1mhz-200mhz FM Transmission with RPi

[fiery river]

im currently writing a program for the flipper which can interface with a raspberry pi zero w connected through the UART gpio loaded with https://github.com/markondej/fm_transmitter , so far ive been able to use my computer and the uart bridge to successfully transmit wav audio consistently around 100mhz. the range isn't very far (barely the next room).

tldr is there any good documentation for uart on the flipper? and if there isn't then where should i look in terms of source code? i want this to be a sort of standalone thing without the need of an extra computer

[plucky hornet]

whats the point to connect it to a rasperry pi

[fiery river]

i dont have any other hardware to transmit to that specific range. the radio chip included in the flipper cant transmit or receive below 300mhz

[urban laurel]

Doing this will likely create awful harmonics, it’s impossible to stay on a frequency you are allowed to send on/won’t cause too much harm if you send on it anyways

you might unintentionally interfere with all kinds of stuff (emergency services) if you do this without a filter on the antenna

[fiery river]

i tried it and holy shit you were right, i tried transmitting at 30mhz and i got the same signal at around 700mhz. the thing barely gets through to the next room even with an antenna so i don't think it'll be much of an issue

[rain blade]

Do you think that with GPIO and some FM reciver you could catch some radio signals?

[wind hemlock]

That's what rpitx is about. I think it sends the modulated signal straight as PWM to a given GPIO, so it's not using the cc1101 chip