Talking SWR Meter LX1WJ

Accessible talking SWR + RF power meter for blind & visually impaired amateur radio operators.

What it is

A standalone SWR/power meter based on an ESP32-S3 and an RF directional coupler (FWD/REV DC outputs).
All key information is provided via speech and Morse, so no display is required.

Project Philosophy & Status

This project is not for commercial sale. Its purpose is to empower the amateur radio community to build and donate accessible controllers for blind or visually impaired operators under the open-source model.

Key features (overview)

• Firmware version 5.5
• Speech output via I2S audio amplifier (e.g. MAX98357A) + speaker
• Morse output via buzzer
• Tuning mode: continuous SWR with audio pitch feedback (tracks minima)
• 6-button user interface using a resistor ladder on one ADC pin
• Built-in web UI (ESP32 Wi-Fi AP) for status, settings, and calibration
• mDNS hostname: swrmeter.local (if supported by client)
• Settings + calibration stored persistently (NVS)
• Extended calibration table with 66 measurement rows
• Calibration page with per-row Measure and Clear buttons
• Calibration export/import as JSON and CSV

Disclaimer / Safety Notice

This project is provided for experimental and educational use only, AS IS, without any warranty.

• The device is not a certified measuring instrument.
• Measurements may be inaccurate and can lead to equipment damage or unsafe RF operation if relied upon.
• You are responsible for correct wiring, safe RF practices, and compliance with local regulations.
• Always verify results with trusted instruments (e.g. wattmeter/dummy load) before relying on them.

Use at your own risk.

Hardware required (minimum)

• ESP32-S3 development board
• RF directional coupler / SWR bridge (50 ohm) with DC outputs: FWD and REV (keep within 0...3.3 V at ADC)
• I2S audio amplifier + speaker
• Piezo buzzer (PWM)
• 6 pushbuttons + resistor ladder (single ADC input)
• 12 V supply (and regulators as needed)

Quick start

1. Flash firmware src/Talking_SWRMeter_LX1WJ.ino to the ESP32-S3 with voice_data.h.
2. Power on: the device starts a Wi-Fi access point named SWR-Meter-S3-FW 5.5.
3. Connect with phone or PC and open: http://192.168.4.1/
4. Use T1/T2 for Morse or speech measurement.
5. Calibrate your coupler in the web UI. In V5.5 you can capture Ufwd/Uref directly per row with the Measure button.
6. Save calibration and optionally export it as JSON or CSV.

Documentation

• Detailed operating guide: USAGE.md
• Calibration quick guide: docs/Quick guide for calibration V5_5.txt
• Bill of materials: docs/bom-V5_5.txt
• Principle and wiring overview: docs/talking-swr-meter-principle-V5_5.txt
• Additional reference material: docs/

License

Firmware source code: GPL-3.0
Documentation: CC BY-SA 4.0
See LICENSE and LICENSE-docs.