Is it a false alarm?

The term “false alarm” is widely used when discussing radar performance and this leads to the implicit assumption that we all know and agree what is meant by a false alarm and that the term has constant meaning. Other than the simple case of noise, this is however rarely the case. The author suggests that the term “false alarm” does not have a constant meaning but is scenario dependent. For a specific radar on a specific site it may have a different meaning in different parts of the coverage or at different times. Specifying the false alarm rate of a radar is therefore very difficult and proving compliance is almost impossible. Even where specification and compliance are achievable, the relevance to the real world is questionable. In practice, a radar is installed on site and a period of optimisation begins where the user and the designer agree on an acceptable balance between wanted detection and unwanted detection