[RFI] Digital TV Problems

[DGB]

I've recently had  subscribed to a service thru the fone lines that 
include TV and Internet. I've had the internet thru it for a long time.

I have 4 tv's in the house hooked to this system.

My shack is in a separate building but still about 30' from that problem 
tv. I've a good single point grounding system that is all connected to 
the tower, the service here in the shack, and the house's service. It's 
all connected undergnd with 2" copper and gnd rods every 16' (over 30 rods).

Recently I've been getting into the TV when xmtg but just one of the 
tv's. My signal scrambles the digital image, like tiling.

 I never had that problem when the tv had an outside antenna, even when 
running legal limit. I've put several clamps-ons on the problem tv. I 
also have a cat5 and telephone cable coming out here to the shak 
underground and have clamp-ons on them as well.

Where do I start?

Thanks ... 73 Dwight NS9I