Method and apparatus for feedback suppression

A method for suppressing positive feedback in a bidirectional communications unit having an incoming channel and an outgoing channel commonly coupled to a bidirectional coupling device and a voltage control gain block in one of said channels, said method comprising the steps of:

• a. time domain processing variable amplitude electrical signals in the other of said channels to attenuate preselected frequency components which promote said positive feedback;
• b. reconverting the signals resulting from step (a) to signals having a smoothly varying amplitude form;
• c. generating gain control signals from said signals in said other of said channels;
• and
• d. coupling said gain control signals to said voltage control gain block in said one of said channels to control the gain thereof.

A method for suppressing positive feedback in a bidirectional communications unit having an incoming channel and an outgoing channel commonly coupled to a bidirectional coupling device, said method comprising the steps of:

• a. time domain processing variable amplitude electrical signals in said incoming channel to attenuate preselected frequency components which promote said positive feedback;
• b. reconverting the signals resulting from step (a) to signals having a smoothly varying amplitude form;
• c. time domain processing variable amplitude electrical signals in said outgoing channel to attentuate preselected frequency components which promote said positive feedback;
• and
• d. reconverting the signals resulting from step (c) to signals having a smoothly varying amplitude form.

A sound amplification system having positive feedback suppression, said system comprising:

• a. means for generating variable amplitude electrical signals representative of acoustical signals lying in the audible range;
• b. means for time domain processing said electrical signals to attenuate therefrom preselected frequency components which promote positive feedback;
• and
• c. means for reconverting said processed signals to signals having a smoothly varying amplitude form.

A bidirectional communications unit operable in full duplex mode and having position feedback suppression, said unit comprising:

• a. a bidirectional coupling device providing an input/output signal port for said communications unit;
• b. an incoming signal amplifying channel for amplifying incoming variable amplitude signals coupled thereto from said coupling device, said incoming signal amplifier channel including means for time domain processing said variable amplitude signals to attenuate preselected frequency components which promote positive feedback and means for reconverting the time domain processed signals to signals having a smoothly varying amplitude form;
• c. an outgoing signal amplifier channel for amplifying variable amplitude signal representative of acoustic signals lying in the audible range, said output signal amplifier channel including a voltage gain block having a signal input, a signal output coupled to said coupling device, and a gain control input;
• and
• d. means having an input coupled to said incoming signal amplifier channel for generating gain control signals from signals in said incoming signal amplifying channel and an output coupled to said gain control input of said voltage control gain block.

A bidirectional full duplex communications unit having positive feedback suppression, said unit comprising:

• a. a bidirectional coupling device providing an input/output signal port for said communications unit;
• b. an incoming signal amplifier channel for amplifying incoming variable amplitude signals coupled thereto from said coupling device, said incoming signal amplifier channel including first means for time domain processing said incoming signals to attenuate therefrom preselected frequency components which promote positive feedback;
• and
• c. an outgoing signal amplifier channel for amplifying variable amplitude signals representative of acoustic signals lying in the audible range, said outgoing signal amplifier channel including second means for time domain processing said outgoing signals to attenuate preselected frequency components therefrom;
• said incoming and said outgoing signal amplifier channels each including means for reconverting the signals from said first and second means, respectively, to signals having a smoothly varying amplitude form.