Please explain how to fix a noisy ground.You could write a book on this! The reference almarg provided is an excellent and authoritative treatise.
The first steps include checking the existing grounds and neutrals. Are connections clean and tight? Is the grounding scheme sufficient? Often, adding additional ground rods to an existing system can improve results. This is often required by code when other electric upgrades are made.
It's also important to have all grounds at the same potential. There are devices that can help with that, such as the one from Synergistic Research. Dedicated lines offer potential benefit here, too.