I noted - > Capacitive coupling also worth thinking about. but I don't think that anyone picked up on that. It is easily implemented [tm], low cost and will easily achieve the data rates desired. The stated range requirement would be getting very hard to meet, but if a much smaller range was tolerable then it may provide a very good fit to the requirement. Russell --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .