On Mon, 12 Jan 1998, C. Muehlbach wrote:

> Hello all,
> 
> i should realize a RF data transmission with 8 or 12 parallel bits, I
> whanted to use the MM57C212 Coder/Encoder from National, but this part is
> replaced by a COP87L42CJ.But I couldn«t recieve this COP in Germany, there
> is a little problem with National.
> So I thought of using a PIC for the Coding/Encoding, the RF module can
> handle frequencies between 300 Hz and 5 KHz.
> So my question is there anywhere an application known or a bit of code
> which could be useful for my application, or has anyone a source for the
> desired National parts.
> 
> 
>  Christopher MŸhlbach
> 
> 
Christopher,

I have recently started playing around in this area for a work project. 
I am using some 2 terminal 418MHz A.M. Tx / Rx pairs that are designed
for car door locks.
At first I just tried sending ASCII at 1200Baud, but I got a lot
of false triggers due to noise pickup in the receiver.
Now I am using a pulse width modulation, sending 3 bits per data
bit at 1200 bits/second, giving me a data rate of 400 bits/second.
This is encapsulated into a 32 bit packet (8 check bits).
So far this has been quite reliable.

Pete