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. Check out the video in this update for more information.