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

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

Mobile communications means more than just making a phone call while moving.    The latest mobiles include GPS locator functionality to track phone location.   These features, and others such as text messaging, internet access and the capability to utilize other software make mobiles great gadgets.  But GPS satellites aren’t always available, for example when the handset is in a structure such as an school, mall, or even in an automobile.  That doesn’t mean mobile 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 ways of calculating  mobile phone location.  GPS Global Positioning System-Satellites, Triangulation, and CellID.   All these technologies transform cell phones 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 requires software programs installed on the mobile phone  in conjunction with GPS hardware.  Triangulation and CellID are Network Based as they use the equipment and information from the wireless provider.  Hybrid systems combine methods to make best use of available information and to make location cell tracking faster.  

Mobile phone GPS is what people usually think of when looking at locating mobile phones.   GPS (Global Positioning System) using satellites is the most common and more accurate way of tracking.   However GPS requires satellites to be in direct line of site of the cell phone. 

Sometimes heavy cloud cover and thick foliage impedes with reception. 

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 thing with handset GPS location is the potential of battery drain.  It is important to be able to remotely adjust the frequency of taking GPS position.  Selecting real-time or periodic sampling affects both the accuracy of determining location as well as how long the battery will last.  

GPS receivers, whether in a cell 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 condition and estimated orbits of all GPS satellites (the almanac).  GPS receivers sometimes take longer 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 when the GPS cell phone  has been turned off for days or weeks, or has been moved 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 determine initial location more quickly. 

GPS Hot Start is when the GPS enabled mobile phone  recalls its last known location, the satellites that were in range at the time, the almanac information in memory, and attempts to find the same satellites and determine a new position based upon the previous information. This is usually 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 when the GPS enabled mobile phone  recalls its last calculated position, and almanac used, but not which satellites were in view. It resets and tries  to obtain satellite signals and computes a new position. 

The GPS receiver narrows the choice 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 achieve 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 handsets connected to the cellular network.   It downloads the ephemeris and helps triangulate the cell phone   general position.  GPS Receivers can get a faster lock at the expense of a few kilobytes of data transmission.

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

The first method is by helping to obtain a more rapid "time to first fix" (TTFF). A-GPS acquires and archivesdata about the location of satellitesvia the cell network so the coordinates information doesn’t require to be downloaded from the the satellite. 

The next way is by helping locate  handsets when GPS signals are weak or impeded.  As discussed above GPS satellite signals may be impeded by tall buildings, and do not penetrate building interiors well. AGPS utilizes proximity to cellular towers to compute location 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 useful alternative to GPS mobile phone tracking.  The location of the mobile phone can be computed by the cell 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 cell phone  is.  But, a tower can cover a huge area, from a few hundred meters, in high population 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 viable alternative.    

Another way of determining  mobile phone 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 estimate location.   

To comply with Federal Communications Commission guidelines, cellular phone companies must be able to provide authorities with cell phone 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 achieve accuracy down to 3-10m.  This depends upon many factors, as GPS signals are often very weak and are affected  by many environmental factors.   With Mobile Location Services (MLS), the GSM cell network provider utilizes triangulation algorithms to try to pinpoint the position 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 interference affecting 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 important to consider how GPS location software applications handle the data and controls handset settings.   Having real time tracking on demand, or preferring to minimize battery use and data transmission should be offered.   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 over 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. 

Keep in mind that there is a basic difference between handset GPS Tracking and Navigation.  GPS mobile phone tracking is usually related to someone keeping records of either real-time or historical smartphone  position, while Navigation deals with the handset  user figuring out how to get from point A to point B.

A really great software package that includes remote control of smartphone settings, and combines Cell Phone 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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