Adjacent Channel Power Ratio (ACPR) is
ratio
In mathematics, a ratio shows how many times one number contains another. For example, if there are eight oranges and six lemons in a bowl of fruit, then the ratio of oranges to lemons is eight to six (that is, 8:6, which is equivalent to the ...
between the total power of
adjacent channel
In broadcast
Broadcasting is the distribution (business), distribution of sound, audio or video content to a dispersed audience via any electronic medium (communication), mass communications medium, but typically one using the electromagnetic ...
(
intermodulation
Intermodulation (IM) or intermodulation distortion (IMD) is the amplitude modulation of signals containing two or more different frequencies, caused by nonlinearities or time variance in a system. The intermodulation between frequency com ...
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' ...
) to the main channel's power (useful signal).
Ratio
The ratio between the total power adjacent channel (intermodulation signal) to the main channel's power (useful signal). There are two ways of measuring ACPR. The first way is by finding 10*log of the ratio of the total output
power
Power most often refers to:
* Power (physics), meaning "rate of doing work"
** Engine power, the power put out by an engine
** Electric power
* Power (social and political), the ability to influence people or events
** Abusive power
Power may ...
to the power in adjacent channel. The second (and much more popular method) is to find the ratio of the output power in a smaller bandwidth around the center of carrier to the power in the adjacent channel. The smaller bandwidth is equal to the
bandwidth of the adjacent channel signal. Second way is more popular, because it can be measured easily.
ACPR is desired to be as low as possible. A high ACPR indicates that significant spectral spreading has occurred.
See also
*
Spectral leakage
The Fourier transform of a function of time, s(t), is a complex-valued function of frequency, S(f), often referred to as a frequency spectrum. Any linear time-invariant operation on s(t) produces a new spectrum of the form H(f)•S(f), which cha ...
*
Spread spectrum
In telecommunication and radio communication, spread-spectrum techniques are methods by which a signal (e.g., an electrical, electromagnetic, or acoustic signal) generated with a particular bandwidth is deliberately spread in the frequency dom ...
References
Power electronics
Signal processing
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