The Pocket SI4735 Dual Core Decoder project by H. J. Berndt continues to push the limits of what compact shortwave radios can achieve. Built around the proven SI4735 receiver chip and powered by an ESP32 dual-core processor, this miniature receiver combines exceptional sensitivity with intelligent digital decoding. The newest firmware update refines both performance and functionality, making this already capable “mini radio” even more powerful.
Designed for the Mini Radio Platform
Unlike generic firmware that only targets evaluation boards or large bench-top receivers, this firmware is specifically developed for the mini radio form-factor. It runs directly on the Pocket SI4735 Dual Core hardware already in use among enthusiasts — meaning that owners of these compact radios can apply the new update without hardware modification. It is fully compatible with existing units based on Berndt’s published design, ensuring that the firmware improvements translate directly into real-world performance gains.
The highlight of the new firmware is the introduction of an extended 400 kHz waterfall and scanner mode in both AM and SSB reception.
What’s New in the Latest Firmware
The highlight of the new firmware is the introduction of an extended 400 kHz waterfall and scanner mode in both AM and SSB reception. This wideband visual spectrum allows users to view a substantial portion of the radio band at once, similar to a small-scale SDR display. The result is a far better understanding of signal activity across a band and much faster tuning of stations.
In addition, SSB decoding has been improved for smoother and more stable voice reception, while RTTY and CW modes benefit from cleaner demodulation and more reliable decoding. The dual-core processor now handles signal processing and display updates more efficiently, leading to noticeably quicker response times and reduced lag when scanning, switching modes, or adjusting frequency.
The graphical interface has also been refined — the waterfall display now updates more fluidly, signal peaks appear sharper, and users can easily distinguish noise from real carriers. Collectively, these refinements transform the mini radio into a remarkably capable field receiver.
A Practical Upgrade for Mini Radio Owners
This firmware release is intended for the same class of mini radios already in the hands of many users. It is not an experimental build or a limited beta — it is the latest stable release that can be directly installed on existing Pocket SI4735 Dual Core Decoder hardware. For enthusiasts who already own one of these mini receivers, the update provides a tangible leap in capability: broader spectrum coverage, improved decoding, and faster visual feedback.
The latest firmware for the Pocket SI4735 Dual Core Decoder demonstrates how far the mini radio concept has evolved. By combining the SI4735’s analog-digital hybrid strengths with a dual-core ESP32 controller, and now enhancing it through advanced decoding and wideband scanning, H. J. Berndt has transformed a palm-sized device into a versatile listening instrument.
For existing users, this is not just an incremental improvement — it’s a full-scale upgrade that brings professional-grade monitoring features into the pocket-radio category.
You can read more details and download the latest firmware from the official project page:
👉 http://www.hjberndt.de/dvb/pocketSI4735DualCoreDecoder.html
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