Forward scatter sensor

A forward scatter sensor for precipitation analysis, the forward scatter sensor comprising:

• a transmitter arranged to emit a light sheet;
• a receiver offset from a propagation path of the light sheet and arranged to observe light scattered from particles that fall through a measurement volume defined by an intersection of the propagation path of the light sheet and a field of view of the receiver;
• and
• a control entity comprising an analyzer arranged to record a measurement signal that is descriptive of intensity of light captured by the receiver as a function of time, wherein the analyzer is further arranged to:
• carry out a precipitation analysis on basis of a time segment of the measurement signal, the precipitation analysis comprising identifying, in said time segment of the measurement signal, one or more double peaks that each represent a respective droplet and comprise a first peak that represents light refracted from a bottom of the respective droplet upon entry to the measurement volume and a second peak that represents light reflected from a top of the respective droplet upon exit from the measurement volume and estimating respective droplet sizes based on said one or more double peaks;
• carry out a verification of analysis performance based on magnitudes of first peaks of at least one identified double peak and on respective residence times for said at least one identified double peak, wherein the residence time for a given double peak is defined by a time difference between the first and second peaks of the given double peak, wherein said verification comprises deriving respective first estimated sizes for droplets represented by said at least one identified double peak based on magnitude of the first peak of the respective double peak and deriving respective second estimated sizes for the droplets represented by said at least one identified double peak based on a residence time indicated by the respective double peak, wherein the residence time is defined as a time difference between the first and second peaks of the respective double peak;
• and
• invoke a predefined maintenance action in response to said verification indicating a threshold-exceeding difference between said first and second estimated sizes.