Geotech News| Geotech Instrument Co., Ltd.

Introduction: The “Invisible Battlefield” of Geological Exploration

In mineral exploration and archaeological surveys, subtle geomagnetic variations (even 0.1nT-level differences) often hold critical clues to billion-ton iron deposits or millennia-old artifacts. However, traditional magnetometers frequently suffer from data distortion due to diurnal interference and electromagnetic noise. The JPMG Proton Magnetometer achieves world-leading ±0.1nT absolute accuracy through its OCXO temperature-controlled crystal oscillator and dual-probe synergy technology. This article dissects its core technical principles, revealing the underlying logic of high-precision magnetic gradient measurement.

I. Gradient Formula Breakdown: How 0.4m Spacing Neutralizes Diurnal Interference

Diurnal variation is the most significant source of measurement interference. Single-probe devices require base station synchronization for correction, while JPMG’s (Proton Magnetometer) dual-probe gradient mode mathematically eliminates this challenge:

1. Gradient Calculation Formula:

Gradient Value (mnT)=0.4mBlower−Bupper

By synchronously sampling magnetic fields at a fixed 0.4m vertical spacing between probes, diurnal fluctuations are canceled out, isolating only the target area’s magnetic anomalies.

2. Field Case Study:

At an iron ore site, gradient values exceeding 3000nT/m precisely delineated ore boundaries, aligning with drilling results within **<3% error margin**.

II. OCXO: The “Timekeeper” Behind Microsecond Synchronization

Proton precession frequency measurement accuracy directly determines magnetic field precision. JPMG’s OCXO (Oven-Controlled Crystal Oscillator) technology overcomes traditional crystal oscillator temperature drift:

1. Microsecond-Level Timing:

GPS/BeiDou multi-mode timing accuracy: 1μs, ensuring strict synchronization between base and mobile stations.
Oscillator stability: **<5×10⁻⁹**, limiting frequency error to **<0.001 Hz** over 10-second cycles (equivalent to 0.023nT field error).

2. Anti-Interference Comparison:

Standard oscillators at **-20°C**: 0.1ppm frequency drift → 2.3nT error.
OCXO in **-40°C to +55°C**: <0.01ppm drift → **<0.23nT error**.

III. Dual-Coil Reverse Series: The “Final Boss” of Electromagnetic Noise

Alternating electromagnetic fields from power lines or vehicle engines severely degrade signal quality. JPMG’s (High-Sensitivity Magnetometer) dual-coil reverse-series probe design neutralizes noise:

1. Principle Diagram:

External interference fields induce opposing currents for mutual cancellation

2. Field Data:

Under 500V power lines, single-coil SNR drops to 3.
Dual-coil mode maintains SNR at 9.

IV. Engineering Philosophy: Sensor Spacing Optimization

JPMG’s 0.4m probe spacing balances engineering trade-offs:

1. Sensitivity vs. Portability:

Every 0.1m increase boosts gradient resolution by 20% but adds 30% probe weight.
At 0.4m spacing, total system weight is 2.57kg (host: 1.57kg + probes: 1.0kg), achieving optimal resolution-portability balance.

2. Vibration Resistance:

Aluminum probe rod with mortise-and-tenon joints limits vibration-induced deformation to **<0.05nT/m**.

Long-tail Keyword: High-Precision Magnetic Gradiometer Sensor Spacing Optimization

Conclusion: Redefining Industry Standards for Exploration Accuracy

The JPMG Proton Magnetometer combines OCXO timing mastery, dual-probe spatial analysis, and military-grade anti-interference design, ushering geomagnetic exploration into the **”sub-nanotesla era”. From 5,000-meter plateau mineral surveys** to pinpointing 0.5m-diameter urban pipelines, this China-engineered solution continues to rewrite global precision benchmarks.