I'm trying to create a simple NFC/RFID software simulator and am having a hard time understanding the math fully. I know that NFC tags respond by load modulating the 13.56 MHz wave that the reader is sending it. I'm pretty sure NFC tags use a subcarrier wave with a frequency of ~847 kHz. Where I'm getting confused is how to model the result of the load modulation.
Can I simply take the 13.56 MHz wave and do a point-wise multiplication with the 847 kHz wave? Using the Manchester Encoder, this nets me a signal that looks like this: