A first source of an electromagnetic signal is configured to illuminate or radiate the evaluation channel through which a series of particular seeds pass. For example, the electromagnetic signal comprises a pulse with at a primary reference phase and primary reference magnitude. A first receiver of the electromagnetic signal comprises a detector to determine or identify a first seed-related characteristic (e.g., first seed characteristic) based on an observed primary phase and an observed primary magnitude. For instance, a seed treatment device is configured to treat or spray discharged particular seed with a seed treatment based on the estimated characteristic, or to reject non-conforming seeds that do not meet seed specifications.