Each GPS satellite continuously emits a navigation message to calculate latitude and longitude. Information consist of a 50 Hz signal containing data and satellite orbits, clock corrections and other system parameters satellite status information.
Complete data signal consists of 37,500 bits and transmitted at a rate of 50 bits / s, hence a total of 12.5 minutes required to receive full signal. This time is necessary GPS receiver until it becomes possible first determination of position, that if there is information stored on satellites or information no longer valid. The data signal is divided into 25 frames, each having a length of 1500 bits (which means a range of 30 seconds each transmitted frame).
A typical reason for which satellites are marked bad, stems from the need to correct orbit. In this case, the satellite thrusters are started and defect marking is removed as soon as possible, once the satellite has stabilized in its new orbit.
When Ephemeris and Almanac data are stored in the GPS receiver, time to first position determination will depend on the current. If the recipient has no contact with the satellite for a long time, the first position determination will take longer.
Possible sources of interference
- Natural sources
GPS operations in space weather deteriorates in two ways: direct interference caused by radio noise emissions of the Sun on the same frequency band or by capturing GPS signal. Solar radio emissions associated with solar flares and their impact can affect reception on half the planet, half of which was, at that time, facing the sun.
PS receivers used in car windows metal inserts, such as misting, or colored foil, can act as a Faraday cage type, degrading reception just inside the car.
Some countries allow the use of http://gps-phonetracker.net/ and reception of GPS signals even in places covered or closed, however, in accordance with EU laws, the use of repeaters is prohibited because signals can cause interference with other GPS receivers that can receive data both from GPS satellites and the repeater.
Given the potential of natural and artificial noise, interference numerous e-solving techniques continue to be developed. The first is that we do not rely on GPS as a sole source. For example, airplane pilots must have a backup plan in case of malfunctioning of GPS.
Gps are used in mobile industry also. It used by phone makers to track their mobile devices if one of them is stolen. But their system are not so good and other companies created tools that do the same thing, one of them is SITE . They provide a user friendly experience to track their mobile device!
GIS (Geographical Information Systems)
Suppose we are interested to vacation in a corner of the planet. But we want to make sure that we spend a vacation without unpleasant surprises from the weather or not to meet with any natural disaster, or simply not to choose an area with high pollution.
We could say that we are very demanding people, but on no account think there is any travel agency to warn of the chosen area. We could call yet from a GIS system to inform us in terms of climate in the chosen area over the last, say, 30 years of natural disasters occurred or to trace simply a map of industrial areas with a high risk of pollution the last 100 years.
What is a GIS?
More broadly, a GIS is an information system used for modeling, processes and structures that reflect the real world, including past events in order to understand, analyze and manage resources and facilities.
A GIS can be described as a system management database, which usually takes the user data in an interactive graphic that can be queried and analyzed. However, do not imagine that GIS is a purely hardware, it is an ensemble consisting of computer equipment, software, people, methods and rules that allows data processing and exploitation of geo-topographic maps.
How to enter data in the system?
The maps can be digitized or drawn with the mouse to collect dates the different elements. Electronic devices can also convert the scan lines and points on a map in digital format.
What is the use of GIS systems? benefits and risks.
Advantages of Using a GIS:
- The data are better organized
- Eliminate redundancy in data storage
- Facility Update
- Analysis, statistics and we searches much easier
- Users are more productive
- High costs
- Changes in land
- Difficulties on staff training
Geographic information system technology (GIS) can be used for scientific investigations, resource management and development planning. Scopes of GIS are countless. I have given only examples of geo-topography, but GIS is applicable on many other areas, such as: Health, Social Sciences, Banking & Finance, Forensic Science, Tourism, Geology, Environment etc. But the best would be to enlighten you through concrete examples. I found all kinds of projects are currently being conducted and based on GIS and hope to be enlightening.