4 ms·
> infrared fobs Wait, what? You have to point a powered device at an IR receiver and press a button like a TV remote? I've never seen a building entry system
by happyopossum 2y ago
> infrared fobs
Wait, what? You have to point a powered device at an IR receiver and press a button like a TV remote? I've never seen a building entry system like that!
- __MatrixMan__ 2y agoThat's probably because it's not so good as a building non-entry system.
- psobot 2y agoExactly that, yes! IR receivers outside every exterior door to the building, and IR receivers in the elevators to control access on a floor-by-floor basis. The fobs were visible by an IR camera (including the average smartphone) and could trivially be decoded as a short bit sequence with an IR sensor wired into a microphone jack, as the bit pattern was transmitted at ~audio rates.