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, Cell tracking, cell phone GPS and cell phone tracker software are attracting attention from consumers, mobile phone companies and application developers.   The latest cell phones have GPS position features to track phone location.   These features, along with others such as SMS message, web access and the capability to use other applications make cell phones 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 when driving.  That doesn’t mean smartphone locating isn’t available, but it does mean there are other methods of being a tracker.

To track a cell phone involves several primary ways of determining  cell phone position.  GPS Global Positioning System-Satellites, Triangulation, and CellID.   All these technologies convert smartphones into mobile tracking systems.   These systems can be viewed as Network Based, Handset Based or a Hybrid approach.  GPS location is Handset based as it requires software applications installed on the cell 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 techniques to make best use of available data and to make position mobile phone tracking faster.  

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

Sometimes thick cloud cover and dense foliage impedes with signals. 

If the phone is in a building, for example your house, mall.  Some smartphones will retain the last known GPS location, others might not.  

Another issue with smartphone GPS tracking is the potential of battery drain.  It is important to be able to remotely adjust the frequency of taking GPS position.  Choosing real-time or periodic sampling affects both the resolution of finding position along with battery life.  

GPS receivers, whether in a mobile phone, or a dedicated GPS tracking device, calculate 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 navigate after it's turned on because it must acquire some basic information in addition to finding GPS satellite signals. This slow start is sometimes caused if the GPS mobile phone  has been turned off for days or weeks, or has been transported a significant 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 compute initial location faster. 

GPS Hot Start is when the GPS enabled device  keeps its last known location, the satellites that were in range before, the almanac data in memory, and makes an attempt to find the same satellites and determine a new 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 switched off. 

GPS Warm Start is when the GPS enabled handset  recalls its last known location, and almanac used, but not which satellites were in view. It resets and attempts  to find satellite signals and computes a new position. 

The GPS receiver narrows the choice of which satellites tolook for because it stored its last known position and the almanac data helps identify which satellites are within view. The Warm Start will take longer than the Hot Start but not as long as a Cold Start. 

With GPS Cold Start, the device deletes 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 mobile phone   receiver has to try 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 cell network.   In the US  Sprint, Nextel, Verizon Wireless, and Alltel all use A-GPS. Which is a means of utilizing the cell network to speed up finding of GPS satellites.  GPS Receivers can get a faster lock in exchange for a few kilobytes of data transmission.

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

The first way is by assisting to obtain a more rapid "time to first fix" (TTFF). AGPS acquires and storesinformation about satellite positionusing the cell network so the coordinates information doesn’t require to be downloaded via the satellite. 

Another way is by helping position  handsets 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. AGPS uses proximity to cellular towers to compute 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 viable alternative to GPS mobile phone location.  The location of the device 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 mobile phone  is.  But, 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 precision is lower than GPS accuracy. Nevertheless tracking from CellID still provides a very useful substitute.    

Another way of formulating  smartphone position 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, cellular 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 less than 10 meters.  This depends upon many factors, as GPS signals are often very weak and are impacted  by many variables.   With Mobile Location Services (MLS), the GSM cell network provider uses triangulation algorithms to calculate the position of the cell phone, 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 strength and the density of GSM towers to help in the triangulation calculation.   In remote areas position accuracy may be off as much as a mile. 

Generally speaking it is a matter of what location tracking system is available, and the need for accuracy.  Hybrid methods are emerging that use various techniques in tandem to provide best available location given available resources.   Typically 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 data is sent to the server affect usefulness and costs. 

Keep in mind that there is a fundamental difference between cell phone GPS Tracking and Navigation.  GPS phone tracking is typically associated with a third-party keeping 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 Mobile Phone Tracking  with SMS text message, Call Log,  MMS multi-media message monitoring, and a web account for storage and review is PhoneBeagle.  

Follow this link if you are interested in    Mobile Monitoring Software  compatible with BlackBerry  and  Android  Smartphones, used or Parental Monitoring and Small Business Employee Monitoring .  

Visit this link for more information regarding the latest software for
Mobile Phone Tracking .