GPS Are Incorporated In a Diverse of Consumer Products for Tracking Phones
GPS receivers sometimes take a long time to become ready to navigate after being turned on because it must acquire some basic information in addition to finding GPS satellite signals. This delay can be caused if the GPS device has been unused for days or weeks, or has been transported a significant distance while unused for. The GPS must update its almanac and ephemeris data and store it in memory. The GPS almanac is a set of data that every GPS satellite transmits. When a GPS receiver has current almanac data in memory, it can acquire signals and calculate initial location more quickly.
GPS Hot Start refers to when the GPS enabled handset keeps its last identified location, the satellites which were in view at the time, and also the almanac data in memory, and tries to obtain the same satellites and determine a fresh position based upon the previous data. This is generally the quickest GPS lock but Hot Start only works if the phone is generally in the same location as when the GPS was last turned off.
GPS Warm Start is the term for when the GPS enabled smartphone recalls its last calculated location, and almanac used, but not which satellites were in view. It performs a reset and tries to connect to satellite signals and computes a fresh position. The GPS receiver has a general idea of which satellites tolook for since it saved its last known location and also the almanac data helps determine which satellites are within view. The Warm Start will take longer than the Hot Start although not as much as a Cold Start.
With GPS Cold Start, the device dumps all the previous information, and attempts to find satellites and achieve a GPS lock. This takes more time since there is no known reference information. The GPS enabled handset receiver must try to lock onto a satellite signal from any accessible satellites.
Assisted GPS, also known as A-GPS or AGPS, improves the performance of normal GPS in devices connected to the cellular network. In the United States Sprint, Nextel, Verizon Wireless, and Alltel all use A-GPS. Which is a means of utilizing the cellular network to speed up acquisition of GPS satellites. A-GPS improves location tracking performance of smartphones (as well as other related devices) in a couple of ways:
One way is by assisting to obtain a more rapid “time to first fix” (TTFF). AGPS acquires and stores information in relation to satellite location utilizing the cell network so the position information does not require to be downloaded via the satellite.
A subsequent approach is by assisting locate smartphones when GPS signals are weak or blocked. Because GPS satellite signals may be interfered with by tall buildings, and do not pass through building interiors well AGPS uses proximity to cellular towers to approximate location when GPS signals are not obtainable.
Another way of formulating device position is Triangulation or Mobile Location Services (MLS). Cell Tower Triangulation uses signal analysis data to compute the time it takes signals to travel from your cellular phone to a minimum of three cell towers to calculate location.
To abide by Federal Communications Commission guidelines, cell phone companies have to be in a position to provide authorities with mobile phone latitude and longitude to an precision of 50 to 300 meters. Cell Tower Triangulation isn’t going to always satisfy this requirement. By way of comparison, commercially accessible GPS systems will be able to realize precision right down to 3-10m. This is dependent on a lot of factors, as GPS signals are often quite weak and they are disturbed by numerous variables. With Mobile Location Services (MLS), the GSM cell network provider uses triangulation techniques to try to pinpoint the location of the handset, its accuracy is proven to be less than than that of GPS. MLS is also impacted by factors similar to GPS in the sense of the barriers affecting signal quality and the density of GSM towers to assist in the triangulation calculation. In rural areas location accuracy may be off as much as a mile.
GPS Basics
Smartphone GPS
Much of the discussion surrounding cell tracking, mobile GPS and mobile phone tracking software could be helped by a GPS Satellite primer.
GPS satellites broadcast signals from space that GPS receivers use to provide three-dimensional location (latitude, longitude, and altitude) plus precise time. GPS stands for Global Positioning System and is a network that is made up of 3 main segments: Space Segment, Control Segment and User Segment.
The GPS Space Segment incorporates twenty-four to thirty-two satellites that orbit the earth in medium earth orbit MEO. These satellites are referred to as the GPS Constellation, and they make an orbit once every 12 hours. They are not geosynchronous, they travel at over 7,000 mph. GPS satellites are solar powered but have battery reserve for when they are in the earth?s shadow. They are placed so that there are at least 4 satellites ?visible? from any point on earth. Small rocket boosters on each satellite keep them properly positioned. The satellites last about ten years until all their fuel is exhausted.
GPS Satellites are not communications satellites. Geostationary or communications satellites are parked in space 22,300 miles above the equator. These satellites are used for weather forecasting, satellite TV, satellite radio and most other types of global communications. At exactly 22,000 miles above the equator, the earth’s force of gravity and centrifugal forces are offset and are in equilibrium. This is the ideal location to place a stationary satellite. The earth rotates at about 1,000 miles an hour, and because of their high earth orbit the earth-synchronous satellites need to move at about 7,000 mph to sustain position. This is just about the same speed as GPS satellites, but since geo-synchronous satellites are 10,000 miles further away they stay in place relative to the earth.
The GPS Control Segment made up of Master Control Station, an Alternate Master Control Station, and numerous dedicated and shared Ground Antennas and Monitor Stations that work together to make sure the satellites are working to specification and the information they send to earth is accurate.
The GPS User Segment incorporates of GPS receivers taking the shape of handsets and , laptops, in-car navigation devices and hand-held tracking units along with the people that use them, and the software applications that make them function.
GPS receivers calculate position by precisely timing the signals sent by GPS satellites. This information includes the time the message was transmitted, precise orbital information (the ephemeris), and the general system health and rough orbits of all GPS satellites (the almanac).
GPS tracking, mobile GPS and cell phone track software are getting a lot of interest from individuals, mobile phone businesses and application coders. GPS Tracking and How to Spy. The newest smartphones have GPS position functions to track smartphone position.
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