THD Sweep Measurement

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THD SWEEP MEASUREMENT - USER GUIDE

Master the art of measuring Total Harmonic Distortion with style

🎵 THD SWEEP MEASUREMENT
Professional Acoustic Testing Made Simple

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⚡ QUICK START - 30 SECONDS

STEP ACTION
1️⃣ Launch Double-click Lancer_THD.bat
2️⃣ Connect Check top right: ● Connected
3️⃣ Start Click green ▶ START button
4️⃣ Monitor Watch 4 metrics update live
5️⃣ Stop Click red ■ STOP button

✅ That's it! Your first THD measurement is complete. You're now a certified acoustic engineer. (Not really, but it feels good.)

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👀 YOUR INTERFACE - WHAT YOU SEE

🟢 Status Indicators (Top Right)

INDICATOR MEANING
● NVGate Connected Perfect! NVGate is ready to rock 🎸
● NVGate Disconnected Oops! Start NVGate first 🤔
● Measurement Running Data is flowing! 📊
● Measurement Stopped Ready for the next round ⏸️

📊 Four Metric Cards

The heart of the interface. These four numbers tell the whole story:

📈
THD (dB) 		📊
THD (%) 		📡
Frequency 		⚡
Fundamental
Harmonic distortion (log scale) Harmonic distortion (%) Current sweep point Signal strength
+5.42 dB 58.294 % 1234.56 Hz 5.0e-01 V

💬 Log Console (Bottom)

Real-time messages with color coding:

🟢 GREEN Everything OK - measurement working perfectly
🔴 RED Error occurred - something needs attention
🔵 BLUE Information - status updates and details

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🎯 UNDERSTANDING YOUR RESULTS

THD (%) - The Easy Number

What is it? Percentage of unwanted harmonics in your signal.

Think of it this way:

  • THD 5% = 95% pure signal, 5% noise
  • THD 20% = 80% pure signal, 20% noise

The Quality Scale:

🌟 1% - 5% Excellent - Professional grade equipment
✅ 5% - 15% Good - Solid speaker performance
⚠️ 15% - 30% Acceptable - Consumer level equipment
❌ > 30% Poor - Time for an upgrade 🛠️

THD (dB) - The Technical Number

Same measurement as THD (%) but in decibels (logarithmic scale).

Quick Conversion Chart:

THD % THD dB Quality
1% -40 dB 🌟 Perfect
3% -30 dB ✅ Great
10% -20 dB ✅ Good
30% -10 dB ⚠️ Poor

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📋 TYPICAL MEASUREMENT WORKFLOW

Pre-Measurement Checklist

Before you start, verify:

  • ✓ NVGate is open and ready
  • ✓ Sweep is configured (e.g., 10 Hz → 20 kHz)
  • ✓ FFT traces are visible on screen
  • ✓ Sine generator is active
  • ✓ Speaker is connected and working

Step-by-Step Workflow

PHASE WHAT TO DO
1️⃣ Prepare Open NVGate → Set sweep → Verify FFT visible
2️⃣ Launch App Double-click Lancer_THD.bat → Check Connected status
3️⃣ Start Click ▶ START → Watch log for "Starting THD Measurement"
4️⃣ Monitor Watch metrics update → Frequency should increase → THD should be stable
5️⃣ Stop Click ■ STOP → Watch for "Measurement ended" → Note final values

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⚙️ CONFIGURATION

When Do I Need to Change This?

Honest answer: Almost never.

The default settings work for 95% of users. Only change if your NVGate project has:

  • Different window names
  • Different marker numbers
  • Different DC input addresses

If you're not sure → Don't change anything. It works. Trust it.

How to Access Configuration

Click on ▶ Configuration (section expands)

Important Settings

Setting Default When to Change
Window (sweep) Window2 Your sweep FFT has different name
Window (response) Window1 Your response FFT has different name
Number of harmonics 9 5 (faster), 15 (more detailed)

How to Apply Changes

  1. Modify field value
  2. Click Apply Configuration
  3. Log displays "Configuration applied" ✓
  4. Done!

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🔧 TROUBLESHOOTING

Issue 1: NVGate Shows "Disconnected"

What it means: Application can't reach NVGate

Solutions (in order):

  1. Is NVGate actually open? Check your screen.
  2. Restart NVGate
  3. Restart the THD application
  4. Check Windows firewall allows localhost connections
  5. Call your IT department and cry

Reality check: 99% of the time NVGate just wasn't open. No shame, happens to everyone.

Issue 2: Measurement Won't Start

What it means: Something blocking the measurement

Solutions:

  1. Click Run Diagnostic - it will tell you exactly what's wrong
  2. Common causes:
    • No sweep configured in NVGate
    • Markers not properly created
    • Wrong window names in configuration

The diagnostic is your friend. Use it!

Issue 3: THD Values Show "--.-" (dashes)

What it means: No data is being read from harmonics

Check these:

  1. Are FFT traces actually visible in NVGate? (Most common issue)
  2. Is the sweep running?
  3. Is there audio output to your speaker?
  4. Are markers properly set up?

Fix one of these and you're golden!

Issue 4: STOP Button Doesn't Work

What it means: Measurement is shutting down but taking its time

Solution: Wait 5 seconds. Seriously. The app is cleaning up.

If it still doesn't respond after 30 seconds:

  1. Close the window
  2. Restart the application
  3. Continue with life

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💡 PRO TIPS

Tip 1: Start Simple

Always use default settings first. Change things later if needed.

Tip 2: Read the Log The log console tells you everything. It's your best friend.

Tip 3: Use Diagnostic When something's wrong, click "Run Diagnostic". It's like magic.

Tip 4: Multiple Measurements One measurement is interesting. Five measurements is scientific.

Tip 5: Document Results Take a screenshot or copy the final THD values. You'll forget otherwise.

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❓ FREQUENTLY ASKED QUESTIONS

Q: Is THD 5% good?

A: For a speaker? Excellent! You can be proud of that equipment. 🎉

Q: Why does THD change with frequency?

A: Because speakers aren't perfect at all frequencies. Some frequencies cause more distortion than others. That's physics being weird.

Q: Can I use this on any speaker?

A: Yes! Desktop speakers, studio monitors, subwoofers, car speakers - if it's connected to NVGate, we can measure it.

Q: How many times should I measure?

A: Once for curiosity. Three times for reliability. Ten times if you're publishing a paper.

Q: Can I export the results?

A: Yes! Copy text from the log console and paste into Excel, Word, or wherever you need it.

Q: What if my project has different settings?

A: Use the Configuration panel to adjust. It's literally made for this.

Q: Does this work over WiFi?

A: No. It only works locally (same computer or local network). WiFi would add too much latency.

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🎓 QUICK REFERENCE

ACTION SHORTCUT RESULT
Launch App Double-click .bat file Window appears ✓
Start Measurement Click ▶ START Metrics begin updating ✓
Stop Measurement Click ■ STOP Log shows "ended" ✓
Run Diagnostic Click "Run Diagnostic" See all [OK] or [FAIL] ✓
Change Config Click ▶ Configuration Apply changes ✓

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📞 BEFORE YOU CONTACT SUPPORT

Gather this information:

  • Screenshot of the error message
  • Last 5 lines of the log console
  • Your NVGate window names
  • Steps you took before the error

This helps us help you faster! 🚀

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You're Ready!
Go measure some THD and make your speakers proud 🎵

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Last Updated: 2026-04-15

Version: 1.0 - User Guide

Format: MediaWiki

For technical details, see DOCUMENTATION_EN.txt

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