Information on Titan's Surface From Cassini Radar Altimeter Waveforms
Résumé
We have examined range-compressed waveforms from the Cassini Radar operating in altimeter mode (Ku band, bandwidth 4.25 MHz, nadir pointing) during observations of Titan. We find that leading edge detection provides a straight forward determination of a maximum surface height. The heights from the set of observations give a mean radius of Titan about 0.5 km larger than the nominal 2575+/-0.5 km determined from Voyager. The altimeter footprint diameter is about 25 km on the surface and thus represents an average over the terrain. The waveforms are complex beyond the leading edge. We have performed simulations over various sized dunes and other terrain and find reasonable agreement with the signal observed from several regions, consistent with the published report of dunes. We have developed several measures of waveform width and complexity to characterize the surface. We display the consistency among these measures and compare them to other characterizations of the surface.