[LeonM]

From the linked repo:

> rpitx is a general radio frequency transmitter for Raspberry Pi which doesn't require any other hardware unless filter to avoid intererence. It can handle frequencies from 5 KHz up to 1500 MHz.

Wait, how does that work?

1.5GHz is a _lot_, I can't imagine this is done with bit-banging an I/O line, nor do I expect the Pi will have a DAC with anything close to a 3GHz+ sample rate.

> Plug a wire on GPIO 4, means Pin 7 of the GPIO header (header P1). This acts as the antenna.

A bit of Googling shows me that on the later Pi board GPIO4 (pin 7) has a bunch of alternative modes, amongst which is a general purpose clock output (GPCLK0), a DPI output bit (DPI_D0) and what I recon is composite analog video in/out (AVEOUT_VID0, AVEIN_VID0), and the TDI JTAG pin. But none of these would get close to 1.5Ghz TRX capabilities, no?

What's the magic here?

[solarist]

RF is basically black magic but here it’s the harmonics of lower frequencies that are in GHz range (and very noisy and weak)