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Ethernet Intercom Systems?
Milo_Mindbender asks: "Has anyone seen an intercom system that operates entirely over Ethernet? Ideally, I'm looking for something like they use in TV and theatre, a self-contained belt-pack you plug a headset in one side and an ethernet cable (or wireless card) in the other. It needs to be controlable by a master computer that can link each user to any number of channels and change them around on the fly. A channel should be full-duplex and allow multiple people to talk/listen at once like a telephone conference call. This is for an entertainment venue where guests will use the system as a 'radio simulator' while playing multiplayer games and the staff will use it to help manage the facility. I'd prefer a ready-made system, but if you have suggestions for hardware/software that could be converted into such a system I won't complain!" While something like this would be a fun thin to do, why would someone use ethernet when radio-based (or, if you are careful...wire-based) communication products are cheaper and more robust?
Several people now have dragged IP into this... The guy isn't asking for a TCP/IP intercom, he's asking for an Ethernet intercom. There is a difference.
I'm assuming that they are already putting the Ethernet infrastructure in place, and figure that if they can use that for what they are doing then why put a second (or third or...) infrastructure in place.
Most places are already using CAT5 throughout and running multiple points for the computer network and the phone system and... I've been in places like that (I still am) and just because it's Cat5 doesn't mean it's running IP.
I don't have a solution using Ethernet, but a quick google search showed one or two possibilities...
-- Under/Overrated is meta-moderation, and therefore is Redundant.
why would someone use ethernet when radio-based (or, if you are careful...wire-based) communication products are cheaper and more robust?
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It needs to be controlable by a master computer that can link each user to any number of channels and change them around on the fly.
isn't so easy to do with plain old radio..
cool application, but likely VERY expensive..
Well - you're not gonna like the answer, but here it is. As clark625 has stated, ??-over-IP is NOT always the solution - and here is a perfect example. But what you want can be done with dedicated boxes.
Clearcom makes wildly popular icom boxes. They have mainstations of all shapes and sizes - the more popular ones with either two or four isolated channels that can be "party-lined" together. The connector is XLR (3-wire mic cable), and each channel can support quite a few beltpacks at the same time. I also hear tell that they make wireless units, but I have no experience with these.
Now - if you've got big bucks, you can get exactly what you want - an RTS Zeus DSP Intercom matrix. It is computer controlled, and allows for an unbelievable amount of private channels, grouping, external audio sources, etc etc etc. You can either get dumb stations (where their listen and talk sources and destinations are constant and pre-programmed), or you can buy the intelligent stations that have 12 programmable sources/destinations (not to mention you can have multiple pages and many other things). Each destination can be a party line, a private tunnel with an individual station, or an external source (like radio in our config). The stations are all 9-pin connections, and I can't tell you how wonderful this system is, if you have the money. They also make VERY reliable full duplex wireless units that I use daily.
So those are the best bets for your situation - in this case, there's NO reason to reinvent the wheel. Use boxes that were MEANT to do the job properly, and don't overcomplicate things. Besides - I'm sure that in the middle of a production, the last thing you want is a script kiddie 0wn1ng your intercom system. Remember - there's no such thing as rm -rf / in the world of professional intercoms.
Theres 2 intercom lines free for you.
Using that extra pair can cause a serious drop in the performance of your Ethernet- the twisted pair/differential driver set up is pretty good at eliminating noise induced by outside sources, but only if the source of the noise is at a distance >> the spacing of the pairs. Since all 4 pairs are in the same shield, running intercom on the unused 2 pairs can interfere with the data (and vice versa). Also- you have to watch out since most Ethernet cards terminate the unused pairs into a direct short or into a 75 ohm resistor. Depending on how often you use it, it may still be acceptable, but you need to be aware that it can affect things.
Also, using the extra pairs will prevent you from running copper-gigabit ethernet, which uses all 4 pairs.