audioguru said:
They look awfully simple and cheap. I don't think their frequency will be stable. It will probably change with the temperature, supply voltage and if anything gets near the transmitter or near its antenna. :cry:
They are licence free modules, and as such have to comply with the fairly strict requirements of the licence free status.
The transmitter is probably actually entirely inside the round can?, it's quite commonly done like that - and the 'round can' is small enough to fit inside a key remote.
The receiver might well be a super-regen, these are often used on the cheaper units, although for slightly more money you can get supethet ones. I 'think' the one I've got in my hand at this second is a superhet?, at least it has a fairly large surfacemount IC (30 odd pins?, too small to count!) and a crystal or filter on board.
Stability of the modules is improved by being built on a ceramic substrate (like mine), but I notice that the ones in the link are just PCB.
But they should be fine, superhet's give better range, but they are only intended for short range use anyway.
ronjodu:
You can't just send RS232 type serial data over the link, because they are AC coupled - if you invert the data at each end (so resting state is LOW - not HIGH), then it can work. But you're better off using a proper encoding scheme such as Manchester coding.
I'm currently working on just such a tutorial, based on the routines from
http://jap.hu/electronic/codec.html.
If you try the BASIC from
**broken link removed** I understand it includes Manchester routines?.