| 摘要 |
<p>A vestigial sideband (VSB) signal is demodulated by separately a.m. and f.m. demodulating the signal, triangulating the a.m. demodulated signal, i.e. processing the a.m. demodulated signal to produce an output whose magnitude is a function of the frequency of the a.m. demodulated signal, and combining the result with the f.m. demodulated signal; the output signal is substantially free from the usual distortion which arises due to the absent sideband. The same technique is used to suppress adjacent channel interference (ACI) affecting a signal on one side of its carrier frequency. ACI affecting a signal on both sides of its carrier frequency is suppressed as above in some cases if the polarity and/or magnitude of the triangulated a.m. demodulated signal is adjusted dependent upon the value of the f.m. demodulated signal. ACI is also reduced by filtering a signal to remove one sideband containing interference and then demodulating the filtered signal as a VSB signal by the above technique.</p> |
