Kodera2t's Arduino-Compatible DSP Radio v5 Adds Single Sideband Support for FT8 Ham Radio Reception

Radio enthusiast kodera2t has updated their homebrew DSP Radio project, launching a new v5 entry in the board family which includes single sideband (SSB) reception.

"Very recently I took an amateur radio license and got to know digital mode communication (FT8) becomes very popular," writes kodera2t of the inspiration behind the fifth entry in their radio family. "FT8 signal is modulated by SSB (single sideband) with USB (upper sideband) and it cannot be demodulated by general shortwave receiver including my other item (DSP radio version 4). In addition, I love CW (Morse code) communication, but also it cannot be demodulated by general (broadcast) shortwave receiver.

"I know, USB dongle type SDR can easily realise super wide-band reception with multi-mode demodulation including SSB, but it requires 'base' PC. I just wanted to make a 'handy and independent shortwave SSB receiver.' On the other hand, very recently some people released 'special code' enabling SSB reception by Si4735, and also established a very useful library. After knowing this fact, it did not take more than one week for starting my new SSB receiver project."

The new design is based on the Silicon Labs Si4735, which covers the high frequency (HF) amateur bands from 1.9MHz to 28MHz. A compact OLED display is provided for feedback, while control is handled by an ATmega328P flashed with the Arduino Pro bootloader — making it fully compatible with the Arduino IDE without requiring external board definitions. The design also includes a built-in lithium-polymer battery charging circuit, six tactile switches, a rotary encoder for tuning, and a CP2102N USB UART.

The firmware for the DSP Radio v5 is now available on kodera2t's GitHub repository; a Tindie store listing prices the boards themselves at $62 each fully-assembled, but is currently out of stock pending the delivery of additional OLED panels.