Simulation of tracker performance in SARIn mode over topographic terrain and under extreme conditions. This example shows loss of track and recovery.
In SARIn mode, the instrument transmits busts of pulses with alternating bandwidth of 40MHz and 320MHz.
The low resolution pulses (40MHz) are only used on board for tracking to adjust in real-time the position of the window and keep the leading edge of the echo inside the window. The corresponding echoes are shown on the top. High-resolution echoes (320MHz) are sent to the ground and constitute SIRAL measurement.
In both cases, only the part in red is exploited by the instrument, the part in blue is filtered out and lost. The solid vertical lines materialise the limits of the windows. It can be seen, that when the shape of the echo changes rapidly, it cannot be kept inside the limits of the corresponding windows. However, after a while, the tracker is able to recover and brings the leading edge of the echo inside the window.