Project
Talking SWR Meter
This private site collects amateur radio, accessibility-related electronics projects. The Talking SWR Meter is an accessible SWR and RF power meter with spoken output.
It helps blind and visually impaired amateur radio operators check antenna matching and RF power without depending on a display. The device speaks the important values aloud and can also give Morse or audio feedback while tuning.
Meet The Talking SWR Meter
When a transmitter sends power to an antenna, not all antennas are matched equally well. A good match sends most of the power into the antenna. A poor match reflects power back toward the radio. The Talking SWR Meter measures forward and reflected power through an RF directional coupler and turns that into useful spoken information.
In everyday use, the operator can press a button and hear values such as SWR, forward power, reflected power or tuning feedback. The project is built around an ESP32-S3, speech output, a small speaker, a buzzer for Morse feedback and a simple six-button user interface.
Spoken Measurements
The meter reads important antenna and power information aloud.
No Display Required
The core operating idea is usable audio feedback instead of visual-only readings.
Tuning Feedback
A tuning mode can provide continuous audio pitch feedback while looking for a better match.
Web Settings
The built-in Wi-Fi web UI is used for status, settings and calibration.
What It Measures
The meter is designed for the common amateur radio task of checking whether the radio, feed line and antenna are working together safely and efficiently.
| Value | What it means | Why it helps |
|---|---|---|
| SWR | How well the antenna system is matched to the radio. | A lower SWR usually means less reflected power and a safer match. |
| Forward power | The RF power going from the transmitter toward the antenna. | It confirms that the transmitter is producing power. |
| Reflected power | The RF power coming back from the antenna system. | It warns when too much energy is being reflected back. |
| Tuning trend | Audio feedback while adjusting an antenna tuner or antenna setup. | It helps find the better match without watching a meter needle or screen. |
Example Use
Check Before Transmitting
- Connect the meter between the transmitter and antenna system.
- Use low power first.
- Press the measurement button.
- Listen to the spoken SWR and power values.
Tune An Antenna
- Start tuning mode.
- Transmit a low-power carrier suitable for tuning.
- Adjust the tuner or antenna while listening to the audio feedback.
- Stop when the feedback indicates the best match you can achieve.
Use The Web UI
- Power on the ESP32-S3 device.
- Connect a phone or computer to its Wi-Fi access point.
- Open http://192.168.4.1/.
- Use the web page for status, settings and calibration.
Calibrate The Coupler
- Use a trusted wattmeter and dummy load as a reference.
- Calibrate the forward and reflected readings in the web UI.
- Export or import calibration data as JSON when needed.
- Recheck the setup before trusting watt readings.
Basic Hardware Idea
The minimum build uses an ESP32-S3 development board, a 50 ohm RF directional coupler or SWR bridge with forward and reflected DC outputs, an I2S audio amplifier and speaker, a piezo buzzer, six pushbuttons through a resistor ladder and a suitable power supply.
The coupler outputs must stay within the ESP32-S3 ADC input range. Calibration is required before watt readings are meaningful.
This is an experimental and educational open-source project, not a certified measuring instrument. Always verify results with trusted instruments and follow safe RF practice.