| 摘要 |
An in-line data protector for preventing a test set from accessing a telephone line under a predetermined condition is disclosed. The in-line data protector selectively connects the test set and the telephone line responsive to detection of a data signal on the telephone line. The in-line data protector includes a power circuit for providing general operating power, a processor connected to the telephone line, and a relay serially connected between the telephone line and the test set. When general operating power is received, the processor analyzes the telephone line by emulating a single band filter. By using a single band filter, a very good determination can be made as to whether a signal on the telephone line is a data signal or a voice signal. If the signal is not a data signal, the processor instructs the relay to close, thereby connecting the telephone line to the test set.
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