| 摘要 |
<p>An optical fibre modem comprises a light emitting diode transmitter (11) and a photodiode receiver (12) both energized by a power supply (13-20) arranged to draw required power solely from the electrical data transmit line. The photodiode in the receiver (12) is connected with substantially zero bias to minimize dark current flow and hence temperature dependent noise. A switch mode supply comprising a single stage regulator (17) driven by a CMOS oscillator (18) is used for the power supply. The modem described in the preferred embodiment meets the EIA RS 232-C and CCITT V24 standards. <IMAGE></p> |
