Cell Phone Location Strategies

Friday , 4, October 2013 Leave a comment

GPS tracking, cell phone GPS and cell phone tracking programs are getting a lot of interest from potential customers, cellphone businesses and application designers. The most up to date mobile phones feature GPS location features to track mobile phone location.
 Phone Tracking
GPS receivers, regardless of whether inside a mobile phone, or simply a dedicated Portable gps tracking system, determine location through process of precisely timing the signals transferred by GPS satellites. This data consists of the moment the message was transmitted, highly accurate orbital details (formally referred to as the ephemeris), plus the basic system state and calculated orbits of all GPS satellites (formally called the almanac). GPS receivers sometimes take a long time to become ready to use after it’s turned on because it must acquire some basic information in addition to capturing GPS satellite signals. This slow start can be caused if the GPS smartphone has been turned off for days or weeks, or has been transported a far 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 satellite signals and find initial position faster.
GPS Hot Start describes whenever the GPS enabled mobile phone keeps its last calculated location, the satellites that were in view before, and also the almanac data in memory, and makes an attempt to find the same satellites and calculate a new location based upon the previous information. This is generally the quickest GPS lock but Hot Start only works if the phone is in the same general area as when the GPS was last turned off. GPS Warm Start means whenever the GPS enabled mobile phone keeps its last calculated position, and almanac used, but not which satellites were in range. It performs a reset and tries to obtain satellite signals and calculates a new location. The GPS receiver narrows the choice of which satellites toseek since it kept its last known position and also the almanac data helps determine which satellites are in range. The Warm Start will need longer compared to Hot Start but not as much as a Cold Start. With GPS Cold Start, the device deletes all the previous information, and attempts to find satellites and complete a GPS lock. This takes the longest since there is no known reference information. The GPS enabled handset receiver must try to lock onto a satellite signal from any available satellites.
In order to have better GPS lock times mobile phone manufacturers and network operators introduced Assisted GPS technology. It downloads the ephemeris helping triangulate the mobile phone basic position. GPS Receivers can get a quicker lock at the expense of a few kilobytes of data transmission. Assisted GPS, also called A-GPS or AGPS, improves the performance of normal GPS in cell phones connected to the cell network. In America Sprint, Nextel, Verizon Wireless, and Alltel all use Assisted GPS. This is a means of utilizing the cellular network to speed up finding of GPS satellites.
A-GPS assists location tracking functions of cell phones (and also other connected devices) in a couple of ways:
One way is by helping to acquire a more rapid “time to first fix” (TTFF). Assisted GPS gets and stores information concerning the location of satellites via the cell network and so the position data does not require to be downloaded via the satellite.
The other process is by assisting locate cell phones when GPS signals are weak or impeded. Because GPS satellite signals may be impeded by tall structures, and do not penetrate building interiors well A-GPS utilizes proximity to cellular towers to calculate location when GPS signals are not available.
When satellite signals are not available, or accuracy is less important than battery life, making use of Cell-ID is a good substitute to GPS cell phone location. The location of the smartphone can be determined by the cell network cell id, which pinpoints the cell tower the cell phone is using. By understanding the position of this tower, then you can know approximately the place that the mobile phone will be. Nonetheless, a tower can cover a huge area, from a couple of hundred meters, in higher populationdensity regions, to several miles in lower density zones. For this reason location CellID precision is less than than GPS accuracy. Nevertheless tracking via CellID still presents quite a useful alternative.
Another method of determining smartphone position is Triangulation or Mobile Location Services (MLS). Cell Tower Triangulation uses signal analysis data to calculate the time it takes signals traveling from the telephone to at least 3 cell towers to determine position.