NNJ-SDR++: Improved Firmware and Software for Kintex-7 AD9361 B210 Clones

USRP B210 Chinese clones can now be commonly found on marketplace sites for less than USD$300. This is a bargain, considering that an original USRP B210 (board only) costs US$2,387. The disadvantage is, of course, janky ported firmware that doesn't support all the available features and doesn't maximize the available performance.

Recently, Fabrizio Francione wrote in and wanted to share his new firmware and software project, called "NNJ-SDR++ UHD Edition V1.0". This project consists of improved firmware that unlocks the full sample rate, fixes various problems, and enables the onboard GNSS receiver. It also includes a modified SDR++ frontend that exposes more controls. Fabrizio writes:

The work involved substantial FPGA and software development rather than simply customizing the SDR++ interface. Starting from the original B210-compatible architecture, I progressively redesigned and extended several areas of the firmware, including improved CIC numerical handling, RX/TX fixed-point processing, BRAM-based asynchronous transport FIFOs, CIC passband compensation, a wideband FIR receive path, ADC clipping/overload telemetry, runtime FPGA control and diagnostics, and a dedicated wideband profile for operation at up to 56 MS/s.

I also finally integrated the board's onboard u-blox MAX-M10S GNSS receiver directly with the FPGA, including GPS UART data, internal PPS capture and timing telemetry, while preserving external 10 MHz reference and PPS support.

On the host side, I developed a customized UHD 4.10 environment and SDR++ frontend for both Windows and Linux. The application exposes RF filter bandwidth, LO offset, reference lock, PPS status, GNSS information, firmware telemetry and other board-specific controls directly from the SDR++ source panel.

One particularly interesting part of the project was making sustained 56 MS/s operation practical across both operating systems while retaining B210/UHD compatibility.

The Firmware is not open source or free, and Fabrizio is selling it for US$19.90.