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I am working on a project where I am going to need long distance communication and I am unsure the best way to go about it. I am mainly trying to decide between fiber optic or Ethernet and decide some of the pros and cons of each.

I would be working on a distance of somewhere between 100m-300m. I'm looking to transmit relatively simple controls signals to a remote test setup and have it respond with live data and video from multiple cameras and sensor sources. The control setup and test setup would be custom built by myself so I am free to pick any communication protocol/setup I desire. Oh and the system will be outside so durability is somewhat of a factor.

Does anyone have recommendations for long distance communication? I'm leaning towards fiber because I was under the impression that Ethernet connections begin to breakdown over 100m but I have seen a few posts here that point otherwise. I'm also a bit new to communication protocols and connections so any direction or advice on what is wise to use for long distance connections would be helpful.

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    \$\begingroup\$ Wiki says " The segment length for a 100BASE-T cable is limited to 100 metres (328 ft) (as with 10BASE-T and gigabit Ethernet)." This limit is, AFAICR, fundamental due to the collision detection mechanism. \$\endgroup\$ – The Photon Oct 28 '16 at 19:11
  • \$\begingroup\$ @ThePhoton That's what I read as well which is why I had ruled out Ethernet initially but I wasn't sure if that was just the speed begins to break down or the integrity of your signal/data begins to degrade. \$\endgroup\$ – Wired365 Oct 28 '16 at 19:14
  • \$\begingroup\$ @Wired365 what would be the frequency of the signals you want to send? and what signal levels (in volts) are you looking at and how many signals do you want to send? \$\endgroup\$ – Miguel Sanchez Oct 28 '16 at 19:20
  • \$\begingroup\$ See electronics.stackexchange.com/questions/156031/… \$\endgroup\$ – pjc50 Oct 28 '16 at 19:25
  • \$\begingroup\$ @MiguelSanchez The design is still in flux a bit but we are probably looking at a live feed from about 3-4 HD (1080p) cameras along with data transmission of various sensor values at a rate of 1kHz+. The MCU I was looking at use 3.3V on their board but it would be simple to add some extra circuitry to step those levels up or down as desired, so the I didn't really have voltage requirements, I figured that would be driven by the communication protocol. \$\endgroup\$ – Wired365 Oct 28 '16 at 19:42
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100 meters is the standard limit for Ethernet connections, though many people have success beyond that (dependent on timing, shielding, conductor quality, RF environment, transceiver signal strength, and a variety of other factors). If you're planning on several video streams or are closer to 300m than 100m, fiber makes the most sense (if you run OM3 or OM4 you have the option of starting with inexpensive 1000BASE-SX multi-mode and upgrading to 10GBASE-SR if/when you require the additional bandwidth; OM3 will give you 300m with 10GBASE-SR). You can connect the fiber to a switch on the remote side and then run copper a short distance to the cameras and sensors (this also gives you the option of using PoE).

Make sure you use burial-grade cable in either case.

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  • \$\begingroup\$ Thanks Scott! That helps. With regard to the connection should I keep a dedicated separate line for the video streams and keep my data bus on another or do you think I would be fine using a single cable? Or is that not really worth debating over and it's easy to just run more than one fiber? \$\endgroup\$ – Wired365 Oct 28 '16 at 19:46
  • \$\begingroup\$ Cost is the consideration - do the bandwidth maths and see. Probably the data bus is much less than the video. \$\endgroup\$ – pjc50 Oct 28 '16 at 20:07
  • \$\begingroup\$ @pjc50 This may be a dumb concern, but I was more worried about clobbering the control data with the video data if I were to use the same cable. \$\endgroup\$ – Wired365 Oct 31 '16 at 13:14
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    \$\begingroup\$ It's a reasonable concern, but a video stream should be under 100Mbit and in most cases will be under 10Mbit. Gigabit systems are full-duplex, so traffic in one direction does not interfere with traffic in the other. You could even reserve bandwidth for different streams using some of the fancier managed switches. Or you could just run two cables/fibers. \$\endgroup\$ – pjc50 Oct 31 '16 at 13:26
  • \$\begingroup\$ @pjc50 Oh okay that's good to know. Thinking about my design a little bit more this morning and rereading Scott's answer I realized that I can just run a single fiber as the long distance connection between two switches and connect everything on the test setup with a local copper network. Thanks for all of your help! \$\endgroup\$ – Wired365 Oct 31 '16 at 13:54
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Have you looked at ...

GigE Vision

GigE Vision is an interface standard introduced in 2006 for high-performance industrial cameras. It provides a framework for transmitting high-speed video and related control data over Ethernet networks.

GigE Vision can transmit over ethernet and max distance that this page says is around 100 meters, but I'm not too sure about that as other pages give more conservative figures of 75 meters or less.

Again this required dedicated lines between camera and the destination I'm not sure that multiple cameras can share the same link.

Then there is also

Camera Link

Camera Link is a serial communication protocol standard[1] designed for computer vision applications based on the National Semiconductor interface Channel-link.

But distance is severely limited to around 10 meters just added for completeness..

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