When you detect a long-range (wide and/or "fuzzy") signal on the Wave Scanner you want to try and center the brightest part of the signal at the top in the wave scanner because the sensitive area of the scanner is in a wedge-shaped area extending forward from the SRV (in the center of the display). With the signal centered and the SRV moving toward the target, as you close on the target the "wedge" will begin to narrow until you get a nice, bright, tiny signal in the middle front of the wave-scanner display. About the time that happens you should get a target return in the scanner display.

I find it easiest to land on the daytime/morning side of a planet and head toward the sunset in a more-or-less straight line. This way I maximize daylight and don't go over the same ground twice. o7