Speech signal transmission systems utilizing a non-linear circuit in the base band channel

Claim 2

A speech signal transmission system for transmitting speech signals of a relatively narrow frequency band from a transmitting side to a receiving side over relatively narrow band transmission channels which comprises at the transmitting side: an input terminal for receiving speech signals; a first non-linear circuit connected to said input terminal for producing signals including pitch frequency components of the voiced signal in the speech signals which are not involved in the relatively narrow frequency band speech signals; a band pass filter connected to said non-linear circuit for producing base band signals including said pitch frequency components produced by said non-linear circuit and representative of the spectral fine structure of the speech signals; a vocoder channel analyzer connected to said input terminal for converting the speech signals into a plurality of band compressed signals representative of the spectral envelope of the speech signals; and which coMprises at the receiving side: a second non-linear circuit for receiving said base band signals to produce exciting signals; and a vocoder synthesizer for receiving said band compressed signals and said exciting signals to reproduce substantially the original speech signals.

Claim 3

A speech signal transmission system for transmitting speech signals of a relatively narrow frequency band from a transmitting side to a receiving side over relatively narrow band transmission channels which comprises at the transmitting side: an input terminal for receiving the speech signals; a first non-linear circuit connected to said input terminal for producing signals including pitch frequency components of the voiced signal in the speech signals which are not involved in the relatively narrow frequency band speech signals; a first band pass filter connected to said non-linear circuit and arranged to pass said pitch frequency components which are not involved in the speech signals for producing a portion of base band signals representative of the spectral fine structure of the speech signals; a second band pass filter connected to said input terminal for producing the remaining portion of said base band signals, the pass band of which is adjacent to that of said first band pass filter; adding means for adding the outputs of said first and second band pass filters; a vocoder channel analyzer for converting a portion of the speech signals having a frequency band above the pass band of said second band pass filter into a plurality of band compressed signals representative of the spectral envelope of the speech signals; and which comprises at the receiving side: a second non-linear circuit for receiving said base band signals from the transmitting side to produce exciting signals; a vocoder synthesizer for receiving said band compressed signals from the transmitting side and said exciting signals from said second non-linear circuit to produce said portion of said speech signals; a third band pass filter having the same pass band as said second band pass filter at the transmitting side, for receiving said base band signals from the transmitting side; and adding means for adding the outputs of said vocoder synthesizer and said third band pass filter to reproduce substantially the original speech signals.

Claim 4

A speech signal transmission system for transmitting speech signals of a relatively narrow frequency band from a transmitting side to a receiving side over relatively narrow band transmission channels which comprises at the transmitting side: an input terminal for receiving the speech signals; a first non-linear circuit connected to said input terminal for producing signals including pitch frequency components of the voiced signal in the speech signals which are not involved in the relatively narrow frequency band speech signals; a first band pass filter connected to said non-linear circuit and arranged to pass said pitch frequency components which are not involved in the speech signals for producing a portion of base band signals representative of the spectral fine structure of the speech signals; a second band pass filter connected to said input terminal for producing the remaining portion of said base band signals, the pass band of which is adjacent to that of said first band pass filter; adding means for adding the outputs of said first and second band pass filters; a vocoder channel analyzer for converting a portion of the speech signals having a frequency band above the pass band of said second band pass filter into a plurality of band compressed signals representative of the spectral envelope of the speech signals; and which comprises at the receiving side: a second non-linear circuit for receiving said base band signals from the transmitting side to produce exciting signals; a vocoder synthesizer for receiving said band compressed signals from the transmitting side and said exciting signals from said second non-linear circuit to produce said portion of said speech signals; a third band pass filter having the same pass band as said second band pass filter at the transmitting side, for receiving said base band signals from the transmitting side; and adding means for adding the outputs of said vocoder synthesizer and said third band pass filter to reproduce substantially the original speech signals.