UUGear’s VU GPSDR is an affordable GPS-disciplined SDR expansion board tailored for the Vivid Unit, a compact Rockchip RK3399-based touchscreen SBC introduced in 2024. The VU GPSDR utilizes the RTL2832U ADC and Rafael Micro R860 tuner, distinguishing itself from SDRs like the PhaseLatch Mini and DeepRad SDR by integrating a u-blox NEO-M8N GPS module. This module provides a GPS-disciplined 24 MHz clock reference to the Si5351 local oscillator, ensuring high frequency stability and timing accuracy found in more expensive SDR hardware.
VU GPSDR Specifications:
– Supported Platform: UUGear Vivid Unit through Vivid Unit Extender Gen 1/2
– MCU: STM8S003F for board-level controls
– RF:
– Tuner: Rafael Micro R860
– ADC: Realtek RTL2832U
– Frequency Range: 500 kHz to 1.766 GHz
– Bandwidth: Up to 3.2 MHz (2.4 MHz recommended for stability)
– HF Support: Integrated 108 MHz up-converter for sub-30 MHz reception (Shortwave/Amateur bands)
– Antenna:
– 1x SMA (SDR input); no Bias-Tee
– 1x SMA Output (Software-controlled clock source via Si5351)
– Clocking:
– Local Oscillator: Si5351, disciplined by 24 MHz PPS from u-blox NEO-M8N GPS
– GPS-adjusted clock for long-term frequency accuracy; reverts to internal TCXO without GPS fix
– 1x onboard GPS antenna connected via IPEX 1st gen connector; with 5V Bias-Tee support
– I2C header for NEO-M8N
– Misc:
– Dual rotary encoders (software-configurable for tuning, volume, zoom, etc.)
– 2x push buttons for controls
– GPS fix green LED
– SWD header for STM8 MCU
– Dimensions: 210 × 110 × 10 mm
– Weight: 0.065 kg
To utilize the SDR board, the Vivid Unit Extender is required, connecting to the back of the Vivid Unit via GPIOs and three other connectors, and the VU GPSDR board connects via the Vivid Unit Extender’s mini PCIe connector. The VU GPSDR supports both the Vivid Unit Extender gen 1 and gen 2, with Gen 2 offering a CH224K fast-charging controller, a quieter 4-wire blower-type fan for improved thermals, additional screw terminals for external power supply, over/undervoltage protection, RTC, and a watchdog.
The VU GPSDR operates with GPSDR++, a fork of the open-source SDR++ (v1.2.0) project. For handling real-time waterfall displays and demodulation on the Vivid Unit’s RK3399 SoC, enabling GPU acceleration for the Mali-T860 GPU is recommended to prevent lag. Installation for the Vue package and the gpsdrpp binary is straightforward via apt on the Vivid Unit’s Debian-based OS.
The VU GPSDR expansion board is available for €65.00 (approx. $77.40 USD) on the UUGear E-Shop. However, it is not a standalone device; the Vivid Unit (€99.00) and the Vivid Unit Extender (€28.00) are also required. The total cost for a complete handheld system is roughly €192 (approx. $205 USD), excluding antennas.