If you hold a license and you like to build, here are 15 concrete possibilities for the Cardputer-Adv in amateur radio. All of them are technically feasible based on the hardware. None require you to suspend disbelief.

1. Your Shirt-Pocket APRS Terminal

The Cardputer-Adv has the 3 essentials for APRS: a keyboard to type messages, a 3.5mm jack for AFSK audio, and a 1750mAh battery that lasts a field day. Flash TNC firmware and you’ve got a self-contained tracker. No phone, no Mobilinkd, no cable mess. Type >APRS and send a message from a summit.

2. FT8 Without the Laptop

The ESP32-S3 can decode FT8. Several projects already prove it. The Cardputer adds a screen and keyboard to the equation. The possibility: walk to a park, plug into your QDX or IC-705, and work FT8 while the sun is up. The 1.14″ screen is tight, but you only need to see the callsign and report.

3. A Real CAT Control Head for Portable

Tired of digging through radio menus? The EXT header gives you UART and I2C. That means the Cardputer could become a dedicated CAT panel. Map the 56 keys to band, mode, VFO A/B, or CW memories. For rigs like the FX-4CR or uSDX, this is a lighter alternative to a laptop.

4. The Satellite Pass Assistant You Actually Carry

Satellite work is all about timing and pointing. The Cardputer-Adv can pull TLEs over WiFi, calculate the next pass, and show AZ/EL. Strap it to your Arrow antenna and the BMI270 IMU turns it into a digital compass. You get live pointing data on screen while you work RS-44.

5. Rotator Controller for Your SOTA Beam

Doing SOTA with a small Yagi? Use the Cardputer’s GPIO to drive a light rotator. The IMU gives you heading feedback so you know where the beam is pointing. No more guessing or using your phone’s compass next to metal.

6. Morse Code Swiss Army Knife

CW ops get a lot here. The audio in means it could decode incoming Morse. The keyboard means it becomes a memory keyer. The speaker means instant code practice. For Field Day, it’s a logger, keyer, and decoder in 81 grams.

7. SWR Meter With a Brain

Connect a basic directional coupler to the ADC pins. Now the Cardputer-Adv can display SWR, power, and plot graphs. Save sweeps to the microSD. You’ve just built an antenna analyzer display that runs all day on its internal battery.

8. QRP WSPR Beacon

The ESP32-S3 is stable enough for WSPR timing. Add a simple LPF and you have a beacon that runs for 24+ hours. Use the keyboard to set your callsign and grid. Hang a wire in a tree and spot yourself on WSPRnet.

9. Echolink/AllStar DTMF Pad

The ES8311 codec generates clean tones. The possibility: use the Cardputer as a dedicated DTMF pad for Echolink, IRLP, or your club repeater’s autopatch. No more fighting with your phone’s dialer.

10. The MMDVM Hotspot Display We Needed

Hotspots are tiny and headless. The Cardputer-Adv could connect over serial and show talkgroup, last heard, BER, and CPU temp. Map keys to “Parrot”, “Disconnect”, or “TG4000”. Your hotspot finally gets a front panel.

11. Contest & SOTA Logger That Fits in Your Palm

Typing on a phone in the rain is misery. The 56-key board is tactile. Log callsign, RST, and exchange straight to microSD in ADIF. Import to N1MM later. The battery won’t die in the middle of a pileup.

12. SSTV on a Keychain

Decode SSTV from the audio jack and see the picture right there on the 1.14″ screen. It’s small, but for Robot 36 from the ISS, it works. You can also generate SSTV audio to send your own images QRP.

13. Fox Hunt and RFI Hunting Tool

Feed signal strength from an HT into the ADC. Combine it with the IMU heading and you’ve got a digital fox hunt display. It could log bearings and triangulate. For RFI hunting, log signal vs. position as you walk.

14. Wireless Remote Head for the Shack

Running a Flex or IC-705 at home? The Cardputer-Adv has WiFi and BT. It could become a wireless control head. Sit in the backyard and run your base station from the patio using your home network.

15. APRS iGate in a Box

Combine the TNC function with WiFi. The Cardputer could hear packets on RF and gate them to APRS-IS. Solar + battery + Cardputer + UV-K5 = ultra-portable iGate for events or emergencies.

The Reality Check

To be clear: none of this works out of the box. The Cardputer-Adv ships as a blank ESP32-S3 board. You need firmware, cables, and a real radio. It won’t replace your FT5DR or IC-7300.

But if you’re the kind of ham who owns a soldering iron and has compiled Arduino code before, the possibilities are real. You’re looking at $50 of hardware that can replace 4 separate gadgets in your go-kit.

The post The M5Stack Cardputer-Adv and Amateur Radio: 15 Real Possibilities Worth Exploring appeared on Hamradio.my - Amateur Radio, Tech Insights and Product Reviews by 9M2PJU.

For years, if you wanted to set up a serious APRS (Automatic Packet Reporting System) node—be it an iGate, a Digipeater, or a Tracker—you usually had two choices. You could buy an expensive, proprietary TNC (Terminal Node Controller), or you could wrestle with a soundcard modem and a dedicated PC.

But the game has changed.

Today, we are diving deep into a project that is making waves in the community, developed by Thai amateur radio operator Somkiat Nakhonthai (HS5TQA). It is called ESP32APRS_Audio, and it might just be the most versatile, cost-effective APRS solution available today.

What is ESP32APRS_Audio?

At its core, ESP32APRS_Audio is a firmware that turns a standard ESP32 microcontroller into a fully functional Software TNC.

Unlike other ESP32 projects that require specific LoRa modules or complex digital interfaces, this project utilizes the ESP32’s internal DAC (Digital to Analog Converter) and ADC (Analog to Digital Converter) to generate AFSK (Audio Frequency Shift Keying) tones directly.

In plain English: You can plug this $5 chip directly into the microphone and speaker jack of any analog radio—from a Baofeng UV-5R to a 25-year-old Yaesu mobile—and turn it into a modern, internet-connected APRS station.

Why This Project is a Game Changer

1. It’s a True “Soft-Modem”

Most modern APRS projects rely on external hardware modems. HS5TQA’s code implements the modem entirely in software.

• VHF: Standard 1200bps AFSK (Bell 202) for 2m operations.
• HF: 300bps AFSK (Bell 103) for long-range HF packet.
• UHF High Speed: 9600bps GFSK (supported on ESP32-S3).

2. The “Swiss Army Knife” of Modes

One firmware flash gives you every mode you could possibly need. You don’t need different code for different jobs; you just change the settings in the web interface.

• iGate (Internet Gateway): Listens to RF traffic and pipes it to the APRS-IS internet servers via WiFi.
• Digipeater: Listens for packets and re-transmits them to extend network range.
• Tracker: Connects to a GPS and beacons your location.
• Weather Station: Interfaces with weather sensors to report telemetry.

3. FX.25 Support

This is a huge technical win. The firmware supports FX.25, which is an upgrade to the standard AX.25 protocol. It wraps the standard packet in “Forward Error Correction” (FEC) data.

• The Benefit: If a packet gets slightly corrupted by static, FX.25 can mathematically repair it.
• Compatibility: It is fully backward compatible. Standard TNCs will just see a normal packet, but FX.25-enabled stations (like Direwolf or this ESP32) will enjoy much better decoding in noisy environments.

The Hardware: Simplicity Itself

You don’t need a degree in electrical engineering to build the interface. The repository provides the schematic for the ESP32DR Simple Circuit.

To connect the ESP32 to a radio, you essentially need three things:

1. Isolation: A simple 600:600 Ohm audio transformer prevents ground loops (hum) between your radio power and ESP32 power.
2. Level Adjustment: A voltage divider (potentiometer) to drop the radio’s loud speaker audio down to the 3.3V range the ESP32 can handle.
3. PTT Control: A simple NPN transistor (like a 2N3904) to trigger the Push-To-Talk on the radio.

Supported Boards:

• Standard ESP32 (DevKit V1)
• ESP32-C3
• ESP32-S3

The Software Experience: No Coding Required

One of the biggest barriers to entry for Ham projects is the “Compile Error.” You download a project, try to upload it, and spend 4 hours debugging library conflicts.

ESP32APRS_Audio solves this by focusing on a Web-Based User Interface.

1. Flash Once: You use the Espressif download tool to flash the binary files one time.
2. Config via WiFi: The ESP32 creates a WiFi Hotspot (ESP32APRS_Audio). You connect to it with your phone or laptop.
3. Browser Control: You navigate to 192.168.4.1 and are greeted with a full dashboard. You can set your Callsign, SSID, Latitude/Longitude, Digipeat paths, and Volume levels visually.

Advanced Features for the Power User

For those who want to push the envelope, HS5TQA has packed in enterprise-level features:

• VPN (WireGuard): Secure your connection if you are placing this on a remote mountain top.
• MQTT: Integrate your radio data into Home Assistant or other IoT dashboards.
• Bluetooth TNC: It enables the Bluetooth SPP (Serial Port Profile). You can pair your Android phone running APRSdroid to the ESP32, using it as a wireless TNC for your mobile operations.

How to Get Started

1. Visit the Repo: Go to GitHub – nakhonthai/ESP32APRS_Audio.
2. Order the BOM: An ESP32 DevKit, a few resistors, capacitors, and an RJ11 or TRRS jack for your radio.
3. Build the Cable: Follow the “ESP32DR Simple” schematic.
4. Flash & Deploy: Get your station on the air for under $20 USD.

Conclusion

The ESP32APRS_Audio project is a testament to the spirit of amateur radio. It takes accessible, inexpensive modern technology and bridges it with the legacy RF hardware we all love. Whether you are looking to fill a coverage gap in your area with a cheap Digipeater or build the ultimate mobile tracker, this project deserves a spot on your workbench.

https://github.com/nakhonthai/ESP32APRS_Audio

The post The Ultimate “DIY APRS TNC”: A Deep Dive into the ESP32APRS Audio Project appeared on Hamradio.my - Amateur Radio, Tech Insights and Product Reviews by 9M2PJU.

If you’re passionate about amateur radio and embedded systems, you might want to check out HFTRX, an advanced SDR transceiver project hosted on GitHub by ua1arn. Designed with serious radio operators in mind, HFTRX stands out for its deep integration of SDR (Software Defined Radio) technology, open-source firmware, and support for a wide range of hardware platforms—from STM32 and Cortex-A series to Zynq and even Allwinner SoCs.

But this isn’t just another software project. It’s the backbone of a high-performance HF transceiver called Storch (Аист), aimed at covering the entire 30 kHz to 54 MHz band with robust transmit power and excellent receive sensitivity. With extensive documentation, build instructions, and community support, the HFTRX project is accessible for DIYers, radio builders, and embedded developers alike.

Key Features of the “Storch” Transceiver

The HFTRX-based Storch is no toy—it’s a serious rig capable of:

• Wide Frequency Coverage:
  • Receive: 30 kHz to 54 MHz
  • Transmit: 500 kHz to 54 MHz
• High Power Output:
  • 100W typical from 1 MHz to 40 MHz (200W with tuned antenna)
  • 10W below 1 MHz, and 20–35W above 40 MHz
• 16-bit ADC @ 122.88 MHz, delivering high dynamic range (≥125 dB)
• 24-bit audio for crystal-clear sound quality
• Multi-band reception across sub-bands simultaneously

Built for Performance

What makes the HFTRX design unique is its direct digital conversion (DDC) architecture, which eliminates many analog stages and offers superior performance with fewer components. This not only simplifies design but also boosts stability and scalability.

Some standout components of the design include:

• Built-in antenna switcher (2 TX/RX + 1 RX)
• Automatic antenna tuner (ATU) with memory presets
• IQ output for external signal processing
• Remote access via Ethernet
• USB recording and control
• Adaptive cooling system with low noise levels
• Robust protection circuits against overheating, ESD, and polarity reversal

Developer & Maker Friendly

HFTRX isn’t just plug-and-play—it’s also developer-friendly with source code and hardware documentation readily available. Whether you’re a hardware hacker, firmware tinkerer, or FPGA enthusiast, you’ll find valuable resources like:

• Full Gerber files and schematics
• Detailed BOM (Bill of Materials)
• Assembly and tuning manuals
• Support for Eclipse and CMSIS-based IDEs
• FPGA projects in VHDL and Verilog
• Modular structure across STM32, Zynq, and Allwinner targets

Developers can jump right in with setup instructions and an active development branch, while radio builders can dive into the assembly and tuning docs to bring their own Storch to life.

Community Support & Collaboration

The project is spearheaded by Gennadiy Zavidovskiy (UA1ARN) and features contributions from a small but passionate group of developers and amateur radio operators. Communication channels are available through Telegram:

• Chat: Sokol_SDR_DDC
• Channel: sokol_ddc

This open collaboration approach makes it easy to ask questions, share builds, and contribute code.

Ideal for Experimenters, Hackers, and Operators

If you’ve been looking for a modern, DIY-friendly SDR project that doesn’t skimp on features or performance, HFTRX is a solid contender. Whether you want a powerful HF transceiver, a flexible SDR platform, or just a way to dive deeper into embedded development for radio systems, this project has something to offer.

With the added flexibility of external VHF transverter support (e.g. 144–146 MHz), Ethernet and USB interfaces, and high-quality digital audio paths, this project is a future-proof entry into the world of homebrew high-performance rigs.

Get Started

You can explore the project, download the code, and access all documentation here:
https://github.com/ua1arn/hftrx

The post Exploring the HFTRX SDR Transceiver: A Powerful Open-Source Project for Ham Radio Enthusiasts appeared on Hamradio.my - Amateur Radio, Tech Insights and Product Reviews by 9M2PJU.