Your wireless mics frequency may need to change,
This was something that I wasn’t aware of until this week. If anyone uses wireless mics for your group or church, you may need to adjust your frequencies after the DTV transition is complete. I’ll be honest and say that I know very little about sound equipment, so maybe some of you tech-heads can clue me in with further details about how the new DTV channels will affect wireless signals.
More at the link, including a statement from Shure.