In a method for monitoring a measurement system having a transmitter which determines the position of a moveable element and has a transmitter clock, and an electrical energy store which, in the event of a failure of an external electrical supply voltage for the transmitter, continues to supply electrical power to at least a part of the transmitter, including the transmitter clock. The camera comprises a layer of scintillating material, a fiber optic face plate block, and an array of image sensors. The supervisory device also uses the messages and minislot counts to anticipate bursts from the remote devices.