SNS / SNR and Auto-Gating in Night Vision: What They Are and Why They Matter

1. What is SNR / SNS

SNR (Signal-to-Noise Ratio) measures how much useful image signal you get compared to noise.

• High SNR → clean, sharp, detailed image

• Low SNR → grain, snow, poor visibility

Typical values

• SNR 16–20 — old Gen 2

• SNR 22–25 — entry-level Gen 3

• SNR 26–30 — modern military Gen 3

• SNR 30–33+ — premium unfilmed

• SNR 34–38+ — top-tier (L3 Unfilmed / Photonis 4G Max)

Why SNR is more important than FOM

FOM = Resolution × SNR,
but SNR determines real-world clarity in darkness.

2. What is Auto-Gating

Auto-gating rapidly modulates the photocathode input, protecting the tube and stabilizing the image.

Auto-gating prevents

• headlight and flashlight bloom

• overexposure

• large halos

• image washout

• premature tube wear

• instability in mixed lighting

It is essential for urban, tactical and vehicle use.

3. How SNR and Auto-Gating work together

• SNR = clarity and detail

• Auto-gating = stability and protection

Together they create the modern performance standard of Gen 3 NVGs.

4. Comparison

5. What to look for when buying NVGs

• SNR 28+ recommended

• Auto-gating required

• FOM is not meaningful without high SNR