We have the situation with our RF modem based project where, after two months of up time, one of our processes has fallen over and stopped part of the system working. What has happened shouldn't, a check should have been made before trusting a value, but the assumption had been that the CRC had been passed, so there was no possibility that there could be a problem....

So it looks like a possible DOUBLE or worse bit error crept in.

Thanks for all the references and tips. I will print them out and try and pick my way through the maths.

Steve