Please do keep in mind that I have no background in electronic communication. The idea is to receive data from electronics at long distances.
The distance I will be looking at to read data from electronics is around 10 km (6 miles) and possibly at a later stage longer distances and I would like to keep cost as low as possible.
The route that seems to be low cost is getting a raspberry pi zero, connect the electronic device to it and then transmit the data received from the device over radio.
The user will have a app on his or her phone/device which will receive these radio signals and then decode it into an app which the user in return can understand.
The problem, if I am not mistaken, with this route is security won't be that great as anybody with the same frequency will be able to receive the data and also, again if not mistaken, it is illegal the transmit radio signals over great distances.
The questions I have is
- Is this theory even possible ?
- Is there a better way of achieving this goal ?
- What topics do I have to research to understand how electronic devices can communicate with a pie as well as sending and receiving radio signals and decoding it ?
A simple example is that if a switch is flipped on or off the pi is notified the signal is broadcasted the user's phone receives it and then the user is notified through his or her phone.
EDITED I see a lot of people mention GSM but this uses a cellular network, sadly this option won't suffice as there is no cellular network in the area the pi will be used.