Always use blind scan when scanning true FTA channels.
How to avoid getting huge amounts of encrypted channels, usually Dish or Bell (SR 20000):
For example G17 and Nimiq 1,4 are located at 91W spot. Although one is circular and the
other is linear, using universal LNB will scan both and you end up with numerous channels
that are useless to you.
To avoid this, there is a setting in the scan menu called "FTA Only", something similar
to that, may change from one receiver to another, select that and although the scan will
take longer, you only end up with non encrypted channels.