|
 |
The Global Positioning System (GPS) is a satellite-based navigation system made up of a constallation of
satellites in orbit. GPS satellites orbit the earth twice a day in a very precise orbit and transmit signal
information to earth. These satellites are basically orbiting atomic clocks that constantly transmit timing information.
GPS receivers take this information and use triangulation to calculate the user's exact location.
Essentially, the GPS receiver compares the time a signal was transmitted by a satellite with the time it was received.
The time difference tells the GPS receiver how far away the satellite is.
|
The GPS network is owned and operated by the United States Millitary. These system is primarily used as a precise live positioning
system for the US forces. As a result the signals are deliberatley distorted and errors introduced. The US force's equipment is able
to decode and remove these errors live, giving them millimetre precision. There are other similar systems in use, Russia operates the
Glonass and China have their own constrallation, however, we cannot use this!
With distance measurements from satellites, the receiver can determine the user's position and display it on the
unit's electronic map. A GPS receiver must be locked on to the signal of at least three satellites to calculate a 2D
position (latitude and longitude) and track movement.
With four or more satellites in view, the receiver can determine the user's 3D position (latitude, longitude and altitude).
Once the user's position has been determined, the GPS unit can calculate other information, such as speed, bearing,
track, trip distance, distance to destination, sunrise and sunset time and more.
The GPS network is the one primarily used today. However, the Russian GLONASS (Global Navigation System) has been opened up and manufactureers
are now enabling thier devices to access this network. This gives users a significant boost, as the number of satellites visible at any one time.
This helps users acquire sufficient signal when worknig in difficult environments, such as built up areas with tall buildings or near natural
obsctructions such as trees. Remember, the satellite receiver needs a clear line of sight to the satellite! The GLONASS will be fully operational
by 2009.
The European Union is in the process of launching it's Galileo constallation, this system will use the same transmission format as the USA GPS
network, allowing existing GPS receivers to utilise the new EU satelites. Like the GLONASS, the benefit for users is DOUBLE the number of
satellites visible at any one time, increasing performance in difficult situations as wella s increased accuracy.
As you know, GPS and other SNS can be used for navigation, positioning, determening speed, bearing etc. At CCS we use GPS for various applications (see the GPS/As-Built Surveying section) using various equipment. With modern GPS Survey equipment we are able to survey to centimetre accuracy. The acuracy/precision at which you want to survey at depends on: budget, time and how precise you really need the data. CCS can provide you a solution for any requirement.
Geographical Information Systems (GIS) is a concept of working with data in a spatial context. I.e capturing data that has spatial information (i.e. coordinates that allow you to reference a position) rather than basic attribute inforamtion. managing, manipulating and understanding the data and it's relevacne to the world.
Coupled with this is the unique ability within GIS to attach attribute data to the spatial data, and using either vector
or raster background mapping the user can easily gain a valuable insight as to what is out on the ground without having
to leave the office. Data can be displayed in relative or absolute accuracy; such is the ability of GIS to
allow this manipulation.
It is this versatility of GIS that has made it one of the foremost data management tools used within the utilities sector,
for the displaying and recording of above and below ground assets. GIS not only deals with physical data but also can
readily deal with Socio-economic data sets, combine this together with the physical data collected and you have a
powerful analytical modelling tool.
CCS utilises the latest in GIS software to maximise the information we capture, from modelling datasets to producing hi quality
drawings fro Surveying, we have the ability to take on any task and preduce results in any format the client requires, from AutoCad to MapInfo or ArcGIS or anything in between!
Coupling GIS functionality with GPS ability to accurately map assets and you have an extremely powerful tool available to
the Utility Sector.
The development of GIS Data Collection Equipment with integrated GPS allows real world and real time scenarios to be modelled.
|
|
|
