i just got my vip211 and dish100 hooked up on sunday. my signal strength on sat 129 fluctuates between 64 and 80 (i live 40 miles north of houston,tx). why does it fluctuate so much, and at what point will my picture start to pixelate and go out. i thought i heard someone say as long as it stayed above 50 you're ok, but i just want to make sure. thanks.