Comment by HPsquared
8 hours ago
Reminds me of how every random electronic item would seemingly pick up audible interference from nearby GSM phones. Nonlinear components would involuntarily modulate the RF signal.
8 hours ago
Reminds me of how every random electronic item would seemingly pick up audible interference from nearby GSM phones. Nonlinear components would involuntarily modulate the RF signal.
When close enough, and especially when GSM antennas are mis-tuned it's perfectly possible to turn on the ESD protection diodes on low voltage inputs. For 1.8v IOs with weak current driven pull-ups you can trip the TTL threshold hysteresis.
I saw this once in a pre-production cell phone where tact-switch IO inputs were being spuriously activated. Figuring out that part of the UI required pushing physical buttons, suddenly made sense of "why do your batteries only last an hour".