SHT-3-F FOG North-Finder

1.Product use and scope of use

SHT-3-F FOG North-Finder ( hereinafter referred to as the product ) is mainly used to quickly and independently determine the true north direction.

This document is applicable to the installation, use and maintenance of products.

2. Composition and working principle of products

The product is mainly composed of fiber optic gyroscope, accelerometer circuit, transposition structure control circuit, processor solution circuit and power conversion circuit.

Based on Sagnac effect, the product uses the laser as the light source and uses the fiber to form an annular optical path to measure the optical path difference caused by the rotation of the positive and negative beams with the fiber ring, so as to obtain the angular increment information of the sensitive axis and measure the angular velocity of the earth rotation.  When working, the angular velocity components of the earth rotation at three different positions are measured by the transposition structure, and the azimuth information of the product is calculated according to the measured angular velocity components of the earth rotation.  At the same time, the axial inclination data of the product are obtained through the two-axis accelerometer, which can be used to adjust the carrier platform and correct the inclination of the north seeker.

3 .Main technical

3.1 Power supply

a）Power supply voltage：9-36Vdc,  Power supply current:>1A;

b）Transient current: ≤1A,  Steady working current：≤0.5A.

3.2  Main technical

3.2.1 Working mode : static.   

3.2.2 Preparation time : ≤ 30 s.   

3.2.3 North-seeking time : ≤ 3min.   

3.2.4 Measurement range of transverse and longitudinal inclinations : －15º～＋15º。

3.2.5 Inclination accuracy : ≤0.02º（1σ）。 

3.2.6 North-seeking accuracy : ≤0.03º（1σ）。   

3.2.7 Azimuth measurement range : 0º-360º  

3.2.8 Working latitude ( design assurance ) : 60°South to 60° North.   

3.2.9 Digital output form : RS-422.  Optional RS-232, RS-485  

3.2.10 Weight : 5Kg  

3.2.11 Communication protocol

Digital communication adopts differential RS-422 asynchronous serial full duplex communication mode.   

Serial communication takes a byte as the basic transmission unit, the baud rate is 38400bps, a byte transmission effective bits are 10 bits : 1 bit start bit ( logic 0 ), 8 bit data bit, no parity check, 1 bit stop bit ( logic 1 ).  8-bit data is always low in the front, high in the back.  For a multi-byte number, always first pass low byte, then pass high byte.

Table 3 Output data frame format ( 10 bytes )

Table 4 Input command frame format ( 4 bytes )

3.3 Environmental conditions  

3.3.1 Temperature range : -40℃～+60℃.   

3.3.2 Storage temperature range : -55℃～+75℃.  

3.3.3 Impact:  10g, 11ms, half sine wave,

Direction : Installation direction,

Times : 3.   

3.3.4 Vibration: 5Hz～5.5Hz，25.4mm；5.5Hz～200Hz，1.5g（rms） 

Direction : Installation direction.  

Time : 15min.   Cycle times : 3 times.   

3.3.5 Damp heat  At the temperature of 30℃,60℃ and relative humidity of ( 95 ± 3 ) %, the metal surface should work normally without corrosion and no blistering, wrinkling, cracking or shedding of the protective coating.   

3.3.6 Rain:  

Rain intensity : 13cm/h, rain time : 1h, rain angle : four sides and top, nozzle diameter : 1mm～2mm.

Download：

（英文）SHT-3-F.pdf