Patent ID: 8780340
Filing Date: 2014-07-15
Classification: G01M,H04B,H04Q

Abstract:
1. An optical time domain reflectometer (OTDR) test signal modulation circuit, comprising: a laser diode drive, a laser diode, a current adjusting unit, and an OTDR control unit; wherein the laser diode drive is connected to the laser diode, and is configured to drive the laser diode to transmit data light according to an input data signal; and the current adjusting unit is connected to the laser diode and the OTDR control unit, and is configured to adjust a current flowing through the laser diode according to an OTDR test signal provided by the OTDR control unit, so as to modulate the OTDR test signal to the data light transmitted by the laser diode, wherein the current adjusting unit comprises a first resistor, a controlled switch, and a second resistor; the first resistor, the controlled switch, and the second resistor are serially connected to form a series-connected branch circuit; a first connection end of the controlled switch is connected to the laser diode through the first resistor, a second connection end of the controlled switch is grounded through the second resistor, a control end of the controlled switch is connected to the OTDR control unit, and the controlled switch is configured to control an opening/closing status of the series-connected branch circuit according to the OTDR test signal provided by the OTDR control unit.