The FOA Reference For Fiber Optics
Fiber Optic Measurement Units: "dB" and "dBm" Whenever tests are performed on fiber optic networks, the results are displayed on a power meter, OLTS or OTDR
What is a normal optical power level for an ONT module to receive
Home / What is a normal optical power level for an ONT module to receive
If either Tx or Rx is in the -30 dBm or lower range that's usually indicative of there being no actual signal received and the transceiver is reporting the "noise floor" of the receiver stage. Transmit power is typically good when it is in the 6 dB range between -1 and -7 dBm. Because optical power levels range widely, the decibel-milliwatt (dBm) is used instead of a linear unit like the milliwatt (mW). The dBm scale is logarithmic, meaning a small numerical change represents a large change in actual light power. Significant deviations or fluctuations can indicate a power supply issue within the ONT. What to look for:</p> <ul> <li><b>Normal range:</b> -8dBm to -27dBm for GPON</li> <li><b>Too hot (above. Well, I've seen situations when -30 was still ok and without errors, but it strictly depends on the particular ONT's optical receiver unit.
