1. Zero Crossing 1.1. Purpose Locates one or all crossings of a given threshold in a signal. 1.2. Description Locates one or all crossings of a given threshold in a signal. The user may choose between all down crossings, up crossings or both up and down crossings. It is also possible to only select the first zero crosssing. If only the last crossing is wanted, this operation may be combined with a index selection operation ( using the last index option). 1.3. Input Equidistant and non-equidistant signals (see Signal Types ) are supported. 1.4. Output A non-equidistant signal in (x,y) pairs with the zero crossings