How do I find gap in sqlite table?

I have a sqlite table with timestamps in milliseconds as primary key each row should be 1 second or 1000 apart from one another. Sometimes my data recorder goes out and there is no data in the table for that time. How can I find the gaps using a SQL statement? A cursor based solution is possible I know.

TS
1119636081000
1119636082000
1119636083000
1119636084000
1119636085000
------gap------
1119636090000
1119636091000