RDS is not a brand but a type of radio. RDS means Radio Data System and is used to provide certain functions to your radio e.g. Traffic Announcemnets, Radio Station name, etc. If it doesn't have a brand name then it will probably be the one that came with the car so a Nissan dealer should be able to supply the code if you supply your car's VIN and proff of ownership.
Terry
July 2006