| 摘要 |
PURPOSE:To discriminate and select an effective clock to a network terminator automatically by discriminating a reception signal waveform from an ISDN line network. CONSTITUTION:After a network terminator sends an INFO2 and all terminal equipments send an INFO3, the edge signal interval by an edge detection circuit 2 ts measured by a counter circuit 3, and a pulse length comparator, 4 compares the measured value (pulse width) with the standard pulse width to discriminate the wiring form of the basic interface of the ISDN line network. Thus, the clock selection signal is generated and a fixed clock or a retiming clock is selected surely and automatically. |
