Cassinis antenna is pointed at the predicted specular point where the angle of incidence ( {theta }_{i} ) equals the angle of reflection ( {theta }_{r} ), measured from the local vertical. Right circularly polarized (RCP) signals were transmitted, and at least one of the NASA Deep Space Network (DSN) antennas on Earth captured the echo. At the surface of Titan, a left circularly polarized (LCP) component of the echo signal was generated, requiring the presence on the ground of two receiving channels. Complex samples of each receiver output were collected at 16,000 samples/s and stored for later processing. The purpose of this figure is to illustrate the geometry of the observations and distances on the coordinate axes that are not drawn to scale.
