For those outside the Boston area (or unable to get WCVB in Canada), and also without the DirecTV Sunday Ticket or a Slingbox set up somewhere in New England, here's the national television schedule.
Pre-Season
Week 2, 8/17, 8pm at Tampa Bay on NFL Network
For the regular season, it really depends on where you are. If I'm not mistaken, it depends on two things: which network (CBS or FOX) owns the "doubleheader" that Sunday, and when the team in your local market is playing that day. For example, if you're in Miami and the Dolphins are playing at 1:00, then the only way you'll see the Pats is if they're playing at 4:00, and then only if CBS own the doubleheader on that weekend. But if you're in San Diego and the Chargers are playing a late game, you might get the Pats on local TV for the early game. The only sure things are (1) the week 6 game Sunday night game at San Diego, (2) week 7 Monday night game vs Denver, (3) week 9 Sunday night game at Indy, (4) week 11 Thursday night game vs the Jets on NFLN, and (5) week 14 Sunday night game at Seattle.
NBC could also add more Sunday night games if they wanted to with the flex scheduling that allows games to be moved after week 11.
This link shows which weeks FOX owns the doubleheader. The only Pats games you might see on FOX are 10/26, week 8 1:00 vs St Louis and 12/21 week 16 1:00 vs Arizona. If you live in the primary market of an NFC team you'll probably never see the Pats on FOX - unless the local team is on a bye or playing a night game that week - and will need to hit a sports bar on the weeks FOX owns the doubleheader: weeks 1, 4, 6, 8, 9, 12, 14 and 16.
Here are the weeks that CBS owns the doubleheader, and who the Pats play that week.
Week 2, 9/14, 4:15 at Jets
Week 3, 9/21, 1:00 vs Dolphins
Week 5, 10/05, 4:15 at 49ers
Week 7, 10/20 - Pats on MNF vs Broncos on espn
Week 10, 11/09, 1:00 vs Bills
Week 11, 11/13 - Pats play Thursday night vs Jets on NFLN
Week 13, 11/30, 4:15 vs Steelers
Week 15, 12/14, 4:15 at Raiders
Week 17, 12/28, 1:00 at Bills
Again, it depends on who the team is in your local market, when they play that week (or if they have a bye). The most likely games are those four 4:15 games. So it looks like the Pats will be on TV outside of New England probably about nine times this year, plus once in the pre-season - including a pre-season and regular season game on NFL Network (which you may or may not get.)