Hi, I need to make some type of 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~!
Linx has some long range transmitters/receivers (http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=RXM-315-LR-ND)
That's the easy part - the antenna setup is going to be critical to actually get that far in a building with any reliability.
They have a good section on antenna use in the datasheet PDF available from that page.