I own two LG HDTVs. Neither of them are network capable, and they are not "Smart TVs". Both of these TVs allow you to set the time on them. It is generally displayed when the devices first turn on, but there are a few other times it will display the time. You can also use the time feature to let them turn on and off automatically and different times. The time feature has two modes: Automatic and Manual.
When I was on digital cable, the Automatic setting didn't work. I'm assuming there is a standard time signal that can be embedded in the broadcasts that the TV uses. In the IT world we have NTP servers to automatically set the date & time on our computers, so I imagine it's something similar. As I said, it never worked, presumably because my digital cable provider didn't embed that signal in their repackaged broadcasts.
As I mentioned previously, we finally cut the cable. I had noticed that the Info button just displayed "No Information Available" on the OTA broadcasts. I was mildly frustrated that I'd lost program guide info, but just assumed it wasn't part of the OTA signal. Well, last night I noticed that the Info button wasn't displaying the current time even though it was set on the TV so I went into the settings to poke around. On a whim, before manually resetting the time, I toggled the setting over to "Automatic" (hope springs eternal, right?). Imagine my surprise when it actually showed the correct date & time!!! Obviously, the OTA broadcast has some sort of NTP signal embedded in it.
Once I exited the configuration menu, I hit the "Info" button again. Imagine my further surprise when it displayed the current time, the current program name, the current program time slot (including a bar showing how far into the program it was) and the description of the current program.
So riddle me this. Why does changing the Time setting from Manual to Automatic control whether or not the OTA program guide information is displayed? The only thing I can come up with is that all of this information is embedded in the same side-channel of the broadcast. Disabling automatic time control tells the TV to not read that side-channel at all. When you're on digital cable, which provides its own program guide functionality, it's not a big deal at all. You never use the TV "Info" button anyway. A better design, to my mind, would be for the TV to always consume the program guide side-channel, and only set the time automatically if that option is turned on. There is no logical connection between program guide and the time setting for most casual consumers.
I'm just happy I accidentally stumbled across this, so I don't have to grab the TV Guide app to figure out what's currently playing.
The LORD bless you and keep you; the LORD make his face to shine upon you and be gracious to you; the LORD lift up his countenance upon you and give you peace.
Numbers 6:24-26 (ESV)