Performance Prediction and Verification for the Synchronization Link of TanDEM-X

The paper describes the synchronization link of the two satellites of the TanDEM-X mission. The synchronization link is established to track the oscillator phase noise difference which —after appropriate processing— can be used to compensate the effect of oscillator phase noise. A signal model based on the synchronization link hardware is presented which is then used to derive an analytical expression for the compensation phase including effects such as instrument drift, Doppler, antennas, and receiver noise. Specifically the influence of the synchronization link RF hardware on the quality of the derived compensation signal is crucial for the performance. Therefore the synchronization link RF hardware of the TerraSAR-X satellite is characterized to obtain realistic data. These measurements will be used for the calibration of the synchronization link, i.e. to remove systematic errors due to temperature drifts of the instrument.