Software-Based Ring/LIU/PPU Detection


This application note describes how to implement ring, line-in-use (LIU), and parallel pickup (PPU) functions using the Teridian \"energy detect\" software. This method, used with the Teridian 73M1903 and 73M1903C modem analog front-ends (AFEs), reduces the overall bill-of-material (BOM) cost associated with implementing embedded soft modems. Fundamental to the technique is the utilization of three system resources: constant analog caller ID signal path, digital signal processing in host, and the 73M1903 and 73M1903C's internal dedicated signal boost capability. Read full article.