make a long range remote radio transimtter and receivers

[dsesmg]

Hi, I need to make a long range remote radio transimtter and receivers.
The distance is 500m and the location is in a building.
I must notice 5 people simultaneously when I push some button on a transmitter. So, five people are carrying the receivers and they will notice beeping sound from the receiver when the transmitter activates.
I thought the radio signal is the only solution to acheive it activated for this long range and in a complex location like a building. Could you please help me how to acheive this? All I need to have is just the functionality to notice multiple people simultaneously by pressing a button of some device.
Please help~!

[Soeren]

Hi,

The distance is 500m and the location is in a building.
I must notice 5 people simultaneously when I push some button on a transmitter. So, five people are carrying the receivers and they will notice beeping sound from the receiver when the transmitter activates.

Sound like you need 6 cheap PMRs (UHF band Walkie Talkies), which will have the added bonus of voice communication, but can be used with just the call feature if needs be.
You probably won't be able to make what you want any cheaper and with PMRs, standby power is low and range is more than what you need.

[dsesmg]

Hi, how are you?
That sounds very good.
Is it something like this?
http://www.dhgate.com/motorola-t4508-uhf-band-walkie-talkie-two/p-ff808081228ca96701228d6c0c080dc7.html
I don't quite need the voice communication.
Is there any way I could build my own transmitter and receiver using something like Bluetooth?
I need it very very compact and small so that no one could ever notice that I am carrying it.

[Soeren]

Hi,


They could be found much cheaper.
Like here: http://www.dealextreme.com/search.dx/search.walkie%20talkie

[dsesmg]

thank you
i will look for those.

[dsesmg]

Can someone build a customized transmitter and receiver?
The communication functionality doesn't necessary for me.
Only the LED flash and piezo sound is enough.
The distance is 500m range and the it must be operated in a complex building where there are many offices.
I want to simply buy a customized one.
Please, if someone able to do this, contact me.

[amrosik]

i have a similar problem, i only want to send 2-d position datas from my computer to robot and a feedback data of the current position. is it possible to build that yourself or to modify these walkie talkies?

[Soeren]

Hi,

i have a similar problem, i only want to send 2-d position datas from my computer to robot and a feedback data of the current position. is it possible to build that yourself or to modify these walkie talkies?

There are telemetri modules (transceivers working in the ISM bands) that are as good as plug 'n' play if you can make do with less range.

[amrosik]

ok thank you, can i build them low priced, do you know any internet sources where i can find them?

if you can make do with less range.

50m are enough.

[amrosik]

oh, i dont think that this is the right. in ONLY need position data, nothing more, that takes maybe 2 bytes, whatever.

perhaps i need 4bytes per second or something. i think a radiomodul is better, but not a bought one because they perform more than i need.

[chelmi]

oh, i dont think that this is the right. in ONLY need position data, nothing more, that takes maybe 2 bytes, whatever.

perhaps i need 4bytes per second or something. i think a radiomodul is better, but not a bought one because they perform more than i need.

Building one yourself will cost you more and debugging it will give you headaches (especially if you don't know what you're doing and don't have the proper equipment)
Who cares if they perform more? unless you have a really tight battery budget...

http://www.sparkfun.com/commerce/categories.php?c=79

[Soeren]

Hi,

oh, i dont think that this is the right. in ONLY need position data, nothing more, that takes maybe 2 bytes, whatever.

perhaps i need 4bytes per second or something. i think a radiomodul is better, but not a bought one because they perform more than i need.

It's like saying that you only need 1MB RAM extra for your PC, so you won't get anything larger!
I think the lowest rate the TX/RX-modules come in, is around 1kb/s or so.

They ARE radiomodules, I just used the term telemetry since that's what you want to do with them.
If you wanna do it really cheap, hack a wireless doorbell or similar.
If you don't wanna buy anything at all... I wish you the best of luck - and you're gonna need it, because building HF modules does take a wee bit of knowledge and experience.

[amrosik]

yes you are right.
i always have a bad conscience if i use something and i dont know how it is built up.
isnt it sufficient to place two simple resonant circuits, one of them to my computer? what else is required to build such radio modules, what else is in this things beside a lc-circuit?