The smart televisions are far more likely to have code (or be updated with code) that can be used to emit unique tracking signals of some sort.
Sorry if I'm missing something, but television programming usually doesn't require code in the TV in order to emit audio. Is audio in ultrasonic frequencies a special case?
Although I can't confirm this myself, a few people here have mentioned that its likely that a digital TV signal's audio track would be compressed to remove inaudible ranges. This would require that any ultrasonic data be added by the TV.
From what I can tell, HDTV audio is typically sampled at 48kHz and compressed with AAC using spectral band replication (SBR) techniques. I'd definitely say it's plausible that signal could contain stuff outside a normal adult's hearing range.
AFAICT Yatenfou is saying that the ultrasonic tracking beacon is done by software on the smart TV and not actually part of the television signal.
The risk with smart TVs is (as an example) CBS approaches Samsung and asks them to push code that makes the TV do a particular hard-to-notice sound when it detects the logo of a specific show being sent to the screen.