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By Admin, May 4, 2010

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 most up-to-date mobile phones include GPS locator features to track phone location.   These features, and others such as SMS message, web access and the capability to utilize other software make mobiles great gadgets.  However GPS satellites aren’t always available, such as when the handset is in a structure such as an office, mall, or even in a car.  That doesn’t mean mobile phone locating isn’t possible, but it does mean there are other ways of being a tracker.

To track a mobile phone involves several main ways of formulating  cell phone location.  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 needs software programs installed on the smartphone  in conjunction with GPS hardware.  Triangulation and CellID are Network Based as they use the equipment and information from the cellular provider.  Hybrid systems combine techniques to make best use of available information and to make position cell phone tracking faster.  

Mobile phone GPS is what people commonly think of when considering locating mobile phones.   GPS (Global Positioning System) using satellites is the most common and more accurate technology of tracking.   But GPS requires satellites to be in direct line of site of the mobile phone. 

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

If the phone is in a structure, for example your house, mall.  Some cell phones will store the last known GPS location, others might not.  

Another thing with cell phone GPS location is the potential of draining 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 accuracy of finding position along with battery life.  

GPS receivers, whether in a cell phone, or a dedicated GPS tracking device, compute position by precisely timing the signals sent by GPS satellites.  This data 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 longer to become ready to use after being turned on because it must acquire some basic information in addition to finding GPS satellite signals. This slow start can be caused when the GPS cell phone  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 capture satellite signals and determine initial position more quickly. 

GPS Hot Start is when the GPS enabled handset  remembers its last known location, the satellites that were in view at the time, the almanac data in memory, and attempts to connect to the same satellites and calculate a new position based upon the previous information. 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 smartphone  recalls its last known 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 has a general idea of which satellites tolook for because it stored its last known position and the almanac data helps identify which satellites are in range. The Warm Start will take longer 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 more time because there is no known reference information.  The GPS enabled cell phone   receiver has to attempt to lock onto a satellite signal from any available satellites. 

In order to have better GPS lock times cellular manufacturers and network operators developed Assisted GPS technology.   It downloads the ephemeris and helps triangulate the device   general position.  GPS Receivers can get a faster lock in exchange for a few kilobytes of data transmission.

A-GPS assists location tracking functions of cell phones (and other connected devices) in two ways:

One way is by assisting to obtain a faster “time to first fix” (TTFF). Assisted GPS acquires and storesinformation about the location of satellitesusing the cell network so the position information does require to be downloaded from the the satellite. 

Another way is by assisting position  cell phones 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 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 alternative to GPS smartphone tracking.  The position of the cell phone can be determined by the cellular network cell id, which identifies the cell tower the phone is using.   By knowing the location 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 density areas, to several miles in lower density areas. This is why location CellID precision is lower than GPS accuracy. Nonetheless tracking using CellID still presents a very good substitute.    

Another way of calculating  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 determine location.   

To comply with Federal Communications Commission guidelines, cell phone companies must be able to provide authorities with device latitude and longitude to an accuracy of 50 to 300 meters.   Cell Tower Triangulation doesn’t always meet this requirement.  For comparison commercially available GPS modules can achieve accuracy down to 3-10m.  This depends upon many factors, as GPS signals are often very weak and are impacted  by many environmental factors.   With Mobile Location Services (MLS), the GSM cellular network provider uses triangulation algorithms to compute the position of the handset, its accuracy is proven to be much worse than that of GPS.  MLS is further impacted 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 rural areas location accuracy may be off as much as a mile. 

In general it comes down to what location tracking system is available, and the requirements 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 impact usefulness and costs. 

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

A really great software package that includes remote control of cell 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.  

Follow this link if you are interested in    Cell Phone 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
Cell Phone Tracking .

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By Admin, April 4, 2010

Before long GPS will become almost as common as the telephone, or more likely included with every mobile phone.  GPS can determine locations accurate to a matter of.  In fact, incredibly with advanced forms of GPS it is possible to make measurements to less than a centimeter!

It’s just like assigning every square meter on the planet its very own address.  GPS receivers have become very affordable as they have been miniaturized to just a few integrated circuits.  These days GPS is finding its way into cars, boats, planes, construction equipment, movie making gear, farm machinery, laptop computers and especially  cell phones.

Tracking cell phones is a popular topic with a lot of interest.   A lot of the discussion dealing with GPS tracking, mobile GPS and mobile phone tracker software applications could be helped by a GPS Satellite introduction and glossary.

GPS stands for Global Positioning System.   GPS satellites broadcast signals from medium earth orbit that GPS receivers use to estimate three-dimensional location (latitude, longitude, and altitude) plus precise time.  The GPS system is composed of 3 main segments: Space Segment, Control Segment and User Segment. 

The GPS Space Segment is comprised of 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 are orbiting twice a day.  They are not geostationary, but rather move at over 7,000 mph.  They are solar powered but have battery reserve for when they are in the earth’s shadow. They are positioned so that at any given time there are at least 4 satellites ‘visible’ from any point on earth.  Small rocket boosters on each satellite keep them flying in the correct path.   The satellites last about ten years until all their fuel runs out. 

GPS Satellites are not communications satellites.   Geostationary or communications satellites use a higher altitude 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 gravitational force and centrifugal forces are canceled and are in equilibrium. This is the ideal location to park a stationary satellite.   The earth rotates at about 1,000 miles an hour, and because of their high earth orbit the geo-synchronous satellites need to move at about 7,000 mph to maintain position.  This is approximately the same speed as GPS satellites, but since geostationary satellites are 10,000 miles further away they don’t move relative to the earth. 

The GPS Control Segment includes Master Control Station, an Alternate Master Control Station, and a host of dedicated and shared Ground Antennas and Monitor Stations that work together to ensure the satellites are working correctly and the information they beam down to earth is accurate. 

The GPS User Segment includes of GPS receivers  taking the shape of devices and , laptops, in-car navigation devices and hand-held tracking units along with the people that use them, and the software programs that make them work.  

GPS receivers calculate position by precisely timing the signals transmitted by GPS satellites.  This data 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). 

Keep in mind that there is a basic difference between handset GPS Tracking and GPS Navigation.  GPS cell phone tracking is typically related to a third-party keeping records of either real-time or historical cell phone  location, while Navigation deals with the cell phone  user determining how to get from point A to point B.  Neither use works without some sort of third-party software application.

A really great software package that features  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 .

Global Satellite System Frequently Asked Questions

Why does GPS receiver only work outside?
GPS satellites are positioned in their orbits to be sure that from any location on the globe there are at least four satellites visibile at all times. Although the satellites use radio signals, the signal needs a clear of site to the receiver. If the GPS satellite slips below, or a building, or even heavy cloud cover, the radio signal may be lost.  

What do the satellites do?
The GPS satellites are broadcasting the time. Both the satellite and the GPS receiver use atomic clocks for extreme accuracy.  By comparing the difference between the time given by the satellite and the time in the GPS receiver, it can calculate the distance from the satellite.

How do GPS satellites know their location?
The satellites keep location archived internally in calculated tables. But satellites can get off course over time. To make adjustments, the satellite communicates with ground stations positioned around the globe. Whenever it touches base with the ground stations, the satellite adjusts its internal location tables.

Does a GPS receiver transmit information back to the satellite?
No, they don’t do that. GPS equipped mobile phones will send information but not to the satellite.

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