The pulsed ground point at the greatest distance normal to the flight path fixes the far range . The depression angle decreases outward from near to far range. Pulse travel times increase outward between these limits. The duration of a single pulse determines the resolution at a given slant range. This range resolution is effectively the minimum distance between two reflecting points along the azimuthal direction that the radar can identify as separate, at that range.
Range resolution gets poorer outward for a specific pulse duration.
The duration of a single pulse determines the two types of resolution at a given slant range. The pulses undergo varying degrees of backscattering when they reach an object. In effect, the smooth surface reflects most of the signal away, so that its image expression is dark. A rough surface, in contrast, scatters the pulse beam over many directions, a fraction of which returns to the radar. The amount of returned signal determines the relative lightness of the image tone.