A DSP-based microcomputer system for echo measurement in telephone networks

A schematic design is presented for a stand-alone test device to measure all aspects of echo at the subscriber location of dial lines in telephone networks. The proposed architecture is based on off-the-shelf components such as a general purpose PC and one of the available digital signal processing (DSP) boards with minimum additional hardware. Echo aspects are identified for measurements and the firmware (both hardware and software) of the design are presented. Although specific hardware components are chosen in the proposed system, the strategy of the design can account for different components. The system is tested in the laboratory using a telephone channel simulator under different conditions. It is also used in real telephone circuits. Samples of testing results are included.