Adaptive echo cancellation used with echo suppression to reduce short and long duration echoes

An echo suppressor controller device in a base station unit, comprising:

• a hybrid connecting a two-wire loop to a four-wire loop, said hybrid having a first port for receiving a first transmit signal from a near-end source, a second port for outputting said first transmit signal to said two-wire loop and for receiving a second transmit signal from a far-end source, and a third port for outputting said second transmit signal to said two-wire loop, wherein an impedance mismatch between said two-wire loop and said four-wire loop results in reflection of said first transmit signal to said near-end source through said third port;
• an adder/subtracter having an addition input, a subtraction input connected to receive said output from said third port of said hybrid, and an output port for outputting a residual error signal;
• an adaptive balance filter having a first input port connected to receive said first transmit signal, a second input port connected to receive said residual error signal, an enable port, and an output port for outputting a balance signal based on a correlation determined therein between said first transmit signal and said residual error signal;
• a decorrelation controller having a first input port connected to receive said first transmit signal, a second input port connected to receive said residual error signal, and outputting a first control signal to said enable port of said adaptive balance filter to control adaptation by said adaptive balance filter based on a level of correlation of said first transmit signal and said residual error signal as determined by said decorrelation controller, and outputting a second control signal in reverse polarity to said first control signal;
• a first and second voice level detector respectively connected to receive said first transmit signal and said residual error signal, said first and second voice level detectors respectively outputting a first and second voice detection level;
• an echo suppressor controller having a first and second input respectively connected to said first and second voice level detectors, said echo suppressor controller having an enable input for receiving said second control signal, and outputting an echo suppression control signal according to said first and second voice detection levels respectively received from said first and second voice level detectors;
• and
• an echo suppressor having a first input port for receiving said echo suppression control signal, a second input port for receiving said residual error signal, and an output port for outputting an attenuated residual error signal according to an attenuation level as determined from said echo suppression control signal received from said echo suppression controller.