1 Purpose and Application Range
The North Seeking Device (hereinafter referred to as the product) is mainly used for quickly and independently determining the true north direction.
2 Composition and Working Principle
The product is mainly composed of a fiber optic gyroscope, accelerometer circuit, rotation structure control circuit, processor calculation circuit, and power conversion circuit.
The product is based on the Sagnac effect, using an optical fiber to form a ring optical path to measure the optical path difference caused by the rotation of the optical fiber ring for the two beams of light, thereby obtaining the angular increment information of the sensitive axis and measuring the Earth’s rotation angular velocity. During operation, the rotation structure is used to measure the Earth’s rotation angular rate components in three different positions, and the azimuth information of the product is calculated based on the measured Earth’s rotation angular rate components. At the same time, the two-axis accelerometer is used to obtain the tilt angle data of the product axis, which can be used for platform calibration and north seeking device tilt correction.
3 Main Technical Indicators
1.1 Power Supply
- Power supply voltage: 9-36VDC;
- Peak power consumption ≤12W.
1.2 Main Technical Indicators
- Operation mode: Static.
- Preparation time: ≤30s.
- North seeking time: ≤3min.
- Measuring range of transverse and longitudinal inclination angles: -15º～+15º.
- Inclination accuracy: ≤0.02º (1σ).
- North seeking accuracy: ≤0.06º and 0.1º optional (1σ).
- Azimuth angle measuring range: 0º-360º.
- Working latitude (design guarantee): 65ºS～65ºN.
- Altitude >4500 meters.
- Digital output form: RS-422. Optional RS-232, RS-485, CAN.
- Weight: ≤3.5Kg.
- Communication protocol (customizable)
Digital communication uses differential RS-422 asynchronous serial full-duplex communication.
Serial communication takes one byte as the basic transmission unit, with a baud rate of 38400bps. One byte transmission has 10 valid bits: 1 start bit (logical 0), 8 data bits, no parity check, 1 stop bit (logical 1). In the 8-bit data, the low bit is first, and the high bit is last; for a multi-byte number, the low byte is transmitted first, followed by the high byte.
1.3 Environmental Conditions
- Operating temperature range: -40℃～+70℃.
- Storage temperature range: -55℃～+70℃.
- Shock
10g, 11ms, half-sine wave, direction: installation direction, number of times: 3 times.
- Vibration
5Hz～5.5Hz, 25.4mm; 5.5Hz～200Hz, 1.5g (rms); direction: installation direction; time: 15min; number of cycles: 3 times.
- Wet heat
Under conditions of 30℃ and 60℃, with a relative humidity of (95±3)%, it should work normally, with no rust on metal surfaces, and no blistering, wrinkling, cracking, or peeling of the protective coating.
- Rain
Rain intensity: 13cm/h, rain time: 1h, rain angle: four sides and top, nozzle diameter: 1mm～2mm.
4 Dimensions
