The Space-Based Altimeter Echo-Signal when Doppler Scattering is taken Into Account

Abstract

In the analytical approximation of time dependent average power of a satellite altimeter echo-signal (power profile) the Doppler scattering of individual specular point responses is usually neglected. Meanwhile, in the modern Ka-band altimeters the Doppler shift of reflection from a point near illuminated spot edge is greater than the frequency resolution. The equation for the power profile allowing for the Doppler effect is derived. While, as expected, the profile leading edge is not influenced by the Doppler shift, there is critical discrepancy in the trailing edge behavior between ranging LFM and BPSK signals. If for the former the Doppler shift involvement does not change trailing edge steepness for the latter it makes the profile decrease much faster. Finally, the possibility to utilize the Doppler scattering to improve along-track altimeter resolution is discussed.

Keywords

• satellite altimeter
• echo-signal
• doppler scattering
• lfm-signal
• bpsk-signal
• synthetic aperture