Aylar: March 2022

Smartphones use a second CPU and second operating system in their baseband modems. At the heart of every smartphone there is a baseband processor which contains a general purpose ARM processor and runs its own operating system . These operating systems are closed source and vulnerable to hackers.

The baseband processor converts the data to a signal that can be used to modulate the carrier frequency for transmission and vice versa . That signal is handed off to the RF processor, which may also be part of the baseband chip. See baseband, Passive Wi-Fi and C-RAN. Baseband Processor in a Tablet.

Baseband is firmware that controls all radio devices on the phone , including GPS, wi-fi, Bluetooth, NFC, cell data and voice, etc. because these functions are highly regulated and certified, they are separate from the main operating system. AP software version is characterized by the Android version and kernel version.

A signal at baseband is often used to modulate a higher frequency carrier signal in order that it may be transmitted via radio . Modulation results in shifting the signal up to much higher frequencies (radio frequencies, or RF) than it originally spanned.