A sensor encoder was a special device that was developed and used by Xindi-Reptilians. They were found somewhere aboard their ships and kept sensor records. In the event a ship was destroyed, the encoder was ejected and floated in the debris field. If the crew's superiors received no communications, an analysis team would be dispatched to find the encoder and find the cause of the ship's destruction. An encoder from a Reptilian scout ship revealed that the ship was destroyed by Degra, giving Commander Dolim ample reason to murder him. (ENT: "The Council")