In adaptive
high-frequency
High frequency (HF) is the ITU designation for the range of radio frequency electromagnetic waves (radio waves) between 3 and 30 megahertz (MHz). It is also known as the decameter band or decameter wave as its wavelengths range from one to te ...
(HF)
radio
Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transm ...
, link quality analysis (LQA) is the overall process by which measurements of
signal
In signal processing, a signal is a function that conveys information about a phenomenon. Any quantity that can vary over space or time can be used as a signal to share messages between observers. The '' IEEE Transactions on Signal Processing' ...
quality are made, assessed, and analyzed.
In LQA, signal quality is determined by measuring, assessing, and analyzing
link parameters, such as
bit error ratio
In digital transmission, the number of bit errors is the number of received bits of a data stream over a communication channel that have been altered due to noise, interference, distortion or bit synchronization errors.
The bit error rate (BER ...
(BER), and the levels of the ratio of signal-plus-
noise
Noise is unwanted sound considered unpleasant, loud or disruptive to hearing. From a physics standpoint, there is no distinction between noise and desired sound, as both are vibrations through a medium, such as air or water. The difference aris ...
-plus-
distortion
In signal processing, distortion is the alteration of the original shape (or other characteristic) of a signal. In communications and electronics it means the alteration of the waveform of an information-bearing signal, such as an audio s ...
to noise-plus-distortion (
SINAD
Signal-to-noise and distortion ratio (SINAD) is a measure of the quality of a signal from a communications device, often defined as
:
\mathrm = \frac,
where P is the average power of the signal, noise and distortion components. SINAD is usually ex ...
). Measurements are stored at—and exchanged between—stations, for use in making decisions about link establishment.
For adaptive HF radio, LQA is automatically performed and is usually based on analyses of pseudo-BERs and SINAD readings.
References
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Radio technology
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