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Fiber Optic

Gyro North Seeker – User Manual 

1. Overview

1.1 Product Purpose

The gyro north seeker is used to rapidly and autonomously determine true north. It relies on two fundamental properties of the gyroscope – precession and rigidity – to achieve autonomous north-seeking. By tracking the earth's rotation rate with a high-precision fiber optic gyro and processing the resulting signal, the instrument computes the angle between the gyro's main axis and true north, providing azimuth information to the carrier platform.

1.2 Product Composition

The gyro north seeker is an electromechanical instrument consisting of a fiber optic gyro, an accelerometer, a mechanical rotation control mechanism, and an embedded computer.

1.3 Key Technical Parameters

● North-seeking range: ±70° (latitude range)

● North-seeking accuracy: ≤0.02° (1σ)

● Repeatability: ≤0.1° (1σ)

● North-seeking time: ≤3 min

● Circular linearity (1σ): ≤0.02°

● Operating voltage: AC220V ±10%, 50Hz

● Power consumption: ≤ 50W

● Weight: ≤ 7.5kg

1.4 Electrical Performance

Insulation resistance: Under standard atmospheric conditions, the insulation resistance between independent circuits of the gyro north seeker, and between the circuits and the housing, shall be no less than 100 MΩ.

1.5 Maintainability

● MTBF ≥ 1000 hours

● MTTR ≤ 30 min

2. Environmental Requirements

● Operating temperature: -40℃ to +50℃

● Storage temperature: -55℃ to +65℃

Sand and Dust

Under the sand and dust conditions specified in Clause 2 of GJB150.12, the gyro north seeker shall not exhibit any of the following:

● Mechanism binding, jamming, or malfunction

● Short-circuiting or malfunction of electrical components

● Dust accumulation on internal optical or mechanical parts

Salt Fog

The gyro north seeker shall meet the salt fog requirements of GJB150.11.

Humid Heat

Relative humidity: 95%; temperature: 30±2℃; storage duration: 72 hours. Insulation resistance shall be no less than 2 MΩ, metal surfaces shall show no corrosion, and coatings shall show no blistering or peeling, with the unit remaining fully operational.

Vibration

Sinusoidal sweep vibration requirements:

● Frequency range 5Hz–5.5Hz: vibration displacement (peak-to-peak) 25.4mm

● Frequency range 5.5Hz–200Hz: vibration acceleration 1.5g

● Sweep time: 12 min

● Vibration axes: 3 (X, Y, Z)

● Duration per axis: 2 hours

Shock

Shock waveform: half-sine pulse. Peak acceleration: 20g, pulse width 11ms, 3 shocks per axis (X, Y, Z).

Collision

Peak acceleration: 10g; pulse width: 16ms; collision rate: 80 collisions/min along the vertical axis; number of collisions: 1000±10; collision direction: perpendicular to the mounting plane.

Road Test

Total road-test distance: 500 km, consisting of:

● Dirt/gravel road: 20–30 km/h, 300 km

● Asphalt/concrete road: 30–40 km/h, 200 km

Electromagnetic Compatibility

EMC performance shall comply with the relevant requirements of GJB151A-97.

Rain

● Rain intensity: 6mm/min

● Rain angle: 45° from the top, 45° from each of the four sides

● Duration: 60 min

● Equipment state: unpowered

Magnetic Field

Under a magnetic flux density of (3±0.5)×10⁻⁴ T, the gyro north seeker's performance shall meet the specified technical requirements.

3. External Interfaces

3.1 Power Interface

The power interface uses connector: J599/20KA98PN

Table 1  Communication Interface Pin Definitions