uSDR was designed as a compact M.2 software-defined radio for embedded systems, browser-based SDR workflows, and practical RF experimentation.
One important capability added to the platform is receive support for HF and VHF bands.
This expands uSDR's usefulness beyond higher-frequency SDR applications and makes it relevant for amateur radio, FM broadcast reception, low-frequency RF experiments, education, and general spectrum exploration.
| Path | Frequency Range | Typical Use |
|---|---|---|
| HF/VHF up-converter | ~1 MHz – 300 MHz | Amateur radio, FM broadcast, low-band experiments |
| Main RF input | up to 3.8 GHz | General SDR, cellular, ISM-band research |
Extending receive coverage
To support HF and VHF reception, uSDR uses an up-converter architecture. Lower-frequency signals are translated upward into a range that can be processed by the main SDR signal chain.
This approach allows uSDR to receive signals in approximately the 1 MHz to 300 MHz range while keeping the board compact and compatible with its existing architecture.
The receive extension is useful for:
- HF reception
- VHF reception
- amateur radio monitoring
- FM broadcast reception
- low-frequency RF experiments
- education and lab demos
- spectrum exploration
Up-converter architecture
The HF/VHF receive path uses a mixer-based up-conversion approach. In this architecture, lower-frequency input signals are mixed with a local oscillator, shifting them into a range suitable for the SDR receive chain.
This allows the compact M.2 board to support lower-frequency reception without requiring a much larger analog front end.
Additional filtering helps reduce unwanted mirror images and harmonic content.
Dedicated HF/VHF antenna path
Lower-frequency signals typically require different antennas than higher-frequency SDR operation. For this reason, uSDR includes a dedicated antenna path for HF/VHF reception.
This gives users a practical way to connect antennas suitable for lower-frequency bands without compromising the main RF path.
Native and web interface support
HF/VHF receive support is available through native SDR workflows and through the web interface.
This means users can explore lower-frequency bands using tools such as GQRX and other native applications, or through Wavelet Lab's browser-based WebSDR environment.
That dual-mode support is important because different users work in different ways:
- hobbyists may prefer GQRX or familiar SDR tools
- developers may prefer native APIs
- educators may prefer WebSDR for browser-based demonstrations
- researchers may use both native and browser-based workflows
Why this matters
Many compact SDR platforms focus on higher-frequency applications and require external hardware for HF/VHF reception.
Adding HF/VHF receive capability makes uSDR more versatile. It allows one compact platform to support a wider set of use cases, from browser-based signal visualization to traditional radio-band exploration.
For users who want a small SDR module that can support both embedded workflows and general RF experimentation, this capability makes uSDR more flexible.