A low-cost compact active transponder to facilitate SAR Interferometry
SAR interferometry (inSAR) has been proven to be a very accurate way to measure very small (sub-centimetre) amounts of vertical movement at regular intervals. Examples of applications for which this has been used are:
- Identification of the precursors of subsidence and landslides;
- Volcanic eruption and earthquake prediction;
- Identification of unauthorised tunnelling or construction.
Normally such approaches suffer from the problem that suitable targets (so called corner reflectors) must be visible to allow the processing. This means that distinct radar visible features need to be present or deployed on site.
REFLEcX, SEA’s low cost compact active transponder, has been developed to solve this problem. The lightweight active system, transmits a signal back to the satellite which the satellite interprets as if it were a small, highly reflective object on the ground; the perfect inSAR target. Because the transponder is only turned on at the time of the satellite overpass it offers much less interference to other radar or radio systems targets than conventional corner reflectors.
Many such transponders can be deployed in an area of interest to provide a detailed picture of changes in the ground, which may be the pre-cursors to natural disasters.
Applications
- civil engineering
- land surveys
- geophysical surveys