What Problem Does It Solve?

The idea for this project came when E25VBE noticed how much airtime fellow Thai hams spent trying to describe signal quality and audio clarity. So instead of using vague or subjective audio reports, he built a tool that quantifies signal quality in real time—and makes it easy for everyone to understand.

How? By turning SNR (Signal-to-Noise Ratio) data into musical notes.

Yes, musical notes.

Signal Quality as Music

At the heart of this dashboard is a clever audio system: after each transmission, the SDR Monitor plugin reads signal strength from SDR# and plays a musical beep. Each note corresponds to a level of SNR—starting from Do-Re-Mi for S1 to S9, and beyond into +20, +40, +60 dB ranges.

This was not just an experiment. It worked—saving hams airtime and helping them focus on the real conversation.

However, some hams (especially those without musical training) had trouble identifying tone differences. So E25VBE took it further.

From Sound to Visual: Real-Time Graphs

He started publishing the same SNR data over MQTT and built an HTML-based dashboard to visualize the signal. What began as a sound-based tool quickly evolved into a powerful visual platform to analyze:

• SNR (dB) — How strong is your signal?
• Occupied Bandwidth — Is your modulation too wide or too narrow?
• Frequency Deviation — Is your rig on frequency or drifting off?

And the dashboard works in real-time, providing graphs every few seconds. Whether you’re using a basic setup or an advanced station, this tool allows you to fine-tune your audio, power output, frequency accuracy, and even antenna direction.

More Than Just Monitoring

The SDR Monitor Dashboard has become a full-blown diagnostic tool. Here’s what else it offers:

• GPS Location Logging – Pair your data with your station’s coordinates.
• Heatmap Mapping – See how far your signal travels and how strong it is across different areas.
• Antenna Rotation Visualization – Rotate your Yagi and watch the SNR graph paint your antenna’s radiation pattern.
• Field Test Comparison – Test different antennas (e.g., quarter-wave vs. NR22L) and compare results side by side.
• Contest Use – Six-month data retention allows verification of repeater QSOs during field day or contests.

Precision Calibration for All

One of the standout features is the ability to analyze modulation width and carrier frequency deviation. Many hams unknowingly over-modulate their rigs or shift slightly off frequency—this tool gives them the equivalent of a spectrum analyzer to self-calibrate.

It’s particularly helpful in group environments where overdeviation can cause adjacent channel interference and even friction among friends. This tool encourages proper operating practices.

Open Tools for the Community

Although not all components of the SDR Monitor are open source, E25VBE has shared many key elements publicly. For example:

DADA1 – Directional Antenna Deployment Assistant: An open-source web tool to calculate azimuth and distance between two ham stations using location names, Maidenhead grid locators, or lat/lon coordinates.

He’s also developed a user and installation manual, available in both Thai and English, and set up a demo site at http://dada1.decem.co.th to help hams calculate beam headings and rotation angles and dashboard here https://e24cy.decem.co.th.

Final Thoughts

This project is a fantastic example of how a passionate ham can take a real-world problem and turn it into a practical, technical, and user-friendly solution.

Whether you’re an everyday repeater user, a field-day operator, or just someone trying to fine-tune your antenna setup, the E24CY SDR Monitor Dashboard gives you the tools to do so with precision.

We highly recommend exploring the project if you’re interested in modernizing your repeater monitoring or signal analysis workflow. This is exactly the kind of innovation amateur radio needs right now.

More info and updates: Facebook Group

The post E25VBE SDR Monitor Dashboard: Making Signal Reports Smarter and Simpler appeared on Hamradio.my - Amateur Radio, Tech Insights and Product Reviews by 9M2PJU.

What is RMS and Why Does It Matter?

Before diving into the specifics of true RMS vs. non-true RMS, it’s important to understand what RMS means in the context of electrical measurements.

RMS stands for Root Mean Square—a statistical measurement of the magnitude of a varying signal. Unlike average readings, which only give you the average value of a waveform (which could be misleading for non-sinusoidal signals), RMS takes into account both the amplitude and the shape of the waveform. It’s essentially a way to quantify how much energy is delivered by a signal, whether it’s a pure sinusoidal waveform or something more complex like a square, triangle, or spiky waveform.

For purely sinusoidal signals, the RMS value is straightforward. However, when dealing with more complex waveforms, like those commonly found in RF signals or modulated carriers in the world of amateur radio, the RMS value can differ significantly from the average value. This is where true RMS measuring tools come into play.

True RMS vs. Non-True RMS: What’s the Difference?

Non-True RMS (Average Responding Meters):
Non-true RMS meters are designed to work well with sinusoidal waveforms but tend to give inaccurate readings when faced with anything other than a perfect sine wave. They typically use a diode or similar circuitry to average the signal, and then this average is multiplied by a constant to approximate the RMS value. For signals that are more complex, such as the square or pulsed waveforms frequently used in digital communication and modulation in amateur radio, these meters can give incorrect readings.

Non-true RMS meters generally measure the average value of a signal and assume that it is a sine wave. If you’re measuring a waveform that deviates from this ideal, you’ll get a reading that’s either too high or too low. This can lead to issues in accurately assessing power levels or troubleshooting equipment.

True RMS Meters:
True RMS meters, on the other hand, calculate the actual RMS value by integrating the signal across its entire waveform, regardless of shape. These meters use sophisticated circuitry to continuously sample the signal and compute the true RMS value, meaning that they can accurately measure both sinusoidal and non-sinusoidal waveforms. This makes true RMS meters indispensable for any serious amateur radio operator working with complex signals, especially when dealing with modulation schemes, noise, or distorted waveforms.

In short, true RMS meters give you an accurate representation of the power and energy being transmitted or received, regardless of the waveform shape, whereas non-true RMS meters are limited in accuracy to sine waves and can mislead when measuring complex signals.

Why Does This Matter for Amateur Radio?

Amateur radio operators often work with signals that are far from simple sine waves. Here are a few key reasons why true RMS meters are more important for your station:

1. RF Power Measurement:
   When measuring the RF power output from your transceiver, especially if it’s modulated with AM, SSB, or FM, the waveform is not a pure sine wave. A non-true RMS meter will misinterpret this and give inaccurate readings, potentially leading to a misunderstanding of how much power you’re really transmitting. A true RMS meter ensures that your measurements reflect the actual power output, helping you stay within legal limits and ensuring optimal performance.
2. Modulated Signals:
   Whether you’re transmitting in Single Sideband (SSB), Frequency Modulation (FM), or using digital modes like FT8, the waveforms are no longer pure sinusoids. These modulated signals involve varying amplitudes and frequencies, which non-true RMS meters can’t measure correctly. True RMS meters, however, handle these varying signals without issue, providing more accurate readings of your power levels.
3. Troubleshooting:
   When diagnosing issues with your equipment, non-true RMS meters can mislead you into thinking there’s a problem where there isn’t one. For example, if you’re testing a noisy signal or a modulated carrier, a non-true RMS meter might give you a strange reading that could cause you to misdiagnose the problem. Using a true RMS meter helps to rule out errors in measurement, allowing you to focus on real issues with your gear.
4. Signal Quality Analysis:
   Amateur radio often involves experimenting with different antenna setups, power levels, and modulation techniques. A true RMS meter is more useful when you’re testing the quality of signals transmitted or received over different conditions. Non-true RMS meters are prone to errors when trying to assess the effectiveness of new antennas, power amplifiers, or signal processing systems, especially when you’re working with irregular or highly modulated waveforms.
5. Standards and Calibration:
   For operators involved in contesting or those maintaining precise, calibrated stations, having a true RMS meter ensures that your measurements are as accurate as possible. Many radio standards for transmission power, signal strength, and harmonic distortion are based on RMS values, and using a true RMS meter helps ensure compliance with those standards.

Which Should You Choose?

True RMS meters are generally recommended for any amateur radio operator who wants to ensure the highest level of accuracy in their measurements. Though true RMS meters are often more expensive, the cost is justified if you’re serious about your setup and need precision in your power readings, signal analysis, and troubleshooting.

That said, non-true RMS meters can still be useful for simpler, everyday tasks, especially if you’re only measuring steady DC or clean sinusoidal AC signals. However, when it comes to complex RF signals, modulation schemes, or any situation involving varying waveforms, true RMS is the way to go.

Conclusion

In the world of amateur radio, precision and reliability are key. Whether you’re fine-tuning your transceiver, measuring your antenna system’s performance, or diagnosing signal issues, having the right tools can make all the difference. A true RMS meter will provide you with the accurate readings you need, regardless of waveform shape, while a non-true RMS meter may lead to inaccurate conclusions when faced with more complex signals.

Investing in a high-quality true RMS meter is a small price to pay for the peace of mind knowing that your measurements are as accurate as possible, helping you get the most out of your amateur radio experience.

The post True RMS vs Non-True RMS Measuring Tools: A Deep Dive into Accuracy for Amateur Radio Operators appeared on Hamradio.my - Amateur Radio, Tech Insights and Product Reviews by 9M2PJU.