The basic idea is to have an audio transceiver in various rooms of my house. Each should have buttons like Room 1, Room 2, and so on. Pressing a button and speaking should result in the corresponding receiver receiving the voice signal. Full duplex is not necessary. Frequency range is not important. Would rather avoid (obviously) the 88-108 MHz FM. Range need not be more than 200 metres LOS. I would like some ideas to start going about making this project.
I searched on the forum and Google for wireless intercoms and such, but couldn't find any satisfactory results.
Thanks!
Don't think "DECT" phone systems are available here. Is it really that tough to make? Non FM broadcast band is a must, but secure frequency, in terms of eavesdropping, is not that important.
93 different ads for "DECT" phones on ebay India. You probably have other sources if you look in the right places.
To build your own, you first have to find a suitable license free band which is still empty, and then design a protocol to alert one handset and not the others, and build the transmitters and receivers.
If you have anything like the "family radio service" like we have in the States, those transceivers would be ideal.