adil is spot on in his advice. If you use a sig booster you might blast the signal off the box, in other words you might not get a good picture at all.
The cable providers and sat guys pad the signal down when it is to strong so that it does not have this effect. It's akin to living next door to a terrestrial services mast where you might not get a picture on your tv at all. They like the sig to be about 60% strength for good reception.
Try Andromeda 2.0 which is a magic image and may well resolve you problem.