Why is the precision of PS displacement velocities in the order of millimetres and the precision of their heights in the order of decimetres?
The precision with which displacement velocity and heights are retrieved depends from the very physical model explaining the phase values registered by the satellite sensor. The phase of the microwave radar signal registered by the sensor is the sum of many components: a phase due to the elevation of the Earth surface, a phase due to displacement movements and phases due to other contributions. The phase due to the elevation of the surface is linked to the difference in look angles between the master and slave image and to the normal baseline between the two images. The smallest detectable variations in look angles and normal baselines result in measurements of elevation in the order of decimetres. The phase due to displacement movements is proportional to the distance between the satellite and the ground and the smallest detectable variations in this distance result in measurements in the order of tenth of millimetres.
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