications indicate the quality of a channel of communication. The application of a carrier to noise ratio is the optimization of the receiver performance. It is vital that the estimation techniques for CNR have to be conducted in a timely manner. This is because it is more difficult to estimate the ratio of signal power to noise power than to measure the total power.
Carrier to noise generators is ideal for production testing, making them useful for applications such as BER testing on microwave links. With their unique and custom features, investing in a good carrier to noise generator is a good bet for companies in the communications industry.