Carrier
Understanding Carrier
The carrier wave provides the transport mechanism for information in RF communications. Modulation impresses data onto the carrier by varying its amplitude (AM), frequency (FM), phase (PM), or combinations thereof (QAM). The carrier frequency determines propagation characteristics and regulatory requirements.
In digital communications, the carrier is generated by a local oscillator and modulated using I/Q modulators. Carrier frequency stability, phase noise, and spectral purity directly impact system performance and adjacent channel interference.
Frequently Asked Questions
What determines the carrier frequency?
Carrier frequency is determined by spectrum allocation, propagation requirements, antenna size constraints, and regulatory licensing for the intended application.
What is carrier-to-noise ratio?
C/N ratio measures the carrier signal power relative to the noise power in the channel bandwidth, determining the achievable data rate and error performance.