Self study

Topic : GNSS (Global Navigation Satellite System)

What is GNSS? It is a satellite system that is used to pinpoint the geographic location of a users receiver anywhere in world There are two GNSS systems currently in use 1.USA 2.RUSSIA

The above picture shows the navigational satellites of different country. We can see that these satellites are at a particular height. This layer is called MEO(medium earth orbit). That is it lies between 2000km to 36000km. Most common altitude is approximately 20200km which yields orbital period of 12 hours. So looking on these conditions the satellite is launched at a specific velocity. At space its centripetal force is balanced by gravitational force of earth.

After reaching the space by given conditions it is used to know the position of particals on earth by sending and recieveing signals. The particle distance can be found by triangulation method.

Triangulation is a method of measuring a point by knowing the angles from known points at either end of fixed baseline.Here the unknown point is a particle and known fixed points, that is satellites than the distance of a particle is measured by using formula

In the formula l:distance between satellitesd:perpendicular distance of a point from line l:angle subtended by a ray from satellite to the line l:angle subtended by a ray from satellite to line l.

GNSS applications :In vehicle steering: GNSS vehicle guidance automatically steers the vehicle along all or part of its travel path and can also control an agricultural operations. This system includes a GNSS reciver and antenna for determining the vehicles instantaneous position ,a guidance CPU and automatic steering subsystem integrated with the vehicles electrical power system. The automatic steering subsystem can be interfaced with steering column,thereby steering the vehicle according to instructions received from CPU based upon the vehicle position and predetermined path.

GNSS Surveying using SP80:The spectra precision SP80 is a GNSS receiver. It uses unique Z-blade system to track and process cell available GNSS signals, to provide the most reliable measurements and highest possible accuracies. Using this we can find the area of a land accurately.

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