You'll generally find them on any planet or moon. Land, Pick an easy to see celestial object such as a moon or nebula to use as a guide (or you can use the compass but this is easier) and drive straight for it. Always move toward your targeted celestial body in as straight line as possible, veering only to investigate the desired signal sources.
Put your sensor zoom at max range and look for 2 tight bands at the very top edge of the sensor, this will indicate a downed satellite. As you get closer to the satellite the bands will at first stretch across the top of the scanner and then get smaller. The signal can also fade out, shift or even disappear altogether as you close in on the satellite.
If you see a security fence around it ignore this as it is the wrong type of satellite. The fenced satellite, which is a downed Navigation Satellite, very rarely gives you data and will be round. You will sometimes find them without a security but that is pretty rare. The one you are looking for won't be round like a ball and won't have a fence around it. You will often find 2-3 times more of the Nav Beacon variety than you will of the other.
The spawn rate on the data giving satellites is low, but usually you can find them in about 20-30 minutes, if your search goes much beyond 30 minutes I would suggest you recall the ship and move elsewhere to restart the instance.
These types of satellites seem to be easier to find on uninhabited planets or moons as the inhabited ones tend to spawn a lot of mines and other buildings. I suggest that you pick a rocky type planet/moon as you can move faster across the surface with less spinout and such. I usually find them on open plains, rarely in the mountains.
A word of caution, do not attempt to farm the satellites by yourself as the drop rate for CIF is very low and it takes quite a bit of time to find several of the desired satellites.
