Philadelphia-based Comcast has filed a federal lawsuit against DirecTV, saying its advertisements promoting some NFL games are misleading.The Comcast suit alleges DirecTV ads promoting its popular NFL Sunday Ticket service are misleading, The New York Times reported."As none of the ads disclose," the lawsuit said, "the offer is not for free NFL Sunday Ticket service -- the offer requires a two-year contract with hefty termination for early cancellation with the NFL Sunday Ticket service automatically renewing in the second year at full price."Comcast, the nation's largest cable operator, said DirecTV's radio advertising for the games doesn't mention the service's actual costs.Comcast said DirecTV's television and Internet ads "employ a carefully crafted scheme of purported disclaimers that were intentionally designed to deceive as many consumers as possible."Additionally, Comcast accused DirecTV of "falsely disparaging cable television service generally -- and by clear implication, Comcast's cable services specifically." Comcast called DirecTV a "serial offender" in false advertising.In a statement, DirecTV said, "We think it's deplorable that Comcast is trying to compete in the courtroom rather than in the marketplace."New customers who sign up for DirecTV can indeed get NFL Sunday Ticket at no extra charge for one year and there is no requirement to subscribe to NFL Sunday Ticket the following year. The last thing we want to do is mislead new customers."