Answer: The debugging of cable TV optical transceiver should pay attention to the following aspects:

1) Correctly select the input level of the RF signal.

The RF drive level of the DFB optical transmitter directly determines the modulation degree of the optical transmitter, and also determines the value of C/N, CTB, and CSO. If the RF level added to the optical transmitter is too large, it will cause the m value of the optical modulation index to increase, which will deteriorate the nonlinear indicators of CTB and CSO, and will also cause overdrive of the DFB laser, resulting in a decrease in the output power of the optical transmitter; input If the level is too small, the optical modulation system will be reduced, so that the carrier-to-noise ratio index of the optical transmitter cannot meet the requirements. Therefore, the correct selection of the RF drive level is the key to ensuring various indicators of the optical fiber transmission network. Optical transmitters produced by different manufacturers require different RF drive levels, so the input RF level of the transmitter should be set according to the manufacturer's product manual. If the product manual only gives a certain range of level value (such as 75-85db), the RF value is determined according to the number of network transmission channels. If the transmission frequency N>40, the RF value is 76-78dB; if it is 30, the RF value is taken. 78-80dB; if 20, take the RF value of 80-83bB. If the product manual gives 75+10Lg60/N, first calculate the value of 10Lg60/N according to the number of network transmission channels N, and then add it to 75, such as N=35, then 10Lg60/N=2.34dB, 75+2.34=77.34 , take RF=78dB.

2) Optical jumpers are generally used for optical transmission of cable television signals, and FC/APC interfaces are generally used.

3) The optical power of the optical receiver end must meet its receiving index, generally the best value is 0 ~ -3dB, and the general effective range is 2 ~ -6dB.

4) When installing the optical connector, first wipe the optical transmitter output port and connecting plug with an alcohol cotton ball, then align the protruding edge of the optical fiber plug with the notch of the optical output port, and screw the screw to the end, not too tight or not. If it is too loose, make sure that the two plugs are aligned and in good contact.

5) Ensure that the optical transmitter has a continuous and uninterrupted normal power supply with stable voltage.

The laser components and photoelectric conversion modules of the optical transmitter should avoid the impact of instantaneous pulse current. Therefore, frequent switching must be avoided or reduced in use to ensure the service life of the laser.

6) Once the laser enters the working state, the human eye must not look directly at the light output port on the rear panel of the optical transmitter, so as to avoid the laser burning the retina of the human eye.

7) After turning on the power and starting to enter the normal working state (the upper edge light of the transmitter panel is on when it is working normally, and the alarm red light is on when it is not normal), press the TEST button on the front panel, look at the LCD screen, and check in sequence Status related to the operation of the laser.

8) Under the premise that the external power supply is normal, once the red light flashes or lights up after the optical transmitter is powered on or during operation, it means that the optical transmitter has malfunctioned, and the power supply should be cut off immediately, and it should be checked and maintained or returned to the factory for repair.