The tvtime-scanner generates a list of channels of whatever it finds, but it is annoying to have “No Signal” blue empty channels in between those that are actually broadcast.
To have tvtime skip these channels, use this command once tvtime is up and running:
$ tvtime-command CHANNEL_SCAN
Reading configuration from /etc/tvtime/tvtime.xml
Reading configuration from /home/viulian/.tvtime/tvtime.xml
tvtime-command: Sending command CHANNEL_SCAN.
It will cause tvtime to check if the channels really have signal or not and drop those which don’t.