| 摘要 |
Apparatus for remotely supervising via a telephone line a device includes a sensor for sensing for a telephone ring signal from the telephone line. In response to the sensing of the ring signal there is generated an off-hook condition which causes the termination of the ring signal. In addition an indicator responsive to the sensor produce a melody continuously repeated with an interval between each transmitted melody. This repeated melody is transmitted to the telephone line for counting by the caller. In addition, within the apparatus, a counter counts the melodies as they are produced. A key memory connected to the counter and responsive to the telephone line is activated when a predetermined count has been counted by the counter and there is a voice signal on the line from the caller. The operation of this key memory alerts a control circuit for the reception of subsequent voice signals which permit the changing of state of a controlled device.
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