By designing the schematic and PCB of ymfc-mini-drone, I’ve also acquired the knowledge of designing a SDR board, and I have recently designed and tested my own version of RTL-SDR.

As an SDR hobbyist, designing my own board and firmware is much more satisfying than playing with existing software in user space. By sharing this project, I hope more SDR hobbyists will benefit from it.

Earlier this year, I developed several apps on Portapack. It’s an extension board for HackRF, to run it without a PC.

The apps I made mainly deal with communicating with drone radio equipment, including GPS transmitting, PAL demodulation(analog video), BLE decoding and NRF24L01 decoding (the control signal commonly used for mini drones).

I developed those apps by combining the knowledge of digital signal processing from the SDR world and microcontroller developing I acquired from this YMFC project.

I modified portapack’s firmware to enable the internal microphone and speaker by analyzing the datasheet of AK4951 sound chip, which is similar to Joop Brooking trying to use the MPU6050 for the flight controller program.