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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."
Sounds like a battery-management issue more than something requiring a complex software solution.
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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
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FRS radios would be illegal. They are regualted and are only allowed to be used for individual purposes. If the FCC catches your school using them you can end up with a hefty fine, and don't think the FCC won't I know several schools that it's happened to.
Use cordless phones. My mother is a theater teacher and my dad runs tech. We use a pbx like unit that lets us connect many phones together and we use a mixture of corded and cordless phones to get the job done. It dosn't get much more inexpensive. Ohh and my advice... the computer stuff always gets banged up when other people use it.. so try to stay away from anything that breaks easy.
You could have a GMRS repeater you are unaware of, it would significantly improve range. But I have never seen a Target or WalMart use GMRS at all, typically they have "industrial" radio licenses.
Exactly. I played a show recently where the crew had these. Seemed to work really well.
It's either on the beat or off the beat, it's that easy.
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I'm assuming that you people in the USA dont have a band allocated to the FRS?
Here in Canada, we have something called (you guessed it) FRS. Stands for Family Radio Service. The handsets run for around 25-40 bux canadian. You can usually get them in a pair for 50 dollars. They put out a half watt on vhf(get about a mile of range), and operate in a band allocated ONLY to the frs. There are..14 channels?
Hm, some quick googling turns up the fact that you DO have frs down there. Other than intermod, there isnt really much interference on the band. If you are using normal walkie-talkies, try some FRS radios. If the channel you are on has interference..switch to one of the others.
Here is the bandplan from the fcc.
Here are the radios at Best buy.
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In my high school theatre we have a clear-com system that we use for general communication but there are times on our larger productions in which it simply will not do. To remedy this, a friend and I hacked together a system by which to patch our clear-com output into our assisted listening devices. After completing this, we could give our stage crew boxes which would allow them to hear anything that went on on headset. We have two wireless microphones (1 lav, 1 handheld) which we gave to important crew members and patched their output back into the clear-com system. This allowed them to have two-way wireless communication using our existing equipment. Aside from that, I have had mixed luck with FRS depending on the space (all used on small productions). Another idea, if you are wanting to have use computers for this solution would be to install terminals on the sides of the stage which would run a custom software solution that would display cue information upon receiving commands from the stage manager. (I almost built this last year.) Also, a simple IRC system would work as well if you wanted text-based messaging but other than that, I think that a dedicated communications system would do you good.
Get your school on a multiline phone plan with low minutes but unlimited push to talk...long distance walkie talkie that no one can look in on and you won't pick up anyone else's stuff...maybe you could do 4 phones for around $100 a month? That still might be too much, but with free or discounted equipment the initial cost shouldn't be too much, maybe around $600, with a monthly fee. Sprint, Verizon, and Nextel all offer unlimited PTT...(that is if phones would even work in your theatre)