[throw0101b]

> Wouldn't this invalidate the FCC certification on the prebuilt modules?

MAC is at OSI Layer 2. FCC concerns about radio power occur at the PHY layer, OSI Layer 1:

> On the ESP32, the PHY layer is implemented in hardware; most of the MAC layer is implemented in the proprietary blob. One notable exception to this separation is sending acknowlegement frame: if a device receives a frame, it should send a packet back to acknowledge that this packet was received correctly. This ACK packet needs to be sent within ~10 microseconds; it would be hard to get this timing correct in software.

* https://pics.zeus.gent/vYXyQm2t9pJCzpDdWFvq9oWR2DACoUJoTsYf8...

[crote]

It's not that simple. Besides implementing a SoftMAC, the blob is also responsible for setting up the PHY, so it would definitely be able to adjust things like transmitting power. See the part describing `esp_phy_enable()`.

[rkfjrjrkfnrkd]

If you know where to look, I'm quite sure you can already do this with vanilla ESP-IDF. I don't have a VNA or whatever is used to measure power at the antenna, but I do have a precision ammeter that confirmed my changes were effective at the supply. I only changed PHY power parameters and a lot more power was going somewhere.

Also, in my limited understanding, even changing the physical antenna can alter transmission power characteristics in such a way that it likely violates some limit, at least for some very specific wavelength or direction.

[calamari4065]

Huh, neat!