Once again thanks for all the replies.

Perhaps I am going over the top. What I want is a RELIABLE transmission over long range RF modems, transmitting in the permitted UK bands over a distance of about 2km. The modems can transmit at up to 9600 baud. The channel allocation of the available band is so restricted I cannot guarantee that there won't be anyone else trying to send something at the same time, though only for a fraction of a second (the channels are not licensed for continuous transmission)

The intelligence in the signal is very low, and I have a lot of time to receive it, hence my ideas of error correcting codes.

In the scenario I describe, is ECC the way to go. I'm sorry my comms knowledge is so basic, but its a long time since I did any courses on it at all !!

Thanks again

Steve