I'm working on an app that passively picks up ultrasonic tones generated by SilverPush and sends out garbled data. The biggest issue with blanket interference across the entire ultrasonic band is that there are some legitimate uses that don't involve cross-device tracking. That's why we need to address this issue by selectively interfering with only known tracking schemes.
Do you have details on the encoding? I'm a bit suspicious of it being actually ultrasonic (device microphones often filter at 20khz or below) - seems more likely it would be audible spectrum noise with a ton of FEC.
[1] https://www.reddit.com/r/AskEngineers/comments/374876/lets_t... [2] https://vimeo.com/177586203