| 摘要 |
<p>Compatible single sideband (CSSB) transmission system utilizing a three tone generator to develop the characteristic CSSB modulation of an electromagnetic energy carrier wave, i.e. a somewhat reduced level carrier, a full level single sideband, and a lower level second order sideband, with only nominal envelope distortion and within the narrow bandwidth restrictions commonly assigned to voice communication systems and the like. In one aspect, the invention accomplishes restriction of the bandwidth of the transmitted CSSB signal by conjunctively or alternatively using only the relatively low audio frequencies (frequencies below about one-half of the frequency span of the prescribed bandwidth) to modulate the CSSB generator and separately modulating a single sideband suppressed carrier (SSBSC) generator with the higher audio frequencies, then summating the respective generator outputs to provide the transmitted signal. As a result of this procedure, all audio frequencies within the allocated bandwidth are represented in the transmitted signal and the signal is nonetheless a highly acceptable CSSB type signal in that the relatively higher audio frequencies are normally relatively weak and incur relatively low envelope distortion and in that there are essentially no out-of-band spectral components in the transmitted signal.</p> |
