Methods for Cell Phone Tracking and Mobile Location raise the question: Do you really know where they are?

Different Approaches to Being a Mobile Phone GPS Tracker Raise the Question:  Do you really know where they are?

Across the country and around the world, GPS tracking, mobile GPS and mobile phone track software are getting a lot of attention from consumers, mobile phone companies and application developers.   The most recent smartphones include GPS locator functionality to track phone location.   These features, along with others such as SMS message, internet access and the capability to use other software make smartphones great gadgets.  However GPS satellites aren’t always available, such as when the phone is in a structure such as an school, mall, or even in a car.  That doesn’t mean cell phone locating isn’t available, but it does mean there are other methods of being a tracker.

To track a mobile phone involves several main methods of determining  cell phone location.  GPS Global Positioning System-Satellites, Triangulation, and CellID.   All these technologies convert smartphones into mobile tracking devices.   These systems can be viewed as Network Based, Handset Based or a Hybrid approach.  GPS location is Handset based as it needs software programs installed on the cell phone  in conjunction with GPS hardware.  Triangulation and CellID are Network Based as they use the equipment and data from the cellular provider.  Hybrid systems combine methods to make best use of available information and to make location cell tracking faster.  

GPS on cell phones is what people commonly think of when looking at locating smartphones.   GPS (Global Positioning System) using satellites is the most popular and more accurate means of tracking.   However GPS requires satellites to be in direct line of site of the cell phone. 

It doesn’t work particularly well indoors or in crowded cities. 

If riding in a car the signals might not reach the smartphone.  Some cell phones will store the last known GPS location, others might not.  

Another issue with smartphone GPS tracking is the possibility of wasting the battery.  It is important to be able to remotely adjust how often of taking GPS position.  Choosing real-time or periodic sampling affects both the resolution of finding position as well as battery life.  

GPS receivers, whether in a mobile phone, or a dedicated GPS tracking device, determine location by precisely timing the signals transmitted 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 receivers sometimes take a long time to become ready to use after being turned on because it must acquire some basic information in addition to capturing GPS satellite signals. This delay can be caused if the GPS smartphone  has been turned off for days or weeks, or has been moved a far distance while turned off 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 capture satellite signals and find initial location more quickly. 

GPS Hot Start is when the GPS enabled device  remembers its last calculated position, the satellites that were in view at the time, the almanac data in memory, and tries to connect to the same satellites and calculate a new position based upon the previous data. This is usually the quickest GPS lock but Hot Start only works if the phone is in the same general area as when the GPS was last switched off. 

GPS Warm Start is when the GPS enabled handset  remembers its last known location, and almanac used, but not which satellites were in range. It performs a reset and tries  to find satellite signals and calculates a new position. 

The GPS receiver has a general idea of which satellites toseek because it kept its last known position and the almanac data helps identify which satellites are in range. The Warm Start will take more time than the Hot Start but not as long as a Cold Start. 

With GPS Cold Start, the device dumps all the previous data, and attempts to locate satellites and accomplish a GPS lock. This takes the longest because there is no known reference information.  The GPS enabled handset   receiver has to attempt to lock onto a satellite signal from any available satellites. 

Assisted GPS, also known as A-GPS or AGPS, improves the performance of standard GPS in cell phones connected to the cellular network.   In the United States  Sprint, Nextel, Verizon Wireless, and Alltel all use A-GPS. Which is a means of using the cellular network to speed up acquisition of GPS satellites.  GPS Receivers can get a faster lock in exchange for a few kilobytes of data transmission.

A-GPS assists location tracking performance of smartphones (and other connected devices) in two ways:

The first way is by assisting to obtain a faster “time to first fix” (TTFF). A-GPS acquires and storesinformation about satellite positionusing the cellular network so the coordinates information doesn’t need to be downloaded from the the satellite. 

The next way is by assisting position  cell phones when GPS signals are weak or impeded.  As discussed above GPS satellite signals may be interfered with by tall buildings, and do not penetrate building interiors well. Assisted GPS utilizes proximity to cellular towers to calculate position when GPS signals are not available. 

If satellite signals are not available, or accuracy is less important than battery life, using Cell-ID is a good substitute to GPS cell phone location.  The location of the mobile phone can be determined by the cellular network cell id, which identifies the cell tower the phone is connected to.   By knowing the position of this tower, then you can know approximately where the smartphone  is.  However, a tower can cover a huge area, from a few hundred meters, in high density areas, to several miles in lower density areas. This is why location CellID accuracy is lower than GPS accuracy. Nonetheless tracking from CellID still presents a very good substitute.    

Another method of determining  smartphone location is Triangulation or Mobile Location Services (MLS).  Cell Tower Triangulation uses signal analysis data to calculate the time it takes signals to travel from your phone to at least three cell towers to determine location.   

To comply with Federal Communications Commission guidelines, cell phone companies must be able to provide authorities with smartphone latitude and longitude to an accuracy of 50 to 300 meters.   Cell Tower Triangulation doesn’t always meet this requirement.  By way of comparison commercially available GPS systems can obtain accuracy down to 3-10m.  This depends upon many factors, as GPS signals are often very weak and are affected  by many variables.   With Mobile Location Services (MLS), the GSM cellular network provider utilizes triangulation algorithms to compute the position of the mobile phone, its accuracy is proven to be less than than that of GPS.  MLS is further affected by factors similar to  GPS in the sense of the barriers impeding signal quality and the density of GSM towers to assist in the triangulation effort.   In remote areas location accuracy may be off as much as a mile. 

It may be critical to consider how GPS location software programs handle the data and controls cell phone settings.   Having real time tracking on demand, or preferring to minimize battery use and data transmission should be a minimum requirement.   Generally the application determines the location with a GPS receiver and transmits the tracking data to a server through a data connection. The data connection to the server is usually made using the Internet.  How often GPS samples are taken and how often and by what method the information is sent to the server affect usefulness and costs. 

Consider that there is a basic difference between smartphone GPS Tracking and Navigation.  GPS cell phone tracking is normally associated with a third-party maintaining records of either real-time or historical mobile phone  position, while Navigation deals with the cell phone  user determining how to get from point A to point B.

A really great software package that includes remote control of mobile phone settings, and combines Phone GPS Tracking  with SMS text message, Call Log,  MMS multi-media message monitoring, and a web account for storage and review is PhoneBeagle.  

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