Patent ID: 6909781

Claim:
An analog front end system, comprising: a digital-to-analog converter; a line driver, electrically coupled to said digital-to-analog converter; a hybrid, electrically coupled to said line driver; a multiple-input device having a plurality of inputs and at least one output, wherein at least one of said inputs is electrically coupled to said hybrid; an analog-to-digital converter, electrically coupled to said output of said multiple-input device; an isolation circuit configured to maintain direct-current isolation between the terminals of said isolation circuit, wherein: said isolation circuit is electrically coupled to at least one of said inputs of said multiple-input device; and said isolation circuit comprises a plurality of resistance elements and a plurality of capacitance elements, electrically coupled; a ground circuit configured to provide a ground reference, wherein: said ground circuit is electrically coupled to at least one of said inputs of said multiple-input device; and said ground circuit comprises a plurality of resistance elements and at least one ground reference point, electrically coupled; and a processing circuitry, said processing circuitry being configured to control said digital-to-analog converter, said line driver, said analog-to-digital converter, and said multiple-input device in response to commands received by said processing circuitry.