Influence of ONU weak light on network speed

ONU is what we commonly call “light cat”, ONU low light refers to the phenomenon that the optical power received by the ONU is less than the receiving sensitivity of the ONU. The receiving sensitivity of the ONU refers to the minimum optical power that the ONU can receive during normal operation. Usually, the receiving sensitivity index of the home broadband ONU is -27dBm; therefore, the ONU receiving optical power lower than -27dBm is generally defined as the ONU weak light.

ONU is what we commonly call “light cat”, ONU low light refers to the phenomenon that the optical power received by the ONU is less than the receiving sensitivity of the ONU. The receiving sensitivity of the ONU refers to the minimum optical power that the ONU can receive during normal operation. Usually, the receiving sensitivity index of the home broadband ONU is -27dBm; therefore, the ONU receiving optical power lower than -27dBm is generally defined as the ONU weak light.

There are many factors that affect the user’s online experience. The ONU’s low light mainly affects the network speed. In order to test the impact of ONU weak light on the user’s network speed, Laodingtou built the following test model.

Connect an adjustable attenuator and a PON optical power meter in series between the leather cable and the ONU, so that the PON optical power meter can be used to measure the received optical power of the ONU (the downstream optical power of the test). The difference between the received optical power of the ONU is about 0.3dB (1 fiber jumper minus the attenuation of an active connection). The actual test site is like this.

By adjusting the attenuation of the adjustable attenuator, the attenuation of the ODN link can be increased, and the received optical power of the ONU can be changed. The change of network speed is tested by connecting the laptop to the ONU with a network cable. This method is used to test the 300M broadband of Laodingtoujia, and the test results are as follows.

The actual receiving sensitivity of most ONUs is better than the index by about 1.0dB. For example, the ONUs in this test can still work normally when the receiving optical power is higher than -27.98dBm. When the received optical power is lower than -27.98dBm, the downlink network speed drops rapidly with the decrease of the received optical power, and maintains a very low network speed within a certain optical power range until the network is completely interrupted.