Hello everyone i am new to raspberry pi and apologize if its funny..i have seen projects using raspberry pi as FM transmitter..and i am wondering if i can make mobile phones from raspberry pi that can have voice communication and video communication without the mobile towers(obviously the range matters with antenna size)..it will be like peer to peer communication and own encryption schemes that will avoid censorship. is this feasible or has some disadvantages??
It can be done, using wifidongles.
Set them up in ad-hoc mode and transfer the data. You probably need 2 (webcams with) microphones that connects to the USBport which works on the RPi as well, so a sufficient powersupply to go with those. 'Walkie Talkies' or portophones are probably easier and cheaper though ;-)
I believe it is feasible and what would make it easier would be if you were to find a community of like minded people interested in "off grid" communication.
This is how I would set it up:
- Find someone to experiment with and who lives line of site to your home.
- Set up a WLAN using off the shelf radio transmitters. i.e. You point your respective transmitter/receivers to each other. I personally use a nanobeam.
- Transmitter is plugged into a PoE which is plugged into your router.
- You will need a private WLAN ip address range. Set up some routes either on your router or on your actual computers...
- Build your a simple rasberry pi cell phone tower
You may need to figure out how to limit the signal to the confines of your respective homes.
The RasberryPi will need to talk to your LAN, this is the piece of the puzzle you will need to solve.
And you will need to connect to the local cell phone network you create with your mobile device. And you wont need a sim card, they work just fine without them.
This is more or less how it would work:
**You -> mobile phone -> RPI -> LAN -> WLAN -> LAN -> RPI -> mobile phone -> friend**
Essentially no one will be able to plug into that network to listen to calls however you are limited to just calling your friend...
Where I am from we have a pretty big WLAN with almost 2000 people in it. We are networked every which way to sunday and essentially have our own private / dark internet. 2000 people have invested on average, $800 USD per AP, thats a $1.6 Million network spread over the community... and free to be run within our communities standards.
A rasberry pi mobile type network would spring up in much the same way and would rely on lots of people spending small amounts to build a free communication network. This is a project we are definitely going to work on.
Hope this encourages you to forge ahead.
At best this sort of thing is sketchy because of radio transmission regulations. Even ignoring that the project would be difficult. While the Pi can FM transmit, there's no receiver. You'd need to find a USB linux compatible one, or add on a USB sound card with audio in from a FM receiver. Then you'd need to make the transmission scripts, decode the received signal... there's a lot going on here. Better off to just buy or build a regular 2-way radio.