| 摘要 |
PROBLEM TO BE SOLVED: To provide a communication controller having a wider range for performing normal operation when the communication controller is installed under an environment where a call signal has nonstandard distortion and voltage amplitude. SOLUTION: The communication controller includes: a call signal detection circuit for detecting, as a call signal, line voltage that changes in a sinusoid shape at a predetermined cycle between a pair of lines of a communication line and outputting a first recognition signal in accordance with the detected call signal; a sampling part incorporated in a direct access arrangement (DAA) being a semiconductor element for line communication and for sampling the line voltage; a second recognition signal outputting part incorporated in the DAA and for sampling the call signal detection circuit to recognize a change in the line voltage and outputting a second recognition signal; a line voltage judging part for judging the waveform of the call signal on the basis of a result obtained by sampling the line voltage during an incoming call; and a detection control part for determining whether to use the first recognition signal or the second recognition signal to detect the call signal on the basis of a result obtained by causing the line voltage judging part to judge the waveform during incoming call in advance, and using the determined signal to detect subsequent call signals. COPYRIGHT: (C)2008,JPO&INPIT
|
