> Because it works by exploiting this leakage, Time Station Emulator works best with a built-in speaker of a phone or tablet.
> In some cases, wired headphones or earbuds may also be suitable.
> Higher-frequency harmonics are considered artifacts beyond the range of human hearing, so they are routinely suppressed by audio compression algorithms and better equipment.
> Bluetooth devices and audiophile-grade equipment are therefore less likely to work.
Then I thought about the new digital power meters which display time and date and other info in a loop ... and ok I concluded, that's probably down to the mobile link for timing ... until I recalled where I live around the time when the telco's upgraded, the meter lost it's link for a few months - since the power drops out nearly every week the meter once power was restored still had time down to minutes correct.