If you are using a set top box or
getting free channels only, the
signals will be "grainy" in higher
You should complain to your Cable TV
He can install an amplifier for your neighbourhood.
( Broadband amplifier VHF say 50 MHz to 300 MHZ)
OR you can use your own.
Cable TV=== different cables=== Amplifiers===> 4 way splitters
see this link for reference ; Amazon.com: Motorola Signal Booster 1-Port BDA-S1 Cable Modem TV HDTV Amplifier: Electronics