| 摘要 |
PURPOSE:To enable a test without forming a channel every time at the execution of test, by incorporating a test use multi-frequency signal generating circuit in a receiver and transmitting the test use multi-frequency signal for test. CONSTITUTION:When a channel assigned to a digital tone receiver 3 is vacant, a test use multi-frequency signal is inputted to the vacant channel from a test use multi-frequency signal generating circuit 10, the inputted test use multi- frequency signal is detected and it is collated with a preset comparison data for failure detection. Thus, at no calling, since the test is always performed, the test execution period is short and a failure can immediately be detected, if the failure takes place. |
