Updated 2019.04.21
Almost all SD channels are DD2.0. (DD2.0 sound can be processed by Dolby Pro Logic II or other DSPs in your AVR to produce surround sound, but is not DD5.1. For most TV sources, DPLII is the appropriate setting for DD2.0 or "stereo" or "two channel" signals)
Most programming on HD channels is now DD5.1. There are usually enough channels with DD5.1 that switching to various channels should get you a DD5.1 signal from one of them, just as a test to see if your equipment...
FAQ - What's Available in DD5.1
Almost all SD channels are DD2.0. (DD2.0 sound can be processed by Dolby Pro Logic II or other DSPs in your AVR to produce surround sound, but is not DD5.1. For most TV sources, DPLII is the appropriate setting for DD2.0 or "stereo" or "two channel" signals)
Most programming on HD channels is now DD5.1. There are usually enough channels with DD5.1 that switching to various channels should get you a DD5.1 signal from one of them, just as a test to see if your equipment...
FAQ - What's Available in DD5.1