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Rolling Your Own Wireless Communications System?
nuggetman asks: "My high school, like most others, has a theater program. One critical element of the show is the tech crew - the group of people behind the scenes who keep it all running. Communication between the stage manager (myself) and crew members (as well as between crew members) is critical. For this job right now, we're using standard hand-held walkie-talkies. They get the job done, but they're susceptible to dead batteries, incompatibility between VOX headsets, and interference from janitors, the office, hall monitors, and even the local McDonald's. We've been wanting to invest in a theater-communication system, but they can run extremely expensive. Is there any hardware out there that could use a standard PC (Linux or Windows) and some wireless headsets to roll your own communication system that could cover a long enough range (say the theater which is the size of a gym plus a decent range outside it) at a low enough cost? Our school just installed 802.11b/g throughout the hallways, so we could tap into that if necessary and add our own router near the stage if we had to."
... which was admittedly about 18 years ago, we were happy to have the very latest technology... microphones and headphones (well, it was on a school-sized budget :-)
To be honest, I'd be surprised if WiFi would help you very much - it'd have to be a VoIP network, which isn't an obvious use of WiFi (the range is too short - most people would simply shout!)
Bluetooth might be an option, but they're basically clever walkie-talkies. Buy some rechargeable batteries and carry them. Sometimes the "clever" solution is the low-tech one...
Simon.
Physicists get Hadrons!
I'm sure there are probably a lot of problems with interference, but shouldn't it be possible to just get better walkie-talkies? Computers have their own problems too, and I'd imagine that any device you are using to communicate will have dead battery problems (unless you want to have 20 ft cords running all over the place).
Just buy a few ClearCom headsets. If wireless costs too much for you, get the old-style models and some lengths of XLR cable. Why waste time with all this computer stuff? It just complicates things. Use the simplest solution.
Why not buy some new handheld walki-talkies that have built in encryption (digital), wouldn't that be cheaper/easier than any computer network?
No, this is just silly. A laptop is going to be far more expensive than some high-quality two-way radios from Motorola or the like. Even if you already had the laptop, there's nothing that allows you to easily tap into VOIP via independent headsets. I'm not sure why regular, quality two-way radios (at $40 for a pair with rechargeable batteries) isn't good enough for this simple application?
Everyone is deriding the topic poster, but perhaps he's going to /. high school... It would be interesting to hear someone's cost effective solution for home brewed VOIP.
Part of the hardcore faithful who believed in Apple long before it was cool again to do so
Use the money and buy more rechargeable batteries for the Walkie Talkies. Using batteries as an excuse to go VoIP, which also uses batteries, doesn't make sense.
If interference is the real issue, look into low frequency radios with a 5 watt range.
Sounds like someone wants a project.
More information for my original post.
Consider the cost of your solution vs the cost of a regular system.
CS-222 Clearcom 2 channel base station: $876
Belt pack: $238
Headset: $149
Now you'll need a headset for the base station (which is a station by its self). So say you need 1 stage left, 1 stage right, and your base station will be at FOH for sound/lighting. That takes a basic solution to $1799 without XLR cables. Buying used you could probably save even more. Remember, not every single person needs a headset. You basically need someone stage left, stage right and FOH to give messages and give cues. I was in highschool theator and I know how much everyone loves to wear the headset to sound important. I can also remember how many cues people missed because they were messing around on them.
The problems you cite are universal for portable communications systems. Batteries going dead, bad headsets etc. The key is planning and maintenance. If it is critical to the show then make darn sure the batteries are charged before the show starts and if one doesn't last the entire show then dispose of it. (Nicads and nickel-metal hydride need to be disposed of properly, Radio Shack does this for free) Keep a couple of spare radios ready to go and charge some extra batteries as well.
The better route to go is to get a license for your own radio channel and use higher end radios like police and firemen do. Schools often have a business band license for buses or maintenance that you could use on the off hours, this keeps other people off your frequency. The radios cost more but you are paying for reliability.
Don't whine that you don't have the money, get a system designed by your local radio (Motorola) dealer and then start getting the money through grants and donations. I get solicited all the time for free stuff and sometimes the dealers can hook you up with a corporation that is changing systems out and looking for a place to donate the old (but good) equipment too.
The main thing is plan ahead, and plan for things not going perfectly.
You can use FRS frequencies with FCC-approved FRS walkie talkies.
/not/ license free.
To use any GMRS-exclusive frequencies, you MUST purchase a license from the FCC and use the appropriate call sign and operating procedures.
GMRS radios are
Jim
Forget about Wifi PDAs. Since Wifi is an always-on data connection, it's inefficient with power. Battery life sucks and you can't get headsets for them. Most have headphone jacks but no microphone jacks.
Still, if you want to try it XTEN makes a SIP softphone for PocketPC. There's probably ones for Palm OS too.
Don't buy anything. Work on sharing the football team's headsets. They probably have a bigger budget than your theatre department anyways. This should work out as long as you never have a performance during a game, which you should never do anyways!!
If they don't have one, perhaps its a good time to talk about splitting the cost of one.
I would have to say that your best option would be to invest in the system
Think about it
1) The computer crashes.
2) PortabilityWill you be able to use this everywhere? You probably aren't going to take computers with you if you travel for competitions, and if you do that takes up your setup time.
3) Lag, you need real time conferencing behind the stage and can't wait even for a second of lag time if something goes wrong.
4) InterferenceMost people in the audience probably have a cell phone which operates very close to the 802.11b standard of 2.4ghz. You would quite possibly lose signal in that event, and even if just for a momment, you would have to wait till it was over, reconnect the Wifi signal, and restart the voice program.
Wouldn't it suck if suddenly the system went down? You would have no time to troubleshoot. I was in my high school theatre team and we used a system from Telex. It was awesome. Didn't matter how much noise was around you cause you could hear the voices with no problem and no lag. Just flip on the power unit and plug in. Could even connect multiple units together for cases when you didn't want cables everywhere. We never had a single instance of failure. Do yourself a favor and buy a real system.
Having worked as a professional lighting designer/director for more than a decade (after starting in high school theatre) the answer is *NOT* to involve computers.
k scable.html~content )
For fixed positions, (left wing, right wing, green room, lighting sound booths etc.) use *WIRED ANALOG HEADSETS* like those from Chaos Audio (defunct I believe but still widely used) and Clear Comm.
Buy 'em used if you must but get proper a system but do NOT involve computers. You need this system to be reliable and simple. Lives are at stake. Yes really. As a stage hand you are the first line responders to real emergencies and theatrical events have a way of attracting real emergencies (venues that serve booze even more so).
General purpose computers *SUCK* for special purpose applications and suck and blow (at the same time!) for realtime special purpose applications.
(Credit is due for the homage made to: http://www.deadtroll.com/index2.html?/video/ossuc
FRS is not restricted in purpose. 47CFR95.193 defines the use of FRS, and the only mention of "individual" is:
There is no limitation as to the purpose of this communications with another person, other than a blanket prohibition on use in connection with a violation of federal, state, or local law. Assuming the stage crew is not supporting a production which violates the law, FRS would be a low-cost solution to this specific problem.If you want more power to cover a larger area, then MURS is available -- which are the kinds of radios that Wal-mart et.al. use. It, too, is license free.
"You may use your FRS unit for business-related communications.
License documents are neither needed nor issued. You are provided authority to operate a FRS unit in places where the FCC regulates radio communications as long as you use only an unmodified FCC certified FRS unit. An FCC certified FRS unit has an identifying label placed on it by the manufacturer. There is no age or citizenship requirement."
~J
-- I'm not a pessimist, I'm a realist. It's not my fault that life sucks so much. --
Shure makes some excellent wireless products for the music end of it. I'm sure there are other products out there that would work well. You could even be really geeky and get those Nextel radio/cellphones for the crew. I've played a venue recently that the stage guys used that.
It's either on the beat or off the beat, it's that easy.
I moderate therefore I rule!
--
This is really quite silly.. Trying to fit a square peg in a round hole if you ask me. Hardware Costs (size, weight, and battery life), software implementation, bandwidth, interferance and QoS limitations would make me think twice about utilizing 802.11 for a "simple" walkie-talkie.
How about using a technology everyone already has? Like.. a CELL PHONE..
Hell Nextel even has the "Walkie Talkie" feature.
While I'm fairly sure that some variant or successor to 802.11* will be the norm for wireless phone handsets one day, I don't think now is a good time to solve that problem with it.
:v)
Soon there will be 802.11-enabled mobiles in common use and all those base stations will make an awesome ad hoc network, but until then I'd suggest PRS handsets and headsets with VOX to save power.
If anyone is interested, I've developed a concept for sharing browser caches over LANs to speed up the access of all members here.
Vik
The technical director at my college just switched us from a 15 year old clear com system starting to show its age to a set of Motorola talkabouts. All of us hate them and use the clear coms when he is not around since we prefer them for the headsets and the fact that we don't have to worry about batteries . Full duplex is also a great feature except when everyone is trying to shout each other down.
Being a geek is a good thing. But it doesn't mean that you have to make things more complicated than they need to be.
You obviously need voice communication without (expensive) signalling. So analog voice will do just fine. Forget computer or networking based ideas, going there is only going to sidetrack you from your goal. Remember that this is about getting your theater group to communicate, not about playing with geek toys.
Someone here has already mentioned 49 MHz headsets. Radio Shack and Maxon are common brands and those should work great for you. But if you need something with a little less interference then......
FRS, or Family Radio Service is another option. The radios are fairly inexpensive and can be had for $30 each or so. They offer multiple channels and CTCSS tones (if you don't know what that means either RTFM or get back to me, it's worth your time to understand it). Those should give you the range you're looking for. You won't get interference from businesses there, that frequency band is for non-commercial use. And if you do find someone interfering then gather information and turn them in to the FCC and your interference problem is gone.
Beyond that you could go for commercial land mobile gear. It works like FRS but you have to license a channel. You do get a lot more power and range. The drawback is that the school will have to apply for a license and that takes time. You'll have to budget $300 on up for each radio with the accessories you'll want.
If it were me I would try FRS first, a trial run with a couple of borrowed radios.
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