23 Feb Why 120km Gigabit SFP has lower TX power as 80km SFP?

Question: Many customers have asked why 120km Gigabit SFP has the same or even lower transmit power as compared to 80km SFP? Shouldn’t it be vice versa?

Answer: The explanation is simple. 120km modules extend the range thanks to receiver not transmitter. 120km modules have much better receiving sensitivity than 80km modules. If we look at product specification than we can see that 80 km module has Max Tx: 5 dBm, Min Rx: -24 dBm. And 120km module: Max Tx: 5 dBm, Min Rx: -32 dBm. So we can see that receiver is more precise with bigger sensitivity in 120km module – which gives more working distance.