Understanding TVG (Time Variable Gain) on Garmin LiveScope LVS32 and LVS34

TVG (Time Variable Gain) is a setting on Garmin LiveScope that helps balance sonar returns by adjusting the strength of echoes based on their distance from the transducer. It’s designed to ensure that objects further away appear with the same intensity as those closer, preventing weak returns from fading out in deeper water. However, using TVG incorrectly can result in lost detail, especially when tracking fish or your lure.

What Does TVG Do?

TVG modifies how sonar gain is applied across different distances. Without TVG, objects closer to the transducer appear much stronger than those farther away, making it difficult to see distant fish or structure clearly.

• Higher TVG: Weakens strong returns close to the transducer and boosts weaker returns farther away.
• Lower TVG: Keeps the original signal strength, making nearby targets appear much stronger than distant ones.

When Should You Adjust TVG?

TVG is most useful in deep water, where sonar returns naturally weaken as they travel farther. However, in shallower water, too much TVG can actually reduce image quality. Here’s when to adjust it:

• Deep Water (Over 20-30 Feet): Increasing TVG can help balance the display and prevent distant fish or the bottom from fading out.
• Shallow Water (Less Than 15 Feet): Keeping TVG lower preserves the clarity of closer returns and avoids washing out the image.
• Suspended Fish: If you’re targeting fish that are mid-water column, setting TVG too high may make them harder to see.
• Close-Range Fishing: If you’re watching your bait or tracking fish up close, a lower TVG setting ensures they remain visible.

TVG Settings: What Each Level Does

Garmin provides four TVG levels:

• Off: No compensation. Best for shallow water and tracking fish or lures up close.
• Low: Slight compensation, good for medium depths while keeping strong targets visible.
• Medium: Balances returns more evenly across the screen, useful in deeper water.
• High: Strongest compensation, making distant returns stand out but potentially muting nearby fish or your lure.

The Trade-Off: Strong Returns vs. Balanced Visibility

While TVG can help even out your screen, there are downsides to setting it too high:

• High TVG Can Remove Close-Range Detail: If set too high, TVG will fade out fish and your lure when they’re close to the transducer.
• Low TVG May Make Distant Returns Hard to See: If you’re fishing deep and TVG is off, fish and structure further out might be too faint to detect.
• Fast-Moving Fish Can Be Harder to Track: Higher TVG settings may smooth out real-time movements, making fast-moving fish or bait harder to see.

Practical Tips for Adjusting TVG

1. Start at Low or Off: Only increase if deeper fish or bottom structure start fading out.
2. Increase Gradually in Deeper Water: Move from Low to Medium as needed, but avoid going straight to High unless necessary.
3. Watch How Fish Appear at Different Depths: If fish are harder to see the farther out they are, a slight increase in TVG may help.
4. Keep It Lower When Tracking a Lure: If you want to see your lure easily, a lower TVG setting is better.

Final Thoughts

TVG is a great tool for refining your LiveScope image, but it should be adjusted based on depth and fishing style. Keeping it at Low or Off in shallow water and increasing it slightly in deep water ensures the best visibility. If you’re struggling to see distant returns, TVG can help, but always balance it with Gain and Noise Reject for the clearest image.