| 摘要 |
An apparatus and method for blocking or disrupting data being transmitted over an analog telephone line, the method including detecting single-frequency carrier tones and then opening the line for a predetermined time to disrupt modem synchronization and thereby blocking or disrupting data transmission, and the apparatus including a line-sensing circuit, an operational amplifier acting as input stages to the line sensing circuit, means for detecting a single-frequency carrier tone on the line, a relay for disconnecting the line when a single-frequency tone is detected, and a switch for selecting the disconnect time period.
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