Name
Abstract | ||
|---|---|---|
The concept of delay/Doppler (DD) altimetry (DDA) has been under study since the mid-1990s, aiming at reducing the measurement noise and increasing the along-track resolution in comparison with the conventional pulse-limited altimetry. This paper introduces a new model for the mean backscattered power waveform acquired by a radar altimeter operating in synthetic aperture radar mode, as well as an associated least squares (LS) estimation algorithm. As in conventional altimetry (CA), the mean power can be expressed as the convolution of three terms: the flat surface impulse response (FSIR), the probability density function of the heights of the specular scatterers, and the time/frequency point target response of the radar. An important contribution of this paper is to derive an analytical formula for the FSIR associated with DDA. This analytical formula is obtained for a circular antenna pattern, no mispointing, no vertical speed effect, and a uniform scattering. The double convolution defining the mean echo power can then be computed numerically, resulting in a 2-D semi-analytical model called the DD map (DDM). This DDM depends on three altimetric parameters: the epoch, the sea surface wave height, and the amplitude. A multi-look model is obtained by summing all the reflected echoes from the same along-track surface location of interest after applying appropriate delay compensation (range migration) to align the DDM on the same reference. The second contribution of this paper concerns the estimation of the parameters associated with the multi-look semi-analytical model. An LS approach is investigated by means of the Levenberg-Marquardt algorithm. Simulations conducted on simulated altimetric waveforms allow the performance of the proposed estimation algorithm to be appreciated. The analysis of Cryosat-2 waveforms shows an improvement in parameter estimation when compared to the CA. |
Year | DOI | Venue |
|---|---|---|
2014 | 10.1109/TGRS.2013.2280595 | IEEE T. Geoscience and Remote Sensing |
Keywords | Field | DocType |
Doppler radar,antenna radiation patterns,convolution,least squares approximations,ocean waves,oceanographic techniques,probability,radar altimetry,radar cross-sections,remote sensing by radar,synthetic aperture radar,transient response,2D semianalytical model,Cryosat-2 waveform,DD map,DDA,FSIR,Levenberg-Marquardt algorithm,along-track resolution,along-track surface location of interest,altimetric parameters,altimetric waveform,amplitude,circular antenna pattern,conventional altimetry,delay compensation,delay-Doppler altimetry,double convolution,flat surface impulse response,frequency point target response,least squares estimation algorithm,mean backscattered power waveform,mean echo power,measurement noise,multilook model,parameter estimation,probability density function,pulse-limited altimetry,radar altimeter,range migration,sea surface wave height,specular scatterers,synthetic aperture radar mode,time point target response,uniform scattering,Altimetry,Cryosat,delay/Doppler (DD) map (DDM),least squares (LS) estimation,synthetic aperture radar (SAR) altimetry | Radar,Least squares,Impulse response,Doppler radar,Convolution,Synthetic aperture radar,Remote sensing,Algorithm,Radar altimeter,Estimation theory,Mathematics | Journal |
Volume | Issue | ISSN |
52 | 7 | 0196-2892 |
Citations | PageRank | References |
10 | 0.81 | 9 |
Authors | ||
5 | ||
Name | Order | Citations | PageRank |
|---|---|---|---|
| Abderrahim Halimi | 1 | 292 | 20.72 |
| Corinne Mailhes | 2 | 99 | 20.48 |
| Jean-Yves Tourneret | 3 | 1154 | 104.46 |
| Pierre Thibaut | 4 | 39 | 13.51 |
| Francois Boy | 5 | 30 | 5.15 |