Getting HDD Locator Calibration Right

By Siggi Finnsson February 13, 2026

To understand calibration, we first must understand signal strength. As its name implies, signal strength is the amount of signal emitted by a transmitter.

Each transmitter is designed to transmit at a constant signal strength, so different makes, models, and lengths of transmitters will transmit at different strengths.

You can think of signal strength like volume. The receiver “listens” to the transmitter, determines how “loud” it is, and provides a numerical value for that volume. The louder the “sound,” the further away you can “hear” it. As you move away from the transmitter, the signal strength therefore decreases and increases again as you move toward it.

The signal strength scale is arbitrary, but values between 0 and 1,200 are common for receivers.

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What Is Calibration?

Since properly functioning transmitters broadcast signal at a constant strength, the signal received at any distance from the transmitter can therefore be equated to a distance. In other words, signal strength equals depth.

Read the complete story in the 2025 HDD Guide.