  A novel approach to detect anomalies in superconducting radio-frequency
cavities is presented, based on the parity space method with the goal to detect
quenches and distinguish them from other anomalies. The model-based parity
space method relies on analytical redundancy and generates a residual signal
computed from measurable RF waveforms. The residual is a sensitive indicator of
deviation from the model and provides different signatures for different types
of anomalies. This new method not only helps with detecting faults, but also
provides a catalogue of unique signatures, based on the detected fault. The
method was experimentally verified at the European X-ray Free Electron Laser
(EuXFEL). Various types of anomalies incorrectly detected as quenches by the
current quench detection system are analysed using this new approach.
