Delete comment from: Ken Shirriff's blog
I would love to know if you have more information about this:
"In more detail, the reader transmits at a carrier frequency of 13.56 MHz.10 To send data back, the tag switches its load on and off at 848 kHz (1/16 of the carrier frequency), producing a subcarrier on top of the reader's signal."
Mainly my question is: how can the chip modulate at a lower frequency without having an internal clock? Or does it detect and count the periods in the received signal?
Or does it contain an oscillating circuit for that lower frequency which acts as a passive clock?
Jun 30, 2024, 8:49:41 AM
Posted to Inside the tiny chip that powers Montreal subway tickets