| 摘要 |
<p>PURPOSE:To increase the kinds of an access signal from an exchange to a terminal equipment by setting the kinds of a DC voltage supplied from the telephone exchange to the terminal equipment to other voltage value in addition to a conventional value -48V. CONSTITUTION:A voltage V0 is set to -48V and a voltage V1 is set to -24V by a voltage generator 6. In the case of turning off a loop switch 4, DC voltages supplied to a terminal equipment are set into two ways V0, V1 by a selector 7. When an ordinary state is V0(-48V), the voltage detector 5 of a terminal equipment 2 detects the voltage V1 to handle the V1 as access signal. Moreover, in using a conventional normal/reverse polarity inverting switch 3, two signals of V1, -V1 are added newly.</p> |
