PhaseLatch Mini is a compact, low-cost direct-conversion SDR frontend built around the popular STM32F103 “Blue Pill” microcontroller. Designed to pair seamlessly with the PhaseLoom IQ mixer—or any other quadrature front-end—it provides true simultaneous I/Q sampling using the MCU’s dual ADCs and streams raw baseband data over USB for easy integration with GQRX, GNURadio, or custom DSP tools.
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Unlike typical microcontrollers that multiplex multiple inputs into a single ADC, the STM32F103 offers two fully independent ADCs running in lockstep. This allows PhaseLatch Mini to capture clean, time-aligned I/Q data without expensive hardware or specialized chips. A carefully tuned passive low-pass filter provides anti-aliasing, while DMA ensures continuous, uninterrupted streaming at over 200 kHz of usable bandwidth.
Perfect for radio experimenters, hobbyists, and developers working with HF and FM broadcast signals, the PhaseLatch Mini is ideal for learning about SDR architecture, IQ imbalance, mirror rejection, digital downconversion, and the challenges of real-world RF.
The entire project—including firmware, schematics, and Python host scripts—is fully open source. You can explore, modify, and build your own version directly from the GitHub repository:
Whether you're exploring ham radio, building custom receivers, or extending your retrocomputing SDR setup, PhaseLatch Mini is a powerful, affordable tool for modern RF experimentation.