x-posted to /r/Optics
So here's something a little different for you. The TLDR is: I'm looking to do seamless re-patching of a live fiber connection, possibly with multiplexers or ??? device.
The story: I work for a very large theater. For one of our shows, we have an orchestra that plays on a moveable set piece. It's a full-sized orchestra and takes up about 100 channels of audio (50 coming from the instruments, 50 going to the in-ear monitors). This orchestra set piece can move around the entire stage and can also go below the stage. Depending on the location of the set piece (aka, "Orchestra Car"), the audio and power is plugged into one of four different cables. These cables are swapped live, while the orchestra is playing, via a make-before-break action (plug in the second cable before you unplug the first cable). This can be done because the audio is currently over very large analog cables. This all happens in less than 10 seconds. We're looking to go digital, for various reasons.
This picture hopefully explains most of what I'm looking for. First, I need to send an identical fiber signal to 4 different points on stage. When a cable needs to be swapped, the waiting cable is plugged in, an A/B switch is toggled, the previous cable is unplugged, and the receiving network switch (or other possible optical devices) theoretically never sees a change in the incoming signal beyond maybe a couple corrupted/dropped packets.
The sending part I think I have down, except for two questions:
- Does a multiplexer distribute an incoming fiber to all outgoing ports, essentially acting as a splitter? In my mind, either each output of the multiplexer sees all signals and it's up to the end device to figure out with frequency it needs, OR each output port is manually configured for the proper frequency, but looking at multiplexors online I'm missing how that's done.
- If I use a simple cheap passive splitter, such as this unit (https://www.markertek.com/product/cmx-mm1x3lc-001/camplex-cmx-mm1x3lc-001-om3-50u-multimode-lc-fiber-optic-1x3-splitter-cable-1-foot) do I need to worry about signal loss? We're talking distances of low hundreds of feet, not thousands.
The receiving part is where I'm stumbling more. I need to merge the signal from any of four possible cables into the one cable that goes into the receiving device. To be clear, only one cable will ever be active at a time (I'm assuming bad things would happen if two near-identical signals came in simultaneously). I'm looking for a "combiner", and I'm not sure a multiplexer/deplexer works the way I'm hoping.
To preemptively address some possible comments:
- I've already investigated the various ethernet-based redundancy options available for running multiple cables (spanning tree, ERPS, etc). In a nutshell, they can work great when losing a connection, but they take too long to establish a new connection and in general get too unhappy when there's a sequence of up/down connections. Though if anyone knows of less-common protocols to explore, I'm open.
- I'm not worried about hardware or cable failure - whatever solution I find will be replicated with an identical second setup. The handling of those identical datastreams are handled elsewhere.
- Coax is another possibility I'm exploring.
Thoughts?
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