Glossary for Geospatial Science

SAR:� Synthetic Aperture Radar.� SAR uses a microwave instrument that sends pulsed signals at targets and processes the return signals that it receives.� The SAR sensor can function day or night and regardless of weather conditions.� SAR differs from other radar imaging processes because it synthesizes a greater antenna length than actually exists.� Signals received and recorded by the radar system as it moves along its flight path are Doppler-shifted.� By comparing the Doppler frequencies to a reference frequency, many of the returned echoes are focused on a single point effectively increasing the length of the antenna that is imaging on that point.� Very precise knowledge of the relative motion between the sensor platform and the imaged objects is required.