Ats20 Firmware Best May 2026

The ATS20 firmware has become a cornerstone for radio enthusiasts looking to unlock the full potential of their SI4732-based all-band receivers. While these devices are affordable and compact, it is the community-driven firmware that transforms them from basic radios into versatile tools for DXing (long-distance listening).

In this article, we’ll dive into what makes the ATS20 firmware special, how it improves your hardware, and why the "v2" or "ATS20+" variants are the current gold standard. What is the ATS20 Receiver?

The ATS20 is a portable SI4732-based radio that typically covers FM, AM, and Shortwave (SW) bands. Out of the box, the factory firmware is often functional but limited—lacking fine-tuning controls, SSB (Single Side Band) stability, or a user-friendly interface.

The ATS20 firmware (often based on the open-source work of Ricardo Caratti and later modified by others) bridges this gap by utilizing the full processing power of the onboard Arduino/Atmega328p chip. Key Features of Enhanced ATS20 Firmware

Upgrading your firmware isn't just about bug fixes; it’s about adding professional-grade features to a budget device:

SSB (Single Side Band) Support: This is the "holy grail" for many users. Advanced firmware allows you to listen to amateur radio (HAM) operators, utility stations, and maritime communications by enabling LSB (Lower Side Band) and USB (Upper Side Band) modes. ats20 firmware

Fine Tuning Steps: Custom firmware often introduces variable tuning steps (1kHz, 5kHz, 10kHz, etc.), allowing you to zero in on a weak signal with precision.

Improved BFO (Beat Frequency Oscillator): This allows for better SSB demodulation, reducing "chipmunk voices" and making voice transmissions clear.

OLED Optimization: Many custom builds optimize the 0.96-inch OLED screen to show signal strength (S-meters), battery levels, and bandwidth settings more clearly.

Band Scanning: Some versions include a rudimentary scan feature to find active frequencies across the shortwave spectrum. The "ATS20+" and "v2" Evolution

If you are searching for firmware today, you’ll likely encounter the ATS20+ (v2). This version often features a larger battery, better filtering, and, crucially, firmware that supports a wider frequency range (sometimes down to 150kHz for Longwave). The ATS20 firmware has become a cornerstone for

The firmware for the ATS20+ is specifically tuned to handle the slightly different hardware layout and rotary encoder behavior found in the updated models. How to Update Your ATS20 Firmware

Most ATS20 radios use an Arduino-compatible microcontroller. To update:

Hardware Connection: Connect the radio to your PC via a USB cable (ensure your radio has a USB-to-serial chip like the CH340). The Software: Use the Arduino IDE or XLoader.

The Code: Download the .ino or .hex file from a reputable source like GitHub (search for "SI4735-Arduino-Library-master" by PU2CLR).

Flash: Select the correct COM port and board (usually "Arduino Nano") and hit upload. Why Enthusiasts Love It Touch Key Sensitivity: Many users complain that the

The ATS20 firmware community is highly active. Users frequently share modified versions that change the UI colors (if using a compatible screen), add "favorite" station memories, or improve the AGC (Automatic Gain Control) for better performance during high-interference periods. Conclusion

The ATS20 firmware is more than just code—it’s the "soul" of the radio. By moving away from the stock software, you turn a $40 gadget into a surprisingly capable receiver that rivals much more expensive units in the amateur radio world.

5. Known Firmware Limitations

• Touch Key Sensitivity: Many users complain that the firmware's handling of the capacitive touch keys is either too sensitive or not sensitive enough (often requiring calibration).
• SSB "clicks": Some older firmware versions produced audible "clicks" when tuning SSB frequencies.
• Sync Detection: Unlike the ATS-25 (a successor model), the ATS-20 firmware generally lacks synchronous AM detection, which can make shortwave listening prone to fading distortion.

Version 1: The "Original" ATS-20

• Pros: Stable, simple interface.
• Cons: SSB support was initially buggy; BFO control was difficult to use in early versions.

4. The Spectrum Waterfall (ATS20+ Only)

The most exciting feature added by firmware like PU2CLR's SSB library is a rudimentary spectrum scope. Using the radio’s internal ADC, the screen can display a live waterfall of signals up/down the band.

Part 7: Beyond Firmware – Hardware Mods

Once you have mastered the firmware, consider pairing it with hardware mods for professional performance:

1. The BFO Clarifier: Add a small trimmer potentiometer to the Si4732's REFCLK pin for analog fine-tuning of SSB (bypassing the software PPM).
2. Frontend Filtering: Install a band-stop filter for FM broadcast (88-108 MHz) to prevent intermodulation distortion on shortwave.
3. External Antenna: Firmware is useless without signal. Use a 30-foot wire with a 9:1 unun into the SMA port.

Why Replace the Stock Firmware?

Out of the box, the ATS-20 works well for basic AM/SSB listening. But many users encounter limitations:

• Limited Bandwidth Options: The stock filters can be too wide for crowded CW (Morse code) bands.
• Clunky User Interface: Tuning and memory management can feel slow.
• Missing Features: No spectrum waterfall, limited noise reduction, or lack of support for external hardware.

Custom firmware solves these problems by rewriting the control logic of the Si4732 chip.