Cell Phone GPS Primer

bobbyjones| April 12, 2010 | No Comments

Soon GPS will become almost as basic as the telephone, or more likely included with every smartphone.  GPS can determine locations accurate to a matter of just a few meters.  In fact, incredibly with advanced forms of GPS it is possible to achieve measurements to less than a centimeter!

It’s just like giving every square meter on the planet a unique address.  GPS receivers have become very affordable through miniaturization to just a few integrated circuits.  These days GPS is incorporated into cars, boats, planes, construction equipment, movie making gear, farm machinery, laptop computers and especially  cell phones.

Tracking mobile phones is a popular topic getting a lot of interest.   A lot of the discussion surrounding GPS tracking, mobile GPS and cell phone tracking software applications would be more meaningful with a GPS Satellite primer and glossary.

GPS is an acronym for Global Positioning System.   GPS satellites broadcast signals from space that GPS receivers use to provide three-dimensional location (latitude, longitude, and altitude) plus precise time.  The GPS system is made up of 3 primary segments: Space Segment, Control Segment and User Segment. 

The GPS Space Segment made up of twenty-four  to thirty-two satellites that orbit the earth at a height of about 12,000 miles.  These satellites are referred to as the GPS Constellation, and they make an orbit once every 12 hours.  They are not geosynchronous, they travel at over 7,000 mph.  They are solar powered but have battery backup for when they are on the dark side of the earth. They are positioned so that 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 have a lifetime of about 10 years until all their fuel is exhausted. 

GPS Satellites are not communications satellites.   Geostationary or communications satellites are at a much higher orbit of about 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 best location to place a communications satellite.   The earth rotates at about 1,000 miles an hour, and because of their high earth orbit the geostationary satellites need to travel at about 7,000 mph to keep position.  This is just about the same speed as GPS satellites, but since communications 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 make sure the satellites are functioning to specification and the data they beam down to earth is accurate. 

The GPS User Segment consists of of GPS receivers  taking the shape of smartphones 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 function.  

GPS receivers compute 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 fundamental difference between handset GPS Tracking and GPS Navigation.  GPS phone tracking is normally related to someone maintaining records of either real-time or historical cell phone  location, while Navigation deals with the mobile phone  user determining how to get from point A to point B.  Neither use works without some kind of third-party software application.

A really great software package that features  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. 

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 FAQ

Why does GPS receiver only work outside?
GPS satellites are positioned in their orbits such that from any location on earth there are a minimum four satellites visibile at all times. Even though the satellites use radio signals, they needs a clear of site to the receiver. Once the GPS satellite drops behind the horizon, or a building, or even heavy cloud cover, the radio signal may not reach the receiver.  

What do the satellites do?
Each satellite is broadcasting the time. Both the satellite and the GPS receiver use atomic clocks for extreme accuracy.  By measuring 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 does the GPS satellite know where it is?
The satellites keep position archived internally in calculated tables. But satellites can get off course over time. To correct this, the satellite communicates with fixed reference stations positioned around the world. Each time it touches base with the ground stations, the satellite adjusts its internal location tables.

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

Visit this link for more information regarding the latest software for  GPS Tracking

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