In the disclosed distance measuring arrangement, a light projector turns on and off to illuminate an object over the ambient light during projection periods when light is projected and during space periods when light is not projected. The reflected light is detected as a function of distance by integrating projection signals representing light reflected during projection periods, integrating space signals representing light during reflected space periods, subtracting the integration space signals from the projection signals, and extracting measurements based on the subtractions. Compensation for change in ambient light between periods is obtained by changing the timing of the integrations and extractions from concidence with the projections and space periods.