The figure above shows four panels, each of which portrays depth profiles derived from processing radar ice sounding data by a particular algorithm. In each panel, the vertical axis shows increasing time delay from top to bottom, scaled to correspond to depth in meters within the ice sheet. The horizontal axis shows the along-track position of the sounder. The color scale represents power in the output waveform, according to the scale shown at the right hand side of the figure. In all cases, the power has been normalized so that the brightest pixel in the frame is set to zero dB.
The 150 MHz sounding radar [Gogineni, et al., 1998] is mounted in an aircraft
flying at several hundred meters above the ice sheet. The radar is coherent
pulse-to-pulse. In all panels, the output waveform at each along-track position
is the result of an integration over a group of input waveforms in the along-track
direction. The principal difference between the algorithms is the specific
way in which that integration is done. In these examples, each group consists
of 32 pulses. As a result of amplitude normalization, which has been done
to render effective graphics, these illustrations do not convey a comparison
of the relative signal levels as a function of processing algorithm.
The processing results illustrated may be viewed as a progress report in the course of an on-going project. We are grateful for access to original data records from a major data collection campaign [Gogineni, et al., 1998], and for the encouragement and support of Prof. S. Gogineni and his colleagues.
References
[1] Gogineni, S. P., J. Legarski, and R. Thomas, Coherent Radar Depth Sounder Measurements Over the Greenland Ice Sheet, Proceedings IEEE Geoscience and Remote Sensing Symposium IGARSS'98, Seattle, WA, July 1998, pp. 2258-2260.
[2] Raney, R. K., Delay Compensated Doppler Radar Altimeter, U. S. Patent No. 5,736,957, Issued April, 1998a.
[3] Raney, R. K., The Delay/Doppler Radar Altimeter, IEEE Transactions Geoscience and Remote Sensing, Vol. 36, No. 5, Sept. 1998b, pp. 1578-1588.