could be anything from LNBF problem to connector problem
first check all the barrells in the line, barells are the connector used to connect two cables together mainly found by the dish in the J box outside your house or inside the wallplate by your receiver u wanna make sure its 3 ghz most of the 3ghz rated barells are blue inside then you wanna check the cable make sure its not bent nothing is shorting the cable like a staple on it under the eve or by the board to the bottom of the wall in some cases and if the cable is run under the carpet make sure no nails are going through it i personally dont run sat lines under carpets TV2 uhf isnt a problem though connectors should be checks as well see if any metalic hairs from the sheild is touching the copper wire in the connector check if the copper wire is too long or too short if everything is ok u need to change the LNB, pixelation sometimes if its only on one of ur receivers could be due to a bad receiver its very unlikely though!!