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What do you think about FSO(Free Space Optical)?

wendydu

     As Freee Space Optical has been talked several years, what do you think about it? In the future, will this technology develop a lot or just be a concept? It combine the radio and the fibre opticle communication, but does it have any new advantages beside these two maturer technology?

     Maybe you kown some projects or products about this technology, please don't hesitate to tell us.

  • Did a search on google and it said that FSO originally developed by millitary and NASA and has been used for more than three decades in various forms to provide fast communication links in remote locations.

    I think this technology will develop. Saw some advantages found on website like requires no RF spectrum licensing, is immune to RF Interference examples.... Hopefully it will have a higher range of speed compared to RF technology in future.

  • Don't forget that there are problems with FSO links.

    FSO do offer license free high capacity links but their range is limited.

     

    They are affected by atmospheric particles (dust, smoke and fog) as well as heat shimmer and being blinded by the Sun.                                     Although manufacturers claim some quite long path lengths (6km or more) you have to take into account the atmospheric conditions of your area.    

     

    If you need telecoms grade service (99.99% availability) then my own tests in the UK limited such links to 1km or under. Positioning is also important as you need to avoid allowing the equipment the view of the rising or setting sun as this will "blind" the unit and stop the link.                                                                                                                                                                                                                      

     

    Also due to their narrow beam width they must be held steady, so solid mounting bracketry must be used especially in wind positions. You also need to avoid firing the link across a flat roof as summer heat shimmer will distort the transmitted/received signal.

     

     

    As you can tell they are not quite as easy to use as it appears and why they sometimes have a bad press as "unreliable". They're not but are frequently badly designed and installed.

     

    There are 3 main types in commercial use:

     

    Passive: They have no electronics. They use lenses to focus a terminated fibre optic cable. Range >100m (70~80m more common)

     

    Single source: They use a single diode for transmission. Range >500m

     

    Multiple source: (typically Quad) They use multiple diodes for transmission. Range >1500m (typically 1000m for a reliable link)

  • in reply to e14 Contributor

    Koh and Chris Halicki, Thank you very much.

    Chris, as you said there are 3 main types in commercial use including passive, single source and multiple source, each type has its own range limit. But do you kown what application do these type apply? And what's the different equipment or device these types will use?

    Besides, does anybody kown any manufacturer produing this kind of device or equipment?

  • in reply to wendydu

    They have a few uses but mainly as Data Comms links. The good side to FSO is that you can have bandwidth's of 1Gbit or 10Gbit so are sometimes used as a backup link for an underground fibre.

     

    They are sometimes used in a single direction for CCTV backhaul.

     

    There are quite a few manufacturer's about. Have a look at www.mrv.com www.pavdata.com