We’re having an argument regarding the bandwidth of single mode fibre and how many cameras it’s possible to push down one fibre, for what distance, without repeating the signal.

A: Any single mode fibre has bandwidth limitations imposed by the transmission material and waveguide dispersions – these combine to give zero dispersion at 1300nm with a core diameter of 9-10um. Around 1300nm, the dispersion rate is <3.5PS/nm/km. Even with single mode fibres, bandwidth measures in the hundreds of GHz. Essentially this means it’s possible to shift video across fibre links of up to 100km at data rates of 2.5Gbps without repeaters.

How you fill that data stream is going to be up to you. You’re looking at one-and-a-half times Gigabit Ethernet rate and that’s a lot of room to move. If you were using H.265 to deliver a bitrate say 768kb/s per camera at 1080p (think Vivotek or Axis with ZipStream), that could allow for more than 2500 cameras on one fibre.

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