| 摘要 |
<p>The input and output of amplifier (110) are sampled and downconverted in frequency and filtered at (124 and 126) to produce sub-band signals. The input signal sub-band (134) is then subtracted from the output signal sub-band (136) at (130) to produce a residual signal (132) containing any distortion present in the sub-band selected by the downconversion oscillator (128). Signal analyser (158) compares the input and output signal energy to deduce the amount of distortion in the output signal, to provide signals for controlling a distortion reduction mechanism such as a predistorter operating on amplifier (110). Alternatively, the input signal sub-band (134) and the output signal sub-band (136) are Fourier transformed (210 and 212) to produce spectrums which can be analysed to determine the presence of distortion in the output of amplifier (110).</p> |
