COMPUFIX IN NAVIGATION - GPS:
COMPUFIX IN NAVIGATION - GIS:
WHAT IS - GPS:
Measuring Distance From Satellite:
We saw in the last section that a position is calculated from distance measurements to at least three satellites.
But how can you measure the distance to something that's floating around in space? We do it by timing how long it takes for a
signal sent from the satellite to arrive at our receiver.
Getting Perfect Timing
If measuring the travel time of a radio signal is the key to GPS, then our stop watches had better be darn good,
because if their timing is off by just a thousandth of a second, at the speed of light, that translates into almost 200
miles of error!
On the satellite side, timing is almost perfect because they have incredibly precise atomic clocks on board.
But what about our receivers here on the ground?
Remember that both the satellite and the receiver need to be able to precisely synchronize their pseudo-random
codes to make the system work. (to review this point click here)
If our receivers needed atomic clocks (which cost upwards of $50K to $100K) GPS would be a lame duck
technology. Nobody could afford it.
Luckily the designers of GPS came up with a brilliant little trick that lets us get by with much less accurate clocks in
our receivers. This trick is one of the key elements of GPS and as an added side benefit it means that every GPS
receiver is essentially an atomic-accuracy clock.
The secret to perfect timing is to make an extra satellite measurement.
That's right, if three perfect measurements can locate a point in 3-dimensional space, then four imperfect
measurements can do the same thing.
This idea is so fundamental to the working of GPS that we have a separate illustrated section that shows how it
works. If you have time, cruise through that
Satellite Positions:
In this tutorial we've been assuming that we know where the GPS satellites are so we can use them as reference points.
But how do we know exactly where they are? After all they're floating around 11,000 miles up in space.
Error Correction:
Up to now we've been treating the calculations that go into GPS very abstractly, as if the whole thing were happening in a
vacuum. But in the real world there are lots of things that can happen to a GPS signal that will make its life less than
mathematically perfect.
To get the most out of the system, a good GPS receiver needs to take a wide variety of possible errors into account. Here's
what they've got to deal with.
In this section you will see how a simple concept can increase the accuracy of GPS to almost unbelievable limits.
Basic GPS is the most accurate radio-based navigation system ever developed. And for many applications it's
plenty accurate. But it's human nature to want MORE!
So some crafty engineers came up with "Differential GPS," a way to correct the various inaccuracies in the GPS
system, pushing its accuracy even farther.
Differential GPS or "DGPS" can yield measurements good to a couple of meters in moving applications and even
better in stationary situations.
That improved accuracy has a profound effect on the importance of GPS as a resource. With it, GPS becomes
more than just a system for navigating boats and planes around the world. It becomes a universal measurement
system capable of positioning things on a very precise scale.
Where to get differential corrections
In the early days of GPS, reference stations were established by private companies who had big projects
demanding high accuracy - groups like surveyors or oil drilling operations. And that is still a very common approach.
You buy a reference receiver and set up a communication link with your roving receivers.
But now there are enough public agencies transmitting corrections that you might be able to get them for free!
The United States Coast Guard and other international agencies are establishing reference stations all over the
place, especially around popular harbors and waterways.
These stations often transmit on the radio beacons that are already in place for radio direction finding (usually in the
300kHz range).
Anyone in the area can receive these corrections and radically improve the accuracy of their GPS measurements.
Most ships already have radios capable of tuning the direction finding beacons, so adding DGPS will be quite easy.
Many new GPS receivers are being designed to accept corrections, and some are even equipped with built-in radio
receivers.
Other ways to work with DGPS
Post Processing DGPS
Not all DGPS applications are created equal. Some don't need the radio link because they don't need precise positioning
immediately.
It's one thing if you're trying to position a drill bit over a particular spot on the ocean floor from a pitching boat, but quite
another if you just want to record the track of a new road for inclusion on a map.
For applications like the later, the roving receiver just needs to record all of its measured positions and the exact time it made
each measurement.
Then later, this data can be merged with corrections recorded at a reference receiver for a final clean-up of the data. So you
don't need the radio link that you have to have in real-time systems.
If you don't have a reference receiver there may be alternative source for corrections in your area. Some academic institutions
are experimenting with the Internet as a way of distributing corrections.
DGPS Advanced Concepts
If you want to know where DGPS might be headed, take a look at your hand, because soon DGPS may be able to resolve
positions that are no farther apart than the width of your little finger.
Imagine the possibilities. Automatic construction equipment could translate CAD drawings into finished roads without any
manual measurements. Self-guided cars could take you across town while you quietly read in the back seat.
To understand how this kind of GPS is being developed you need to understand a little about GPS signals. If two receivers are
fairly close to each other, say within a few hundred kilometers, the signals that reach both of them will have traveled through
virtually the same slice of atmosphere, and so will have virtually the same line.
Putting GPS to work: An Overview
GPS technology has matured into a resource that goes far beyond its original design goals. These days scientists,
sportsmen, farmers, soldiers, pilots, surveyors, hikers, delivery drivers, sailors, dispatchers, lumberjacks,
fire-fighters, and people from many other walks of life are using GPS in ways that make their work more productive,
safer, and sometimes even easier.
In this section you will see a few examples of real-world
Location:
Where am I?"
The first and most obvious application of GPS is the simple determination of a "position" or location. GPS is the first positioning
system to offer highly precise location data for any point on the planet, in any weather. That alone would be enough to qualify
it as a major utility, but the accuracy of GPS and the creativity of its users is pushing it into some surprising realms.
Knowing the precise location of something, or someone, is especially critical when the consequences of inaccurate data are
measured in human terms. For example, when a stranded motorist was lost in a South Dakota blizzard for 2 days, GPS helped
rescuers find her.
GPS is also being applied in Italy to create exact location points for their nationwide geodetic network which will be used for
surveying projects. Once in place it will support the first implementation of a nationally created location survey linked to the
WGS-84 global grid.
Sometimes an exact reference locator is needed for extremely precise scientific work. Just getting to the world's tallest
mountain was tricky, but GPS made measuring the growth of Mt. Everest easy. The data collected strengthened past work, but
also revealed that as the Khumbu glacier moves toward Everest's Base Camp, the mountain itself is getting taller.
Navigation:
Where am I going?"
GPS helps you determine exactly where you are, but sometimes important to know how to get somewhere else. GPS was
originally designed to provide navigation information for ships and planes. So it's no surprise that while this technology is
appropriate for navigating on water, it's also very useful in the air and on the land.
On the Water:
It's interesting that the sea, one of our oldest channels of transportation, has been revolutionized by GPS, the newest
navigation technology. Trimble introduced the world's first GPS receiver for marine navigation in 1985. And as you would
expect, navigating the world's oceans and waterways is more precise than ever.
Today you will find Trimble receivers on vessels the world over, from hardworking fishing boats and long-haul container ships,
to elegant luxury cruise ships and recreational boaters. A New Zealand commercial fishing company uses GPS so they can
return to their best fishing holes without wandering into the wrong waters in the process.
But GPS navigation doesn't end at the shore.
Tracking:
If navigation is the process of getting something from one location to another, then tracking is the process of monitoring it as it
moves along.
Commerce relies on fleets of vehicles to deliver goods and services either across a crowded city or through nationwide
corridors. So, effective fleet management has direct bottom-line implications, such as telling a customer when a package will
arrive, spacing buses for the best scheduled service, directing the nearest ambulance to an accident, or helping tankers avoid
hazards.
GPS used in conjunction with communication links and computers can provide the backbone for systems tailored to
applications in agriculture, mass transit, urban delivery, public safety, and vessel and vehicle tracking. So it's no surprise that
police, ambulance, and fire departments are adopting systems like Trimble's GPS-based AVL (Automatic Vehicle Location)
Manager to pinpoint both the location of the emergency and the location of the nearest response vehicle on a computer map.
With this kind of clear visual picture of the situation, dispatchers can react immediately and confidently.
Mapping:
Where is everything else?"
It's a big world out there, and using GPS to survey and map it precisely saves time and money in this most stringent of all
applications. Today, Trimble GPS makes it possible for a single surveyor to accomplish in a day what used to take weeks with
an entire team. And they can do their work with a higher level of accuracy than ever before.
Trimble pioneered the technology which is now the method of choice for performing control surveys, and the effect on
surveying in general has been considerable. You've seen how GPS pinpoints a position, a route, and a fleet of vehicles.
Mapping is the art and science of using GPS to locate items, then create maps and models of everything in the world. And we
do mean everything. Mountains, rivers, forests and other landforms. Roads, routes, and city streets. Endangered animals,
precious minerals and all sorts of resources. Damage and disasters, trash and archeological treasures. GPS is mapping the
world.
For example, Trimble GPS helped fire fighters respond with speed and efficiency during the 1991 Oakland/Berkeley fire to plot
the extent of the blaze and to evaluate damage. In a less urgent yet equally important situation, the city of Modesto, California
improved their efficiency and job performance by using GPS and mountain bikes to create a precise map of its network of
water resources and utilities.
Timing
When will it all happen?"
Although GPS is well-known for navigation, tracking, and mapping, it's also used to disseminate precise time, time intervals,
and frequency. Time is a powerful commodity, and exact time is more powerful still. Knowing that a group of timed events is
perfectly synchronized is often very important. GPS makes the job of "synchronizing our watches" easy and reliable.
There are three fundamental ways we use time. As a universal marker, time tells us when things happened or when they will.
As a way to synchronize people, events, even other types of signals, time helps keep the world on schedule. And as a way to
tell how long things last, time provides and accurate, unambiguous sense of duration.
GPS satellites carry highly accurate atomic clocks. And in order for the system to work, our GPS receivers here on the ground
synchronize themselves to these clocks. That means that every GPS receiver is, in essence, an atomic accuracy clock.
Astronomers, power companies, computer networks, port & freight companies, communications systems, banks,
gas & oil companies, radio and television stations can benefit from this precise timing. One investment banking firm
uses GPS to guarantee their transactions are recorded simultaneously at all offices around the world. And a major Pacific
Northwest utility company makes sure their power is distributed at just the right time along their 14,797 miles of transmission
lines.
Investment banking firm:
Time Can Buy Money-
One large, international investment banking firm has given new meaning to "synchronize your watches". They've
started using a Trimble Palisade NTP Synchronization Kit to synchronize their computer networks so that
transactions at their London, New York, and Tokyo offices will be recorded simultaneously. To date, the firm has
one Acutime and plans to get more. The GPS receiver serves as the time reference for the transactions
happening on several thousand UNIX host machines and even more PC's. According to their spokesman, the
precision of GPS timing technology provides the firm with: A constant source of market-time information, · An
inarguable reference time source for all transactions, and . The ability to accurately synchronize log files for the
ordering of transactions.
Timing:
High-Energy Transmission with High-Precision GPS Time-
For most of us, the only time we think about the systems that supply our electrical power is when they fail us. Street lights
winking off, the VCR flashing 12:00, or flicking a switch with no result are a few ways we're reminded that there's a fallible
organization responsible for providing our energy. Given the amount of power a power company supplies, the number of
customers they service, and the high-precision timing that the generation and transmission of electricity requires, it's surprising
that power doesn't fail more often.
Increasingly, GPS is becoming the tool that is used to provide that timing. Since 1988, the Bonneville Power Administration in
the U. S. Pacific Northwest has been integrating GPS technology into its operations. As an integral part of any electrical
operations system, timing is the technology on which many of its functions are based. Generation and power transfers
are planned in advance. Utilities coordinate with each other by making adjustments on a GPS timed schedule. Outages for
maintenance are scheduled to ensure that they do not interrupt reliable power delivery. Disturbance records are aligned with
recorded GPS time tags for analysis and comparison with related information. Price varies with demand, so even billing is
based on time. Advanced applications like locating power line faults (short circuits) and real-time phase measurement
require continuous timing with high precision. And bad timing can throw a monkey wrench into all these operations. BPA
administrator, Kenneth Martin puts it all in perspective. "With help from GPS we are finding ways to develop a comprehensive
system that meets the needs of new applications while continuing to serve existing systems. In short, we have found that GPS
is the universal answer for power system timing, meeting all requirements of accuracy, reliability, coverage, and cost."
We saw in the last section that a position is calculated from distance measurements to at least three satellites.
But how can you measure the distance to something that's floating around in space? We do it by timing how long it takes for a
signal sent from the satellite to arrive at our receiver.
Getting Perfect Timing
If measuring the travel time of a radio signal is the key to GPS, then our stop watches had better be darn good,
because if their timing is off by just a thousandth of a second, at the speed of light, that translates into almost 200
miles of error!
On the satellite side, timing is almost perfect because they have incredibly precise atomic clocks on board.
But what about our receivers here on the ground?
Remember that both the satellite and the receiver need to be able to precisely synchronize their pseudo-random
codes to make the system work. (to review this point click here)
If our receivers needed atomic clocks (which cost upwards of $50K to $100K) GPS would be a lame duck
technology. Nobody could afford it.
Luckily the designers of GPS came up with a brilliant little trick that lets us get by with much less accurate clocks in
our receivers. This trick is one of the key elements of GPS and as an added side benefit it means that every GPS
receiver is essentially an atomic-accuracy clock.
The secret to perfect timing is to make an extra satellite measurement.
That's right, if three perfect measurements can locate a point in 3-dimensional space, then four imperfect
measurements can do the same thing.
This idea is so fundamental to the working of GPS that we have a separate illustrated section that shows how it
works. If you have time, cruise through that
Satellite Positions:
In this tutorial we've been assuming that we know where the GPS satellites are so we can use them as reference points.
But how do we know exactly where they are? After all they're floating around 11,000 miles up in space.
Error Correction:
Up to now we've been treating the calculations that go into GPS very abstractly, as if the whole thing were happening in a
vacuum. But in the real world there are lots of things that can happen to a GPS signal that will make its life less than
mathematically perfect.
To get the most out of the system, a good GPS receiver needs to take a wide variety of possible errors into account. Here's
what they've got to deal with.
In this section you will see how a simple concept can increase the accuracy of GPS to almost unbelievable limits.
Basic GPS is the most accurate radio-based navigation system ever developed. And for many applications it's
plenty accurate. But it's human nature to want MORE!
So some crafty engineers came up with "Differential GPS," a way to correct the various inaccuracies in the GPS
system, pushing its accuracy even farther.
Differential GPS or "DGPS" can yield measurements good to a couple of meters in moving applications and even
better in stationary situations.
That improved accuracy has a profound effect on the importance of GPS as a resource. With it, GPS becomes
more than just a system for navigating boats and planes around the world. It becomes a universal measurement
system capable of positioning things on a very precise scale.
Where to get differential corrections
In the early days of GPS, reference stations were established by private companies who had big projects
demanding high accuracy - groups like surveyors or oil drilling operations. And that is still a very common approach.
You buy a reference receiver and set up a communication link with your roving receivers.
But now there are enough public agencies transmitting corrections that you might be able to get them for free!
The United States Coast Guard and other international agencies are establishing reference stations all over the
place, especially around popular harbors and waterways.
These stations often transmit on the radio beacons that are already in place for radio direction finding (usually in the
300kHz range).
Anyone in the area can receive these corrections and radically improve the accuracy of their GPS measurements.
Most ships already have radios capable of tuning the direction finding beacons, so adding DGPS will be quite easy.
Many new GPS receivers are being designed to accept corrections, and some are even equipped with built-in radio
receivers.
Other ways to work with DGPS
Post Processing DGPS
Not all DGPS applications are created equal. Some don't need the radio link because they don't need precise positioning
immediately.
It's one thing if you're trying to position a drill bit over a particular spot on the ocean floor from a pitching boat, but quite
another if you just want to record the track of a new road for inclusion on a map.
For applications like the later, the roving receiver just needs to record all of its measured positions and the exact time it made
each measurement.
Then later, this data can be merged with corrections recorded at a reference receiver for a final clean-up of the data. So you
don't need the radio link that you have to have in real-time systems.
If you don't have a reference receiver there may be alternative source for corrections in your area. Some academic institutions
are experimenting with the Internet as a way of distributing corrections.
DGPS Advanced Concepts
If you want to know where DGPS might be headed, take a look at your hand, because soon DGPS may be able to resolve
positions that are no farther apart than the width of your little finger.
Imagine the possibilities. Automatic construction equipment could translate CAD drawings into finished roads without any
manual measurements. Self-guided cars could take you across town while you quietly read in the back seat.
To understand how this kind of GPS is being developed you need to understand a little about GPS signals. If two receivers are
fairly close to each other, say within a few hundred kilometers, the signals that reach both of them will have traveled through
virtually the same slice of atmosphere, and so will have virtually the same line.
Putting GPS to work: An Overview
GPS technology has matured into a resource that goes far beyond its original design goals. These days scientists,
sportsmen, farmers, soldiers, pilots, surveyors, hikers, delivery drivers, sailors, dispatchers, lumberjacks,
fire-fighters, and people from many other walks of life are using GPS in ways that make their work more productive,
safer, and sometimes even easier.
In this section you will see a few examples of real-world
Location:
Where am I?"
The first and most obvious application of GPS is the simple determination of a "position" or location. GPS is the first positioning
system to offer highly precise location data for any point on the planet, in any weather. That alone would be enough to qualify
it as a major utility, but the accuracy of GPS and the creativity of its users is pushing it into some surprising realms.
Knowing the precise location of something, or someone, is especially critical when the consequences of inaccurate data are
measured in human terms. For example, when a stranded motorist was lost in a South Dakota blizzard for 2 days, GPS helped
rescuers find her.
GPS is also being applied in Italy to create exact location points for their nationwide geodetic network which will be used for
surveying projects. Once in place it will support the first implementation of a nationally created location survey linked to the
WGS-84 global grid.
Sometimes an exact reference locator is needed for extremely precise scientific work. Just getting to the world's tallest
mountain was tricky, but GPS made measuring the growth of Mt. Everest easy. The data collected strengthened past work, but
also revealed that as the Khumbu glacier moves toward Everest's Base Camp, the mountain itself is getting taller.
Navigation:
Where am I going?"
GPS helps you determine exactly where you are, but sometimes important to know how to get somewhere else. GPS was
originally designed to provide navigation information for ships and planes. So it's no surprise that while this technology is
appropriate for navigating on water, it's also very useful in the air and on the land.
On the Water:
It's interesting that the sea, one of our oldest channels of transportation, has been revolutionized by GPS, the newest
navigation technology. Trimble introduced the world's first GPS receiver for marine navigation in 1985. And as you would
expect, navigating the world's oceans and waterways is more precise than ever.
Today you will find Trimble receivers on vessels the world over, from hardworking fishing boats and long-haul container ships,
to elegant luxury cruise ships and recreational boaters. A New Zealand commercial fishing company uses GPS so they can
return to their best fishing holes without wandering into the wrong waters in the process.
But GPS navigation doesn't end at the shore.
Tracking:
If navigation is the process of getting something from one location to another, then tracking is the process of monitoring it as it
moves along.
Commerce relies on fleets of vehicles to deliver goods and services either across a crowded city or through nationwide
corridors. So, effective fleet management has direct bottom-line implications, such as telling a customer when a package will
arrive, spacing buses for the best scheduled service, directing the nearest ambulance to an accident, or helping tankers avoid
hazards.
GPS used in conjunction with communication links and computers can provide the backbone for systems tailored to
applications in agriculture, mass transit, urban delivery, public safety, and vessel and vehicle tracking. So it's no surprise that
police, ambulance, and fire departments are adopting systems like Trimble's GPS-based AVL (Automatic Vehicle Location)
Manager to pinpoint both the location of the emergency and the location of the nearest response vehicle on a computer map.
With this kind of clear visual picture of the situation, dispatchers can react immediately and confidently.
Mapping:
Where is everything else?"
It's a big world out there, and using GPS to survey and map it precisely saves time and money in this most stringent of all
applications. Today, Trimble GPS makes it possible for a single surveyor to accomplish in a day what used to take weeks with
an entire team. And they can do their work with a higher level of accuracy than ever before.
Trimble pioneered the technology which is now the method of choice for performing control surveys, and the effect on
surveying in general has been considerable. You've seen how GPS pinpoints a position, a route, and a fleet of vehicles.
Mapping is the art and science of using GPS to locate items, then create maps and models of everything in the world. And we
do mean everything. Mountains, rivers, forests and other landforms. Roads, routes, and city streets. Endangered animals,
precious minerals and all sorts of resources. Damage and disasters, trash and archeological treasures. GPS is mapping the
world.
For example, Trimble GPS helped fire fighters respond with speed and efficiency during the 1991 Oakland/Berkeley fire to plot
the extent of the blaze and to evaluate damage. In a less urgent yet equally important situation, the city of Modesto, California
improved their efficiency and job performance by using GPS and mountain bikes to create a precise map of its network of
water resources and utilities.
Timing
When will it all happen?"
Although GPS is well-known for navigation, tracking, and mapping, it's also used to disseminate precise time, time intervals,
and frequency. Time is a powerful commodity, and exact time is more powerful still. Knowing that a group of timed events is
perfectly synchronized is often very important. GPS makes the job of "synchronizing our watches" easy and reliable.
There are three fundamental ways we use time. As a universal marker, time tells us when things happened or when they will.
As a way to synchronize people, events, even other types of signals, time helps keep the world on schedule. And as a way to
tell how long things last, time provides and accurate, unambiguous sense of duration.
GPS satellites carry highly accurate atomic clocks. And in order for the system to work, our GPS receivers here on the ground
synchronize themselves to these clocks. That means that every GPS receiver is, in essence, an atomic accuracy clock.
Astronomers, power companies, computer networks, port & freight companies, communications systems, banks,
gas & oil companies, radio and television stations can benefit from this precise timing. One investment banking firm
uses GPS to guarantee their transactions are recorded simultaneously at all offices around the world. And a major Pacific
Northwest utility company makes sure their power is distributed at just the right time along their 14,797 miles of transmission
lines.
Investment banking firm:
Time Can Buy Money-
One large, international investment banking firm has given new meaning to "synchronize your watches". They've
started using a Trimble Palisade NTP Synchronization Kit to synchronize their computer networks so that
transactions at their London, New York, and Tokyo offices will be recorded simultaneously. To date, the firm has
one Acutime and plans to get more. The GPS receiver serves as the time reference for the transactions
happening on several thousand UNIX host machines and even more PC's. According to their spokesman, the
precision of GPS timing technology provides the firm with: A constant source of market-time information, · An
inarguable reference time source for all transactions, and . The ability to accurately synchronize log files for the
ordering of transactions.
Timing:
High-Energy Transmission with High-Precision GPS Time-
For most of us, the only time we think about the systems that supply our electrical power is when they fail us. Street lights
winking off, the VCR flashing 12:00, or flicking a switch with no result are a few ways we're reminded that there's a fallible
organization responsible for providing our energy. Given the amount of power a power company supplies, the number of
customers they service, and the high-precision timing that the generation and transmission of electricity requires, it's surprising
that power doesn't fail more often.
Increasingly, GPS is becoming the tool that is used to provide that timing. Since 1988, the Bonneville Power Administration in
the U. S. Pacific Northwest has been integrating GPS technology into its operations. As an integral part of any electrical
operations system, timing is the technology on which many of its functions are based. Generation and power transfers
are planned in advance. Utilities coordinate with each other by making adjustments on a GPS timed schedule. Outages for
maintenance are scheduled to ensure that they do not interrupt reliable power delivery. Disturbance records are aligned with
recorded GPS time tags for analysis and comparison with related information. Price varies with demand, so even billing is
based on time. Advanced applications like locating power line faults (short circuits) and real-time phase measurement
require continuous timing with high precision. And bad timing can throw a monkey wrench into all these operations. BPA
administrator, Kenneth Martin puts it all in perspective. "With help from GPS we are finding ways to develop a comprehensive
system that meets the needs of new applications while continuing to serve existing systems. In short, we have found that GPS
is the universal answer for power system timing, meeting all requirements of accuracy, reliability, coverage, and cost."
| |||||||||||||||||||||||||||||||||
The Global Positioning System (GPS) is a worldwide radio-navigation system formed from a
constellation of 24 satellites and their ground stations.
GPS uses these "man-made stars" as reference points to calculate positions accurate to a matter of
meters. In fact, with advanced forms of GPS you can make measurements to better than a centimeter!
In a sense it's like giving every square meter on the planet a unique address.
GPS receivers have been miniaturized to just a few integrated circuits and so are becoming very
economical. And that makes the technology accessible to virtually everyone.
These days GPS is finding its way into cars, boats, planes, construction equipment, movie making
gear, farm machinery, even laptop computers.
Soon GPS will become almost as basic as the telephone. Indeed, at Trimble, we think it just may
become a universal utility.
GPS Satellites:
Name: NAVSTAR
Manufacturer: Rockwell International
Altitude: 10,900 nautical miles
Weight: 1900 lbs (in orbit)
Size: 17 ft with solar panels extended
Orbital Period: 12 hours
Orbital Plane: 55 degrees to equitorial plane
Planned Lifespan: 7.5 years
Current constellation: 24 Block II production satellites
Future satellites: 21 Block IIrs developed by Martin Marietta
Ground Stations:
(also known as the "Control Segment")
These stations monitor the GPS satellites, checking both their operational health and their exact position in space.
The master ground station transmits corrections for the satellite's ephemeris constants and clock offsets back to the
satellites themselves. The satellites can then incorporate these updates in the signals they send to GPS receivers.
There are five monitor stations: Hawaii, Ascension Island, Diego Garcia, Kwajalein, and Colorado Springs.
Here's how GPS works in five logical steps:
1. The basis of GPS is "triangulation" from satellites.
2. To "triangulate," a GPS receiver measures distance using the travel time of radio signals.
3. To measure travel time, GPS needs very accurate timing which it achieves with some tricks.
4. Along with distance, you need to know exactly where the satellites are in space. High orbits and careful monitoring are
the secret.
5. Finally you must correct for any delays the signal experiences as it travels through the atmosphere.
We'll explain each of these points in the next five sections of the tutorial. We recommend you follow the tutorial in order.
Remember, science is a step-by-step discipline!
Triangulation???
We're using the word "triangulation" very loosely here because it's a word most people can understand, but purists would not
call what GPS does "triangulation" because no angles are involved. It's really "trilateration
constellation of 24 satellites and their ground stations.
GPS uses these "man-made stars" as reference points to calculate positions accurate to a matter of
meters. In fact, with advanced forms of GPS you can make measurements to better than a centimeter!
In a sense it's like giving every square meter on the planet a unique address.
GPS receivers have been miniaturized to just a few integrated circuits and so are becoming very
economical. And that makes the technology accessible to virtually everyone.
These days GPS is finding its way into cars, boats, planes, construction equipment, movie making
gear, farm machinery, even laptop computers.
Soon GPS will become almost as basic as the telephone. Indeed, at Trimble, we think it just may
become a universal utility.
GPS Satellites:
Name: NAVSTAR
Manufacturer: Rockwell International
Altitude: 10,900 nautical miles
Weight: 1900 lbs (in orbit)
Size: 17 ft with solar panels extended
Orbital Period: 12 hours
Orbital Plane: 55 degrees to equitorial plane
Planned Lifespan: 7.5 years
Current constellation: 24 Block II production satellites
Future satellites: 21 Block IIrs developed by Martin Marietta
Ground Stations:
(also known as the "Control Segment")
These stations monitor the GPS satellites, checking both their operational health and their exact position in space.
The master ground station transmits corrections for the satellite's ephemeris constants and clock offsets back to the
satellites themselves. The satellites can then incorporate these updates in the signals they send to GPS receivers.
There are five monitor stations: Hawaii, Ascension Island, Diego Garcia, Kwajalein, and Colorado Springs.
Here's how GPS works in five logical steps:
1. The basis of GPS is "triangulation" from satellites.
2. To "triangulate," a GPS receiver measures distance using the travel time of radio signals.
3. To measure travel time, GPS needs very accurate timing which it achieves with some tricks.
4. Along with distance, you need to know exactly where the satellites are in space. High orbits and careful monitoring are
the secret.
5. Finally you must correct for any delays the signal experiences as it travels through the atmosphere.
We'll explain each of these points in the next five sections of the tutorial. We recommend you follow the tutorial in order.
Remember, science is a step-by-step discipline!
Triangulation???
We're using the word "triangulation" very loosely here because it's a word most people can understand, but purists would not
call what GPS does "triangulation" because no angles are involved. It's really "trilateration
Glossary
The Ideas Behind the Jargon
Anywhere fix
The ability of a receiver to start position calculations without being given an approximate location and approximate time.
Bandwidth
The range of frequencies in a signal.
C/A code
The standard (Course/Acquisition) GPS code. A sequence of 1023 pseudo-random, binary, biphase modulations on the
GPS carrier at a chip rate of 1.023 MHz. Also known as the "civilian code."
Carrier
A signal that can be varied from a known reference by modulation.
Carrier-aided tracking
A signal processing strategy that uses the GPS carrier signal to achieve an exact lock on the pseudo random code.
Carrier frequency
The frequency of the unmodulated fundamental output of a radio transmitter.
Carrier phase GPS
GPS measurements based on the L1 or L2 carrier signal.
Channel
A channel of a GPS receiver consists of the circuitry necessary to receive the signal from a single GPS satellite.
Chip
The transition time for individual bits in the pseudo-random sequence. Also, an integrated circuit. Also a snack food. Also a
betting marker.
Clock bias
The difference between the clock's indicated time and true universal time.
Code phase GPS
GPS measurements based on the pseudo random code (C/A or P) as opposed to the carrier of that code.
Control segment
A world-wide network of GPS monitor and control stations that ensure the accuracy of satellite positions and their clocks.
Cycle slip
A discontinuity in the measured carrier beat phase resulting from a temporary loss of lock in the carrier tracking loop of a
GPS receiver
Data message
A message included in the GPS signal which reports the satellite's location, clock corrections and health. Included is rough
information on the other satellites in the constellation.
Differential positioning
Accurate measurement of the relative positions of two receivers tracking the same GPS signals.
Dilution of Precision
The multiplicative factor that modifies ranging error. It is caused solely by the geometry between the user and his set of
satellites. Known as DOP or GDOP
Dithering
The introduction of digital noise. This is the process the DoD uses to add inaccuracy to GPS signals to induce Selective
Availability.
Doppler-aiding
A signal processing strategy that uses a measured doppler shift to help the receiver smoothly track the GPS signal. Allows
more precise velocity and position measurement.
Doppler shift
The apparent change in the frequency of a signal caused by the relative motion of the transmitter and receiver.
Ephemeris
The predictions of current satellite position that are transmitted to the user in the data message.
Fast switching channel
A single channel which rapidly samples a number of satellite ranges. "Fast" means that the switching time is sufficiently fast
(2 to 5 milliseconds) to recover the data message.
Frequency band
A particular range of frequencies.
Frequency spectrum
The distribution of signal amplitudes as a function of frequency
Geometric Dilution of Precision (GDOP) See Dilution of Precision.
Hardover word
The word in the GPS message that contains synchronization information for the transfer of tracking from the C/A to P code.
Ionosphere
The band of charged particles 80 to 120 miles above the Earth's surface.
Ionospheric refraction
The change in the propagation speed of a signal as it passes through the ionosphere.
L-band
The group of radio frequencies extending from 390 MHz to 1550 MHz. The GPS carrier frequencies (1227.6 MHz and
1575.42 MHz) are in the L band.
Multipath error
Errors caused by the interference of a signal that has reached the receiver antenna by two or more different paths. Usually
caused by one path being bounced or reflected.
Multi-channel receiver
A GPS receiver that can simultaneously track more than one satellite signal.
Multiplexing channel
A channel of a GPS receiver that can be sequenced through a number of satellite signals.
P-code
The Precise code. A very long sequence of pseudo random binary biphase modulations on the GPS carrier at a chip rate of
10.23 MHz which repeats about every 267 days. Each one week segment of this code is unique to one GPS satellite and is
reset each week.
Precise Positioning Service (PPS)
The most accurate dynamic positioning possible with standard GPS, based on the dual frequency P-code and no SA.
Pseudolite
A ground-based differential GPS receiver which transmits a signal like that of an actual GPS satellite, and can be used for
ranging.
Pseudo random code
A signal with random noise-like properties. It is a very complicated but repeating pattern of 1's and O's.
Pseudorange
A distance measurement based on the correlation of a satellite transmitted code and the local receiver's reference code,
that has not been corrected for errors in synchronization between the transmitter's clock and the receiver's clock.
Satellite constellation
The arrangement in space of a set of satellites.
Selective Availability (SA)
A policy adopted by the Department of Defense to introduce some intentional clock noise into the GPS satellite signals
thereby degrading their accuracy for civilian users. This policy was discontinued as of May 1, 2000 and now SA is turned off
Slow switching channel
A sequencing GPS receiver channel that switches too slowly to allow the continuous recovery of the data message.
Space segment
The part of the whole GPS system that is in space, i.e. the satellites.
Spread spectrum
A system in which the transmitted signal is spread over a frequency band much wider than the minimum bandwidth needed
to transmit the information being sent. This is done by modulating with a pseudo random code, for GPS.
Standard Positioning Service (SPS)
The normal civilian positioning accuracy obtained by using the single frequency C/A code.
Static positioning
Location determination when the receiver's antenna is presumed to be stationary on the Earth. This allows the use of
various averaging techniques that improve accuracy by factors of over 1000.
User interface
The way a receiver conveys information to the person using it. The controls and displays.
User segment
The part of the whole GPS system that includes the receivers of GPS signals.
The Ideas Behind the Jargon
Anywhere fix
The ability of a receiver to start position calculations without being given an approximate location and approximate time.
Bandwidth
The range of frequencies in a signal.
C/A code
The standard (Course/Acquisition) GPS code. A sequence of 1023 pseudo-random, binary, biphase modulations on the
GPS carrier at a chip rate of 1.023 MHz. Also known as the "civilian code."
Carrier
A signal that can be varied from a known reference by modulation.
Carrier-aided tracking
A signal processing strategy that uses the GPS carrier signal to achieve an exact lock on the pseudo random code.
Carrier frequency
The frequency of the unmodulated fundamental output of a radio transmitter.
Carrier phase GPS
GPS measurements based on the L1 or L2 carrier signal.
Channel
A channel of a GPS receiver consists of the circuitry necessary to receive the signal from a single GPS satellite.
Chip
The transition time for individual bits in the pseudo-random sequence. Also, an integrated circuit. Also a snack food. Also a
betting marker.
Clock bias
The difference between the clock's indicated time and true universal time.
Code phase GPS
GPS measurements based on the pseudo random code (C/A or P) as opposed to the carrier of that code.
Control segment
A world-wide network of GPS monitor and control stations that ensure the accuracy of satellite positions and their clocks.
Cycle slip
A discontinuity in the measured carrier beat phase resulting from a temporary loss of lock in the carrier tracking loop of a
GPS receiver
Data message
A message included in the GPS signal which reports the satellite's location, clock corrections and health. Included is rough
information on the other satellites in the constellation.
Differential positioning
Accurate measurement of the relative positions of two receivers tracking the same GPS signals.
Dilution of Precision
The multiplicative factor that modifies ranging error. It is caused solely by the geometry between the user and his set of
satellites. Known as DOP or GDOP
Dithering
The introduction of digital noise. This is the process the DoD uses to add inaccuracy to GPS signals to induce Selective
Availability.
Doppler-aiding
A signal processing strategy that uses a measured doppler shift to help the receiver smoothly track the GPS signal. Allows
more precise velocity and position measurement.
Doppler shift
The apparent change in the frequency of a signal caused by the relative motion of the transmitter and receiver.
Ephemeris
The predictions of current satellite position that are transmitted to the user in the data message.
Fast switching channel
A single channel which rapidly samples a number of satellite ranges. "Fast" means that the switching time is sufficiently fast
(2 to 5 milliseconds) to recover the data message.
Frequency band
A particular range of frequencies.
Frequency spectrum
The distribution of signal amplitudes as a function of frequency
Geometric Dilution of Precision (GDOP) See Dilution of Precision.
Hardover word
The word in the GPS message that contains synchronization information for the transfer of tracking from the C/A to P code.
Ionosphere
The band of charged particles 80 to 120 miles above the Earth's surface.
Ionospheric refraction
The change in the propagation speed of a signal as it passes through the ionosphere.
L-band
The group of radio frequencies extending from 390 MHz to 1550 MHz. The GPS carrier frequencies (1227.6 MHz and
1575.42 MHz) are in the L band.
Multipath error
Errors caused by the interference of a signal that has reached the receiver antenna by two or more different paths. Usually
caused by one path being bounced or reflected.
Multi-channel receiver
A GPS receiver that can simultaneously track more than one satellite signal.
Multiplexing channel
A channel of a GPS receiver that can be sequenced through a number of satellite signals.
P-code
The Precise code. A very long sequence of pseudo random binary biphase modulations on the GPS carrier at a chip rate of
10.23 MHz which repeats about every 267 days. Each one week segment of this code is unique to one GPS satellite and is
reset each week.
Precise Positioning Service (PPS)
The most accurate dynamic positioning possible with standard GPS, based on the dual frequency P-code and no SA.
Pseudolite
A ground-based differential GPS receiver which transmits a signal like that of an actual GPS satellite, and can be used for
ranging.
Pseudo random code
A signal with random noise-like properties. It is a very complicated but repeating pattern of 1's and O's.
Pseudorange
A distance measurement based on the correlation of a satellite transmitted code and the local receiver's reference code,
that has not been corrected for errors in synchronization between the transmitter's clock and the receiver's clock.
Satellite constellation
The arrangement in space of a set of satellites.
Selective Availability (SA)
A policy adopted by the Department of Defense to introduce some intentional clock noise into the GPS satellite signals
thereby degrading their accuracy for civilian users. This policy was discontinued as of May 1, 2000 and now SA is turned off
Slow switching channel
A sequencing GPS receiver channel that switches too slowly to allow the continuous recovery of the data message.
Space segment
The part of the whole GPS system that is in space, i.e. the satellites.
Spread spectrum
A system in which the transmitted signal is spread over a frequency band much wider than the minimum bandwidth needed
to transmit the information being sent. This is done by modulating with a pseudo random code, for GPS.
Standard Positioning Service (SPS)
The normal civilian positioning accuracy obtained by using the single frequency C/A code.
Static positioning
Location determination when the receiver's antenna is presumed to be stationary on the Earth. This allows the use of
various averaging techniques that improve accuracy by factors of over 1000.
User interface
The way a receiver conveys information to the person using it. The controls and displays.
User segment
The part of the whole GPS system that includes the receivers of GPS signals.
Vehicle Tracking:
Vehicle Tracking & Mobile
Resource ManagementTrimble offers a variety of solutions to meet your vehicle tracking/fleet management needs. Whether
you are a fleet manager looking for a turnkey vehicle tracking solution, or a system integrator needing proven hardware and
software building blocks for your custom AVL system, there's a Trimble solution for you today.For fleet owners and
operatorsTrimble's Telvisant Fleet Management Services provide a complete, ready solution that will improve your vision and
control of your fleet's performance.For system integratorsTrimble offers a variety of products for System Integrators.
Products include:
o GPS/AVL subsystems for Public Safety
o In-vehicle hardware for use in your own vehicle tracking systems
o Tools for integrating CompufixTelvi software solutions into a third-party dispatch, ERP, or other existing system.
Fleet Management:
CompufixTelvi Fleet Management Services
CompufixTelvi Services provide everything you need for efficient and cost-effective management of your fleet operations. You
provide a computer and an Internet connection; we provide the rest. Your subscription to CompufixTelvi Services brings you
position and status reports for each vehicle at intervals that are right for your operation and budget. And powerful reporting
capabilities let you analyze your fleet's performance for critical, informed decision-making.
To get started, select a plan that's right for you:
CompufixTelvi Dispatch Plans
Easy to use plans that provide real-time fleet data for dispatch applications.
CompufixTelvi SuperVision Plans
Easy to use plans that provide a clear vision of fleet activity
CompufixTelvi Ready Mix Industry Plan
An easy to use plan specially tailored to ready mix fleet operations.
DriveSafe Plans NEW!
Reports on how your drivers are operating your ready mixed concrete trucks. Available standalone or with the Ready Mix
Industry Plan.
Technology:
The performance of the CompufixTelvi Mobile Resource Management (MRM) System is based on advanced technology
developed by Compufix Intercom USA. Compufix Intercom USA have earned a reputation for technological innovation and
quality over its combine 20 years of leading the commercial GPS industry. The technology advantages of the CompufixTelvi
MRM System are centered in:
· The CompufixTelviMRM Platform
· CompufixTelvi System Elements
The CompufixTelvi Mobile Resource Management Platform is the foundation of the Telvisant MRM System. It is the link
between your fleet and your enterprise. Physically housed in the CompufixTelvi Data Center, the platform receives,
processes and stores the fleet reports and enables near real-time access to the data by your personnel over the
Internet.
The CompufixTelvi System Elements form the other parts of the MRM System. They include:
· In-vehicle hardware
· Wireless services
· Hosted applications
· A powerful database
System Integration:
Improving your system with Compufix Intercom USA capability, Compufix Intercom USA offers a variety of ways to help you
develop a system that will improve the operation of your customer's fleet management system—or your own. Whether you
need hardware or software building blocks or a complete front-end data collection and reporting capability, there's
a proven Compufix Intercom USA capability that can make your job easier and your system's performance better.
AVL Subsystems for Public Safety:
in-vehicle hardware and base-station software building blocks, proven in numerous public safety emergency response
networks around the world
In-vehicle hardware for tracking systems:
Compact positioning, communications, and messaging units for a variety of fleet applications
CompufixTelvi Developer Program:
Tools and support needed to bring vehicle data into your software applications.
In-vehicle hardware and base-station software solutions
For commercial fleets around the world, Compufix offers premier hardware and software products for your system
development needs. Your fleet can benefit from Compufix Intercom USA's experience in providing in-vehicle hardware and base
station software and developer tools for tracking systems solutions. Compufix offers a range of messaging, mapping, and
communications options that enable developers and system integrators to support fleet management and security
solutions for end users.
The following products are ideal for commercial fleet operations:
Choose the GSM, CrossCheck AMPS or GPS 450 as your mobile GPS receiver, and FleetVision® as your base
station software.
CrossCheck is a family of products which integrates GPS, wireless communication and computing technologies into a single,
low-cost mobile positioning and communications unit. Each includes the IQEvent Engine® firmware, which supports automated
monitoring and reporting of vehicle activity and status.
450/455 is family of products with a tightly integrated communications interface. When combined with a communications
transceiver, the system's state-of-the-art, 8-channel GPS receiver reports vehicle position, speed, time, and status from
anywhere, over radio or cellular communications networks
For information on features, installation, troubleshooting, etc:
Mobile Units:
Base-Station Software:
Base-Station Software
CompufixTelvi Developer Program:
COmpufixTelvi Developer Program is designed to provide Developers with the technology to address the needs of their
markets.
If your company provides products and services for applications that can be enhanced by a mobile resource management
interface, join the CompufixTelvi Developer Program and transition your company into a provider of one of the most powerful
MRM solutions available.
The CompufixTelvi Developer Program provides partners with the tools and support needed to enhance existing applications
with location-specific functionality. Compufix's XML-based Software Developer's Kit (SDK) enables you to interface your
existing applications to the CompufixTelvi platform, adding the benefit of wireless connectivity, mapping, messaging, work
order management and reporting to your solution.
Mobil GIS:
Work Flow Mobil GIS:
Related Products
Asset Management :
Assets take many forms. They can be mobile, such as:
· fleets of vehicles—taxis, trucks, emergency response vehicles, . . .
· railroad cars, boats, airplanes , Containers
· packages or other items being shipped or stored
Or the assets can be fixed in position, such as:
· utility hardware—telephone poles, fire hydrants, electric or radio towers, pipelines, . . .
· natural resources—land, trees, bodies of water, mineral deposits . . .
· public building inventories
Whatever the asset, you need to know its current location, status or condition, and other information about it in order to
effectively manage its contribution to your business or organization's performance. The more accurate and up-to-date
your information, the better the decisions you can make. Where is a specific vehicle and what is its status? Which park
benches need painting? Where is my shipment? Where is my Container?
Compufix Intercom USA provides premier tools for managing these and many other types of assets
· For fixed assets, our solid foundation in GIS data collection products continues to make Compufix Intercom USA the
choice for data collection and utilization systems. These systems help managers accurately and easily digitize asset locations
and conditions and use that data for relocation and maintenance of those assets
·
For mobile assets, Compufix Intercom USA offers a variety of solutions to meet your vehicle tracking/fleet management
needs. Whether you are a fleet manager looking for a turnkey vehicle tracking solution, or a system integrator needing
proven hardware and software building blocks for your custom AVL system, there's a Compufix Intercom USA solution for
you today.
Urban & Municipal Planning:
Related Products
Reference StationsReference station file management
Vehicle Tracking & Mobile
Resource ManagementTrimble offers a variety of solutions to meet your vehicle tracking/fleet management needs. Whether
you are a fleet manager looking for a turnkey vehicle tracking solution, or a system integrator needing proven hardware and
software building blocks for your custom AVL system, there's a Trimble solution for you today.For fleet owners and
operatorsTrimble's Telvisant Fleet Management Services provide a complete, ready solution that will improve your vision and
control of your fleet's performance.For system integratorsTrimble offers a variety of products for System Integrators.
Products include:
o GPS/AVL subsystems for Public Safety
o In-vehicle hardware for use in your own vehicle tracking systems
o Tools for integrating CompufixTelvi software solutions into a third-party dispatch, ERP, or other existing system.
Fleet Management:
CompufixTelvi Fleet Management Services
CompufixTelvi Services provide everything you need for efficient and cost-effective management of your fleet operations. You
provide a computer and an Internet connection; we provide the rest. Your subscription to CompufixTelvi Services brings you
position and status reports for each vehicle at intervals that are right for your operation and budget. And powerful reporting
capabilities let you analyze your fleet's performance for critical, informed decision-making.
To get started, select a plan that's right for you:
CompufixTelvi Dispatch Plans
Easy to use plans that provide real-time fleet data for dispatch applications.
CompufixTelvi SuperVision Plans
Easy to use plans that provide a clear vision of fleet activity
CompufixTelvi Ready Mix Industry Plan
An easy to use plan specially tailored to ready mix fleet operations.
DriveSafe Plans NEW!
Reports on how your drivers are operating your ready mixed concrete trucks. Available standalone or with the Ready Mix
Industry Plan.
Technology:
The performance of the CompufixTelvi Mobile Resource Management (MRM) System is based on advanced technology
developed by Compufix Intercom USA. Compufix Intercom USA have earned a reputation for technological innovation and
quality over its combine 20 years of leading the commercial GPS industry. The technology advantages of the CompufixTelvi
MRM System are centered in:
· The CompufixTelviMRM Platform
· CompufixTelvi System Elements
The CompufixTelvi Mobile Resource Management Platform is the foundation of the Telvisant MRM System. It is the link
between your fleet and your enterprise. Physically housed in the CompufixTelvi Data Center, the platform receives,
processes and stores the fleet reports and enables near real-time access to the data by your personnel over the
Internet.
The CompufixTelvi System Elements form the other parts of the MRM System. They include:
· In-vehicle hardware
· Wireless services
· Hosted applications
· A powerful database
System Integration:
Improving your system with Compufix Intercom USA capability, Compufix Intercom USA offers a variety of ways to help you
develop a system that will improve the operation of your customer's fleet management system—or your own. Whether you
need hardware or software building blocks or a complete front-end data collection and reporting capability, there's
a proven Compufix Intercom USA capability that can make your job easier and your system's performance better.
AVL Subsystems for Public Safety:
in-vehicle hardware and base-station software building blocks, proven in numerous public safety emergency response
networks around the world
In-vehicle hardware for tracking systems:
Compact positioning, communications, and messaging units for a variety of fleet applications
CompufixTelvi Developer Program:
Tools and support needed to bring vehicle data into your software applications.
In-vehicle hardware and base-station software solutions
For commercial fleets around the world, Compufix offers premier hardware and software products for your system
development needs. Your fleet can benefit from Compufix Intercom USA's experience in providing in-vehicle hardware and base
station software and developer tools for tracking systems solutions. Compufix offers a range of messaging, mapping, and
communications options that enable developers and system integrators to support fleet management and security
solutions for end users.
The following products are ideal for commercial fleet operations:
Choose the GSM, CrossCheck AMPS or GPS 450 as your mobile GPS receiver, and FleetVision® as your base
station software.
CrossCheck is a family of products which integrates GPS, wireless communication and computing technologies into a single,
low-cost mobile positioning and communications unit. Each includes the IQEvent Engine® firmware, which supports automated
monitoring and reporting of vehicle activity and status.
450/455 is family of products with a tightly integrated communications interface. When combined with a communications
transceiver, the system's state-of-the-art, 8-channel GPS receiver reports vehicle position, speed, time, and status from
anywhere, over radio or cellular communications networks
For information on features, installation, troubleshooting, etc:
Mobile Units:
Base-Station Software:
Base-Station Software
CompufixTelvi Developer Program:
COmpufixTelvi Developer Program is designed to provide Developers with the technology to address the needs of their
markets.
If your company provides products and services for applications that can be enhanced by a mobile resource management
interface, join the CompufixTelvi Developer Program and transition your company into a provider of one of the most powerful
MRM solutions available.
The CompufixTelvi Developer Program provides partners with the tools and support needed to enhance existing applications
with location-specific functionality. Compufix's XML-based Software Developer's Kit (SDK) enables you to interface your
existing applications to the CompufixTelvi platform, adding the benefit of wireless connectivity, mapping, messaging, work
order management and reporting to your solution.
Mobil GIS:
Work Flow Mobil GIS:
Related Products
Asset Management :
Assets take many forms. They can be mobile, such as:
· fleets of vehicles—taxis, trucks, emergency response vehicles, . . .
· railroad cars, boats, airplanes , Containers
· packages or other items being shipped or stored
Or the assets can be fixed in position, such as:
· utility hardware—telephone poles, fire hydrants, electric or radio towers, pipelines, . . .
· natural resources—land, trees, bodies of water, mineral deposits . . .
· public building inventories
Whatever the asset, you need to know its current location, status or condition, and other information about it in order to
effectively manage its contribution to your business or organization's performance. The more accurate and up-to-date
your information, the better the decisions you can make. Where is a specific vehicle and what is its status? Which park
benches need painting? Where is my shipment? Where is my Container?
Compufix Intercom USA provides premier tools for managing these and many other types of assets
· For fixed assets, our solid foundation in GIS data collection products continues to make Compufix Intercom USA the
choice for data collection and utilization systems. These systems help managers accurately and easily digitize asset locations
and conditions and use that data for relocation and maintenance of those assets
·
For mobile assets, Compufix Intercom USA offers a variety of solutions to meet your vehicle tracking/fleet management
needs. Whether you are a fleet manager looking for a turnkey vehicle tracking solution, or a system integrator needing
proven hardware and software building blocks for your custom AVL system, there's a Compufix Intercom USA solution for
you today.
Urban & Municipal Planning:
Related Products
Reference StationsReference station file management
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