Transporting Video Signal Over Optical Fiber

[JohnMoore1000]

Hello Everyone,


I have stumbled upon an issue while doing an application. In this application there is an existing multimode fiber which is installed. We will be using Sony PXW-Z90 and QuestTel's optical extenders. My application exceeds a one kilometer distance which is not supported by multimode fiber. Since changing multimode to singlemode fiber is not an option, I would like to know if there is an option that exists that doesn't require me to change the existing infrastructure to boost the optical signal.


I am truly looking forward to a good response,
John

[Cornucopia]

"Not supported" doesn't necessarily mean "won't work", it means you are at higher risk of it not working. There are other factors, and your exact case MAY be such that you can get away with ussing multi-mode beyond the recommendation. But it is a risk.

The alternative is to have an intermediary to refresh the signal(s), such as a switcher or DA, on a hop/hops between legs.


Scott

[JohnMoore1000]

Thank you for your response. As it happens, the issue becomes apparent when it is connected to monitors.The video signal becomes week and pixelated. We are trying to lower the resolution however application requires full 3G at end.

[pandy]

You need to search for SDI to fiber with higher optical output power (in your case like +10..12dBm) and better sensitivity (literally long range solution)... there is no easy answer - there are some optical amplifiers or optical power doublers but this is more laboratory or space military equipment not general easily available product - single mode FO are used not accidentally for long range.

[Sharc]

Higher transmit power and/or higher receiver sensitivity does not really help in this case. The reach (max. fibre length) is dipersion limited (bandwidth of the multimode fibre, modal dispersion, ps/nm/km) rather than attenuation limited (dB).
Why is single mode fibre not an option? It would solve all problems and is by far the best option. Boosters and intermediate amplifiers etc. is just tinkering IMO and more expensive than a new singlemode fibrecable.

[JohnMoore1000]

Thank you for detailed responses. Currently, I only have multimode optical fiber in the infrastructure. If you have any further feedback, please inform me.

[pandy]

Higher transmit power and/or higher receiver sensitivity does not really help in this case. The reach (max. fibre length) is dipersion limited (bandwidth of the multimode fibre, modal dispersion, ps/nm/km) rather than attenuation limited (dB).
Why is single mode fibre not an option? It would solve all problems and is by far the best option. Boosters and intermediate amplifiers etc. is just tinkering IMO and more expensive than a new singlemode fibrecable.

True but impact of the modal dispersion can be reduced if coherent transmitter and shorter wavelength is used - 3Gbps at 1km should be feasible - depends on FO type (OM3 or higher).

[Sharc]

Higher transmit power and/or higher receiver sensitivity does not really help in this case. The reach (max. fibre length) is dipersion limited (bandwidth of the multimode fibre, modal dispersion, ps/nm/km) rather than attenuation limited (dB).
Why is single mode fibre not an option? It would solve all problems and is by far the best option. Boosters and intermediate amplifiers etc. is just tinkering IMO and more expensive than a new singlemode fibrecable.

True but impact of the modal dispersion can be reduced if coherent transmitter and shorter wavelength is used - 3Gbps at 1km should be feasible - depends on FO type (OM3 or higher).

Coherent source does not really help either. It would only reduce the chromatic dispersion, but the limiting factor here is modal dispersion caused by the multimode fibre rather than chromatic dispersion of the many modes. Modal dispersion is due to the different propagation delays of the individual modes of multimode fibres. Maybe a higher quality graded index multimode fibre for ~1300nm wavelenght (the wavelength of the OP's system) could help as the missing gap seems to be marginal here. Also, checking and carefully cleaning the connectors may help.
Better use single mode fibres and the problem is solved.