A sensing system (11) includes a first radar sensing assembly (10; 3104, 3106; 4100, 4200) and an analysis system (18). The first radar sensing assembly (10; 3104, 3106; 4100, 4200) measures plural distances (12; 22, 30; 42, 50, 60, 70, 80; 4102, 4202) to a first target location (16) at different times using radar. The analysis system (18) receives the plural distances (12; 22, 30; 42, 50, 60, 70, 80; 4102, 4202) from the first radar sensing assembly (10; 3104, 3106; 4100, 4200) and quantifies movements of a target object (14) at the first target location (16) at the different times by calculating differences in the plural distances (10; 3104, 3106; 4100, 4200) measured by the first radar sensing assembly (10; 3104, 3106; 4100, 4200). The analysis system (18) generates one or more first quantified activity level values indicative of the movements of the target object (14) at the first target location (16) using the differences in the plural distances (12; 22, 30; 42, 50, 60, 70, 80; 4102, 4202) that are calculated.