In a perfectly linear electrical system with multiple carrier frequencies, though "linear distortion
" of power levels may occur, no additional frequencies can be generated.
In fact, the linear distortion
of Figure 3(a) could be easily filtered out by an average digital filter, but the DC shift in Figure 3(b) is not easy to be compensated.
(4) Circuit stages:In nonlinear compensation technology, because the linear distortion
and nonlinear distortion tend to gradually compensate for each other over long-distance transmission lines, the same circuit must be designed so that it has multiple stages of serial connections.
Peak clipping is fundamentally a non linear distortion
. It is characterized by the fact that several successive values of the signal disappear and are replaced by a constant.
This channel model represents common distortions in a standard single-mode fiber (SMF) suffering from a linear distortion
such as CD or the first order PMD when the dominant noise component is the amplified spontaneous emission (ASE) noise, which is modeled as an additive white Gaussian noise (AWGN).
In this model, the linear distortion
effects (such as filtering) are separated from the nonlinear distortion effects.
Kenington, "Linear Distortion
Correction Using a Feedforward System," IEEE Transactions on Vehicular Tech., Vol.
By calibrating the DCR the linear distortion
of the receiver can be characterized and eliminated from the signal measurement.
The linear distortion
component is due to deviations of the amplifier's frequency response from flat gain and linear phase. Note that distortion from memory effects also can be compensated using the feedforward technique since these effects are included in the error signal.
Impairment types can be divided into linear distortion
effects, for example, carrier leakage, I/Q imbalance and quadrature offset, and nonlinear distortion effects, such as AM-to-AM and AM-to-PM noise caused by harmonics and oscillator phase noise.