Patent ID: 7787386

Claim:
A method comprising: providing a line card having: a digital signal processor for manipulating data received by the line card; a transmit channel and a receive channel coupled to a combined transmit and receive channel, the combined transmit and receive channel for transmitting and receiving communications with the line card; wherein the transmit channel comprises a first amplifier for amplifying a signal in the transmit signal and the receive channel comprises a second amplifier for amplifying a signal in the receive channel; one or more electrical components in the combined channel; a switch disposed in the combined channel; terminating the combined channel with a termination network, the termination network having a desired impedance; transmitting a test signal through at least a portion of the transmit channel toward the combined channel; determining whether any filters in the transmit channel or receive channel are malfunctioning by detecting, by the digital signal processor, any resulting signal in the receive channel; wherein the desired impedance is approximately equal to a characteristic impedance of a communication line conventionally used with the line card; and wherein the characteristic impedance is 100 ohms.