If the link is unstable and packet loss is intermittent, it is probably because the light receiving power has dropped to the edge of sensitivity. It is not scary to have low light receiving, but the scary thing is to change the equipment based on your feelings. The inspection should be carried out in the order of testing first, then cleaning, and then review, so as to pin down the problem to the specific link.
Test the light emission and light collection first, and then decide whether to use the equipment or not.
Use an optical power meter to measure the light emitting and receiving light at both ends. The light emission of 100M and Gigabit single-mode transceivers is generally -10dBm to -3dBm; the 10-kilometer level light reception is lower than -20dBm, and the 40-kilometer level is lower than -26dBm, which is considered critical. At this time, there is usually no improvement when replacing new equipment with the same specifications, because the problem lies in the wiring rather than the machine itself. Measuring the number is the ticket to troubleshooting.
Three common sources of power loss
- Connector contamination: Dust and oil film cause a few tenths to several dB loss. Clean with alcohol cotton and re-plug and unplug twice before measuring again.
- Aging and bending of jumpers: Tightening of the coil causes macro-bending loss. Replace the confirmed one directly.LC-LC single mode dual core jumper, used in SC interface scenariosSC-SC single mode single core jumper.
- Welding and flange loss: Single-point welding generally does not exceed 0.1dB. If the movable connector is extremely dirty, the adapter must be cleaned or replaced.
Review with link budget to avoid long-term critical operation
The link budget is equal to the luminous power minus the light receiving sensitivity, leaving a 3dB system margin after deducting the joint and splice losses. Taking a 20-kilometer link as an example, the fiber attenuation is about 8dB at 0.4dB/km, plus two movable joints of 0.5dB each. When designing, it is necessary to confirm that the equipment power level can be covered. When the measured margin of the established link is less than 3dB, it is recommended to reduce the number of transfer points or replace it with a longer distance model. EB-LINK can assist in calculating the actual distance and provide testing and shipment one by one. Tel: 0755-83179002.
Critical problems cannot be postponed: if the temperature changes or if the connector becomes a little dirtier, the link may be completely interrupted. After completing the three steps of measuring, cleaning, and changing lines, and then talking about changing equipment, the direction will be clear.