Using the 800/900Mhz frequencies on Android device

Let's say I have an Android device which supports GSM 800/900Mhz bands and I want to use it as a transmitter to remotely control a car or anything else. Is it possible to program such a thing on Android ? Maybe using NDK ? The purpose would be to send custom packets on these frequencies.

Thanks.

Solution

There are a lot of misunderstandings in this concept, however what you're thinking of quite nice, assuming it would be possible (which isn't :( ).

RF communication is handled EXCLUSIVELY by the modem software, which is included in the baseband binaries.

You cannot simply tap into it, and send whatever you like, since the protocol and its transport layer are very strict to comply with the GSM rules. Also - since baseband binaries are under strict control there are very few, to none custom ones.

There are also WAY many other reasons why this is not actually possible, without lots of hackish work. Those devices are made strictly to perform on the GSM network. You could use another reciver to for example send WAP push messages (in raw form) as commands, however expect the delays to be HUMONGOUS (ie. 1second - 20 seconds) which is not viable for any kind of remote control. Same results as SMS communcation, just in an unrestricted form.

CAUTION: Using telecom broadband channel is BANNED for public use in most countries, so even if you get an external GSM bands transmitter (which actually can be done), you still would need to comply to your countries regulations.