A wideband spectrum analyser-synthesizer for the prediction and smoothing of interrupted speech

Time sharing of slowly-interrupted speech will be a possible alternative to the vocoder for increasing the capacity of a speech communication channel, if the associated switching noise can be eliminated. It has been shown that this noise can be suppressed by reiterating the interrupted speech samples at the receiver so that they fill in the blank spaces correctly both in time and in phase. A wideband phase advancing network for speech signals is required for such a coherent reiteration and a practical technique has been proposed for this purpose. The error inherent to prediction and the additional error introduced by the practical limitations of the proposed system have been estimated. The system described can help to increase the line capacity by a factor of two or four, or eight at the most. The wideband phase correction network described here is essentially a spectrum analyser-synthesizer and can be used for the analysis and synthesis of any quasi-time-invariant complex wave.