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This paper focuses on the extensive analysis on the characteristics of the echo phase of INterferometric Synthetic Aperture Altimetry (INSAA) using the “random background plus a strong scatter” model, and it can be a good manifestation of the potential applications of INSAA. The works in this paper may bring benefits not only to interferometric altimetry, but also to other interferometric radars.
An airborne delay Doppler altimeter was flown in autumn 2014. A calibration suite including a GNSS buoy, two tide gauges and two GPS stations were established. An experiment was carried out to test the GNSS buoy as a whole under dynamic ocean condition, to validate its performance and accuracy via the inter-comparison of tide gauges, and to demonstrate the altimetry calibration methods and to estimate...
GNSS buoys are innovative ocean instruments, and can provide calibrations of the sea surface height and significant wave height (SWH) products of satellite altimeters. This paper investigated the principles of the wave retrieval by GNSS buoys, and proposed a method of calibration of altimeter SWH product by GNSS buoys. The error sources in the calibration procedure were analyzed. Ocean calibration...
This paper tries to establish a relationship between the AGC (Automated Gain Control) value and thermal noise level in satellite altimetry. The motivation is that: in the non-ocean situation, the noise floor level may be too high to be reasonable, especially in C-Band as we would see. This may occur from the ground surface echoes which enter the noise gate. In the re-tracking procedure if the improper...
In this paper a transponder system dedicating for the on-orbit calibration of the two primary active microwave sensors: radar altimeter and radar scatterometer are designed. The three major parameters: the height measured by the altimeter, and the backscattering coefficient measured by the altimeter and the scatterometer can be fulfilled in the same system. The transponders proposed in this paper...
Satellite radar altimeters play an independent role in ocean remote sensing, while the authors exploited their potential in rain measurement. This paper designs the digital system of the rain mode in an altimeter. In rain mode the altimeter receives the ocean and rain echoes simultaneously, so it can retrieve the rain layer profile without losing surface topography information. An adaptive IF-digital...
Satellite radar altimeter plays an important role in microwave remote sensing, but its performance and applications on non-ocean surfaces are constrained by its poor resolution. The along-track resolution of altimeters can be improved by the synthetic aperture technology, while the cross-track resolution can be improved by the interferometric technology. Although these two technologies are well-established...
Satellite radar altimeters are fundamental tools in microwave remote sensing, but traditionally they were regarded as unsuitable for rain measurement. This paper designs a rain mode on an ocean-dedicating altimeter, taking China's forthcoming HY-2 ALT as a typical example. In rain mode the altimeter receives the surface and rain echoes simultaneously, so it can estimate the rain layer structure without...
In this paper, the characteristics of the alpha-beta filter in altimeter height loop are analyzed. The "acceleration lag bias" is firstly described and the previous approaches are reviewed, and then, an innovative algorithm is designed to compensate the error. Finally, a numerical simulation is presented to test the effectiveness. It is shown that bias can be almost totally compensated by...
A theoretical analysis of the altimeter split-gate height tracker error is carried out in this paper. The principles of altimeter split-gate tracker are reviewed, and the discriminative curve of the tracker is derived. It is shown that the antenna parameters have little influence on the slope of discriminative curve. The height noise of the tracker is analyzed, assuming there is no other noise in...
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