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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."
1) Set up a private Counter Strike Server somewhere on the school LAN.
2) Get a laptop (with an 802.11g card in it, of course) and backpack for each crewmember.
3) Every crew member joins the game on their laptop, sets the laptop to never suspend, throws it in their backpack, and uses headsets to communicate with their team members!
Other than the sound of an explosion every three minutes or so, and the occasional "Terrorists Win!" all your communications problems are solved!
libertarianswag.com
Use yelling. Everyone comes equiped with all the right hardware. No sweat.
... 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!
Some of my friends and I make up the A/V crew at my school, and I came up with an ingenious solution yet to be implemented: a zipline. The A/V booth is about 20 feet higher than the stage and a good 75 feet away, and we decided that a zipline would be the best way to get down to the stage to tell somebody something important.
I guess if you need to tell somebody something who's level with you then you'd have to invest in some model rocket engines or something.
The Human Cow - bringing you scrumtrelescence since 1995
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).
Makes you wonder how in the hell Shakespear ever got by without a Slashdot subscription.
Sheesh. It's high school, dude.
"If you want to improve, be content to be thought foolish and stupid." - Epictetus
Sorry, wrong company. I meant Vocera.
http://www.vocera.com
Sounds like a battery-management issue more than something requiring a complex software solution.
Linux: Free if your time is worthless.
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?
All you need is some tin cans and some stri-
Wait, does string count as "wireless?"
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?
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.
Your best bet for cost and effectiveness is to get nicer walkie-talkies. At $40/pair Motorola FRS/GMRS radios have 22 channels, and a 2-mile range, plus you can get headset/microphones to go with em. I own a couple pairs and they're durable as hell (you shouldn't drop them in a lake, but mine came back to life anyway) and have 12+ continuous hrs on a couple AAs. Plus now you can multichannel your crew - Ch 1 is Lights/sound Ch 2 is backstage crew.... ~J >-- I'm not a pessimist, I'm a realist. It's not my fault that life sucks so much. --
-- I'm not a pessimist, I'm a realist. It's not my fault that life sucks so much. --
I work with a lot of presentations and lectures and I'm dying to know if there is any consumer or prosumer level digital microphone systems out there? Everything that you can find both at cheap ass Radio Shack and even high end audio stores is varying degrees of wireless. 900Mhz or 2.4Ghz just like cordless phones. Some through the word "digital" around but are still susceptible to interference and static.
What I'm dreaming of is something that is purely digital, from the device the speaker wears all the way to the speaker. I envision something like a Bluetooth wireless microphone similar to the bluetooth headsets that some cellular phones use. This bluetooth microphone would relay to either a box in the speaker's pocket or inside the lecturn. This box would then use CAT-5 or 802.11 to transmit the stream as a WAV or MP3 so that it could be played on a SlimMP3 or Shuttle connected directly to the speaker system. In theory the speaker could roam freely and speak clearly and sound crystal clear.
Is there anythign like this? One place that I work for is about 100 feet from high power lines. The resulting RF interference renders even the most expensive $600-800 wireless microphone solutions worthless. Wired microphone even have a problem, even with grounding wires you still pick up pops clicks and hums over fifty feet.
So, how about it? There are plenty of devices that can take an audio stream off a network and output a sound wave? How about a device that can record the sound wave and output an audio stream?
FYI - consumer or prosumer means less than four digits...I'm sure studios and recording studios have plenty of expensive options available.
-JoeShmoe
.
-- I wonder which will go down in history as the bigger failure: the War on Drugs or the War on Filesharing
You're a high school kid with walkie-talkies that can be used in pranks on McDonalds customers, janitors, and hall monitors, and you want to get rid of them?
The U.S. education system must be going downhill fast.
For something this "critical", you need technology that won't fail, but will also work in the kind of vast distances you're talking about. I suggest tin cans and string. Of course, you'll have to make sure nobody in the audience brought scissors, but with all the hi-tech anit-terrorism stuff they throw in schools these days, surely nobody can get in with sharp objects.
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.
Basically, it mimics a standard phone line, and any telephone device you plug in can communicate with the others. You can run long cables and use splitters [nearly] to your heart's content. For about $30-$50 per station (hundreds less than a real, however superior, Clear-Com system), you can purchase corded or cordless headset telephones which work nearly as well.
If you do that, be sure to get phones with mute capability; and if you go cordless, be sure to check on battery life and try to get phones that don't beep too loudly. You might even need to disassemble the cordless phone and disable the internal beeper to make it silent.
Two things that are really nice about true Clear-Com systems is that (1) they can be operated silently (i.e., without beeping), and (2) their mute/talk controls can be operated by feel alone -- you don't need to look at a mute LED to determine whether or not you're muted. Those features are hard to come by on unmodified corded and cordless phones.
In general, a theater intercom system needs to be absolutely reliable, and should also be full-duplex (which walkie-talkies are not, but telephones are). I'd shy away from creating a custom wireless soultion with unproven technology -- it will take much more time to develop and won't be as reliable. If anything goes wrong during a show, or if reception isn't good enough, you've got big trouble.
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.
Gaaah!!! No, no, no!!! 5 watt transmitters in a backstage environment?!? I recently had to completely ban our Motorola 2-watt radios from the booths in both of our theatres, because when someone tried to talk on them, it would often induce RFI into the sound equipment, headset system, and, worst of all, the light board. You key up one of those things next to an unbalanced signal line, and *everyone*'s gonna know it. :)
In a theatre, nearly everything is temporary - speakers need to be in this spot for this show, then, six weeks later, completely across the room - hence, most cabling and playback/processing equipment is portable, and certainly not run in nice steel conduit - which, sadly, leaves it susceptible to RFI.
Yes, I've also banned the use of cell phones.
(Master Electrician, Arden Theatre Company, Philadelphia, PA.)
If all the world's a stage, anyone who says they want better lighting spends far too much time in a dark theatre.
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.
First off, let me preface this by saying that i have worked building large-scale theater shows, and as a lighting designer for 7 years. I have worked on shows including the Lion King, Cher, Phanton of the Opera, Miss Saigon, Tim McGraw, the Pan American Games, as well as numerous regional and touring theater shows and outdoor festivals.
Quite literally the only thing these shows have in common is the need for clear, reliable crew communications. During setup/strike (installation/teardown), crews usually have portable radios (Motorola Walkie-talkies generally), so everyone can keep in touch without shouting or running around looking for each other. Essential for big shows, unnecessary but nice for small one. However, for all shows, only "Clearcom" communications are used.
Clearcom is a brand-name of wired "party-line" communications sets. It's used generically for other brand systems, like Telex, HME, etc. It's the same thing you see camera operators on TV shoots wearing. Everyone has a headset and beltpac, and can talk to one another on a common "channel". Everything is hard-wired, and everything works, all the time, every time. The systems is used for calling show cues, as well as any other necessary communication during showtime.
However, the "wired" issue becomes a problem for some people. While audio and lighting techs can often stay put (they sit behind a board), stagehand/stage managers have to be mobile, often on stage. Usually they need to be able to communicate in a high-noise environment, and it must work reliably.
The only way to do this is via a wireless clearcom system. Telex, HME, and Clearcom are the big three, and all of their systems are inter-operable. I personally like HME's RadioComm, but all systems have their own benefits. Simply put, these systems are expensive but necessary. For a school situation, you can probably get away with 2 wireless stations, and 4 wired. But you can't cheap out on this. You need great headsets, and equally good beltpacs to go with them. When you're midshow, and you can't hear your cue, you'll know why.
I hope this helps. I realize that you were looking for a cheap way around the problem, but there isn't one. You'll find that with 95% of things in theater, cheaping-out never works. You buy a crappy light, or sound equipment, or cleacom, and life sux but things go on. You cheap out on rigging or construction, and people die. It's as simple as that.
-Michael Roy
-Michael Roy Some people are like Slinkies. Not really useful, but you can't help smiling when you see one tumble down