What can GPS tracker do for you ?

What can GPS tracker do for you? The PLGR was the GPS receiver most widely used by the U.S. military. It is a five-channel, L1-only receiver, with a typical time to first fix of over a minute, and a cost of about $2,000. The PLGR receives encrypted P-code military signals, is waterproof, weighs three pounds and is far more robust than any modern mobile phone. But many of those mobile phones today have GPS tracker, which can compute a position within a second and acquire satellites at signal levels 100 times lower than the PLGR, and adds less than $5 to the cost of the phone.  Nowadays, GPS Made In China enabled phones are widely available and are viable options for a dedicated handheld or an in-car GPS. These requirements are what drove the development of GPS tracker. Assisted GPS (GPS tracker) improves on standard GPS performance by providing information, through an alternative communication channel, that the GPS receiver would ordinarily have received from the satellites themselves.

More than 35 years have passed since some of us were fortunate enough to play a role in the design of GPS. Predecessor systems and designs, such as Transit, Timation, 621B, DNSS, and atomic clocks provided some of its foundations. Considered at first by some as a useless adventure of some technologists with little knowledge of real navigation, GPS has now become a household word and has many millions of users, mostly civilian, in aircraft, ships, surveying, construction, and most of all, cell phones and automobiles ( such as GPS Tracker China, mirror GPS ). Assisted GPS (GPS tracker) is one of the major contributors to the widespread use of GPS, especially for cell phones and other handheld units. GPS tracker integrates GPS and communications, especially wireless and utilizes GPS chips with added low-cost processing power and many thousands of correlators. GPS satellites are limited in the amount of power they can provide to users on the ground many thousands of miles away. GPS tracker provides important information, by means of these separate wireless communications channels, to substantially improve the processing power of the GPS receiver, so that they can operate successfully in disadvantaged locations and circumstances where buildings, trees, hills may partially degrade the GPS signals.

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GPS was originally designed to guide bombs, aircraft, soldiers, and sailors. In all cases, the Personal GPS Homing Device was expected to be outside with a relatively clear view of the sky. The system was designed to require a start-up time of approximately 1 min, and after that it would operate continuously. Today GPS is used for many more civilian than military purposes. Counterintuitively, the system demands of these civilian applications far exceed those seen before. GPS is now expected to work almost anywhere, even, sometimes, indoors; push-to-fix applications have emerged where a single position is expected almost instantly; and all of this must be delivered in a way that adds little or no cost, size, or power consumption to the host device.  You probably recognize the ways that your car’s GPS rearview mirror and telematics system track you for your own good. Their tracking gives you directions. It means you will be found in the event of a crash.
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About GPS Surveying Techniques

If a static GPS control survey is carefully planned, it usually progresses smoothly. The technology has virtually conquered two stumbling blocks that have defeated the plans of conventional surveyors for generations. Inclement weather does not disrupt GPS observations, and a lack of intervisibility between stations is of no concern whatsoever, at least in postprocessed GPS. Still, electronic tracking devices is far from so independent of conditions in the sky and on the ground that the process of designing a survey can now be reduced to points-per-day formulas, as some would like. Even with falling costs, the initial investment in Personal GPS Homing Device remains large by most surveyors’ standards. However, there is seldom anything more expensive in a GPS project than a surprise.

New Design Criteria
These upgrades in accuracy standards not only accommodate control by static Personal GPS Tracker; they also have cast survey design into a new light for many surveyors. Nevertheless, it is not correct to say that every job suddenly requires the highest achievable accuracy, nor is it correct to say that every asset tracking device survey now demands an elaborate design. In some situations, a crew of two, or even one surveyor on-site may carry a GPS survey from start to finish with no more planning than minute-to-minute decisions can provide even though the basis and the content of those decisions may be quite different from those made in a conventional survey. In areas that are not heavily treed and generally free of overhead obstructions, the now-lower C group of accuracy may be possible without a prior design of any significance. But while it is certainly unlikely that a survey of photocontrol or work on a cleared construction site would present overhead obstructions problems comparable with a static GPS control survey in the Rocky Mountains, even such open work may demand preliminary attention. For example, just the location of appropriate vertical and horizontal control stations or obtaining permits for access across privately owned property or government installations can be critical to the success of the work.
The Lay of the Land
An initial visit to the site of the survey is not always possible. Today, online mapping browsers are making virtual site evaluation possible as well. Topography as it affects the line of sight between stations is of no concern on a static GPS Cell Phone Tracking Device project, but its influence on transportation from station to station is a primary consideration. Perhaps some areas are only accessible by helicopter or other special vehicle. Initial inquiries can be made. Roads may be excellent in one area of the project and poor in another. The general density of vegetation, buildings, or fences may open general questions of overhead obstruction or multipath. The pattern of land ownership relative to the location of project points may raise or lower the level of concern about obtaining permission to cross property.
Maps, both digital and hard-copy, are particularly valuable resources for preparing a static GPS survey design. Local government and private sources can sometimes provide appropriate mapping, or it maybe available online. Other mapping that may be helpful is available from various government agencies: for example, the U.S. Forest Service in the Department of Agriculture; the Department of Interior’s Bureau of Land Management, Bureau of Reclamation, and National Park Service; the U.S. Fish and Wildlife Service in the Department of Commerce; and the Federal Highway Administration in the Department of Transportation are just a few of them. Even county and city maps should be considered since they can sometimes provide the most timely information available. Depending on the scope of the survey, various scales and types of maps can be useful. For example, a GPS survey plan may begin with the plotting of all potential control and project points on a map of the area. However, one vital element of the design is not available from any of these maps: the National Spatial Reference System (NSRS) stations.
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High Sensitivity – GPS Tracking Devices

We are now ready to exploit all this knowledge to study the design of A-GPS receivers that have much greater sensitivity than standard GPS Device China . If you are designing a high-sensitivity receiver, then it is essential to understand the relationship of these signals to each other and the effects of each of the receiver components on the signal. Once you understand the processing gain of each part of the receiver, then it is a small step to understand how to increase that gain and thus increase the sensitivity of the receiver. However, even if you are not designing a receiver, it is still important to understand the relationship of the signal strength at the antenna to the correlation response. This is because the measure of a high sensitivity receiver is its ability to acquire and track weak signals. The only way of knowing how weak the signals actually are, in practice, is for the receiver to tell you, and the way the receiver knows is by back-calculating the signal strength from the measured height of the correlation response. The receiver has no way of directly measuring the signal at the antenna or in the front end. Only after the receiver has created the correlation response does it have a measure of what the signal at the antenna was. Moreover, there is no such thing as a separate signal-strength meter that you can plug into a GPS antenna to measure the strength of the signals. The GPS receiver is the signal strength meter.

 GPS Tracking Devices

The problem of building high-sensitivity receivers and measuring how good they are is analogous to building a fast car and measuring how fast it is going with the speedometer. The car maker also builds the speedometer. The speedometer actually measures how fast the wheels are turning. Only if the manufacturer correctly calibrates the rotation rate of the wheels to the diameter of the inflated tire will the speed reading actually be correct. What about radar guns, or other external measures? The Vehicle GPS Tracking Device equivalent of the radar gun is the RF simulator, which can generate RF signals with known signal strength, and these can be used to calibrate the receiver in an analogous way to calibrating a car’s speedometer.
Even with a simulator, however, things are not as simple as they seem. If you are evaluating or integrating high-sensitivity receivers, then you need to be aware of details such as thermal noise sources. A GPS Device Manufacturers In China  generates thermal noise at room temperature, while the actual GPS satellites are in space where the temperature can be almost at absolute zero (0K, or –273°C). The simulator’s thermal noise must be correctly accounted for. If you are not evaluating or integrating a receiver, but simply using it in practice, then you are like the car buyer who must trust that the speedometer is telling the truth. In all cases, it is certainly useful to understand what goes on between the antenna and the correlation response. When A-GPS is combined with massive parallel correlation, processing gain can be as much as 30 dB (1,000 times) more than for a standard China GPS Device . This allows the high-sensitivity receiver to acquire signals and work in many places where GPS was not previously possible, even, sometimes, indoors.
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Basic Knowledge of GPS Tracking System

Types of GPS Tracking System :GPS tracking system can work in various ways, such as passive GPS tracking system and active GPS tracking system. Passive Personal Tracking Devices system can monitor the location and store the data based on certain types of events, for example, you can download these data from an internal memory or on a memory card on this kind of GPS tracking system at your computer whatever how long you have been. But the active GPS tracking system is also known as a real-time system, it is good for tracking children, the eldly or the vehicles.

In our daily life, the most prominent application for the GPS Device Manufacturers In China system is navigation. In fact, there are many uses for a GPS device not just only for getting lost on a trip. well,How does GPS Tracking System Work? The control of the positioning system consists of different tracking stations that are located all over the world. These monitoring stations help tracking signals from the GPS satellites orbiting the earth continuously. At the same time, space vehicles transmit microwave carrier signals. The users of Global Positioning Systems have GPS receivers that convert these satellite signals so that one can estimate the actual position, speed and time. In fact, the operation of the system is based on a simple mathematical principle called trilateration. In addition, the GPS receiver need to have two conditions in order to know where you are, one is that the location is traced by at least three satellites and another is that the distance between the place and each of those space vehicles.

Applications of GPS Tracking System:Firstly, China GPS Device system can be used for trucking companies, they can install the GPS tracking devices to their trucks and know where their trucks accurately anytime and they can kepp their trucks on time and even improve delivery times being able to pinpoint those deliery times within even better accuracy. Otherwise, GPS technology can choose the best route to get the least gas mileage. Secondly, Car rental companies also can use these devices to know their cars’ route, they move from car to car to prevent during test drives. In fact, it is a great way to prevent car theft when vehicles have their GPS tracking device installed. Law also like to use it, when one of stolen cars has GPS tracking device, it is easier to track, and all of these tracking functions can be achieved with the GPS tracking devices. And insurance companies provide discounts on customer policies when that customer has a GPS device in their vehicle. Finally, As for private investigators, GPS tracking devices is too useful. Whatever purpose they have in mind when they track a person, they are glad to have this tool in their life. In our common life, people can use this function to know where their kids, the eldly and even your lovely pets are by mobile sevice such as mobile phones, watches. Except those, GPS tracking can be a useful feature for business owners, parents, friends and co-workers looking to connect with one another. GPS Tracking Apps provides a suit of Apps for the iPhone, iPad, Android operating system all of which can be used to track one another on a location-based social networking portal or from phone to phone. Want to know more related product info, you can enter into our GPS tracking device channel. http://www.iconcox.com/

Why We Need to Use Electronic Tracker ?

Global Position System, which stared from in the US in the late 1970s, it is widely recognized as the world’s most accurate method of navigation. The GPS is not generally visible in personal mobile devices, automobiles, surveying equipment, weather tracking systems, military munitions, electronic receivers, and other products incorporating the technology. Most individuals, for example, are not aware that data received from domestic and international financial institutions are dependent on the accurate synchronization of data streams provided by the GPS. Since its creation by the U.S. Department of Defense and its emergence into broader public awareness subsequent to becoming available for civilian use in 1984, the GPS has evolved into a wide range of technologies that have provided an enormous range of benefits for consumers.

In the 1990s, people began hearing about GPS (Global Position System) and in the 21 century we saw the technology rapidly expand into the mainstream and become part of commonly used item such as Electronic Tracker for car , in cell phones, even on shipments of merchandise to track their exact location as they are en route. For example, numerous police, fire, and emergency medical services have incorporated the GPS into vehicles to ensure the quickest possible response in life-or-death situations. Automobile manufacturers offer GPS-aided map displays that give directions to drivers on display screens and through synthesized voice instruction. The GPS has proven to be invaluable to hikers, golfers, cyclists, and other recreational users by providing precise directions. The system is likely to be incorporated into cellular phones to pinpoint location in emergency situations. Aviation, mining,construction, and other commercial and industrial activities have been enhanced by the precise positioning provided by the GPS. Although privacy concerns could present a significant barrier regarding the monitoring of individual activities, the GPS can be used to determine shopping patterns and customer profiles to improve sales and inventory management.

In our daily life, cell phone has become a necessary good and almost everyone all have one at hand. At the same time, some cell phones have the compatible software, and a vehicle that has a built in Electronic Tracking Device, it may also haves cell phone GPS tracking. By installing this GPS tracking device on a SUV or any type of vehicle and can get the software to work on the cell phone, a person can secretly track the whereabouts of that certain SUV. In fact, like this GPS tracking device is concealed operation, but it is useful for who wants to trace their vehicle. And it can reduce the criminal hijack cars such as crime, the crimes will easily be solved such as car napping, Kidnapping in the car. So for the car owners, GPS tracking device is necessary. Vehicle tracking system shown at the figure.

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There are better chance to regard to cell phone Smart Car Tracker. In general, it is easy to distinguish criminals’ vehicles. There are data base that law enforcement use to make them out. We all know it is much more difficult to seize the crimes than in concert, but by attaching a small magnetic box to the criminal’s vehicle that would allow the GPS signal to be sent to the mobile phone, the police are able to track the vehicle by means of anonymous mobile phone GPS tracking. With the development of technology through the GPS system and the satellite network, it become effortless to pin down a criminal. If it is implied around the world, the rate of crime will be reduced. All the hideouts of suspected drug lords or people under investigation can be tracked easily. I think it is a good invention for the peace of world.

In addition, for parents, maybe a good thing. it is typical for parents to want to track the where their children are. This may not be in good taste. But in some certain cases, GPS Kid’s Phone also can help to solve some family trouble. Except this, for the eldly, a cell phone GPS tracking device can help us to find their location easily, especially people with alzheimer’s disease. This is where cell phone GPS tracking becomes most valuable and applicable as a conspirator. Merely placing a GPS receive some where secretly in the automobile and install the applicable software on your cellphone. This will continuously send you important updates upon the location of the automobile via cell phone GPS tracking. We need not do some very complex operations, quite convenient for us.

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About GPS Kids Phone

When it comes to knowing your kid’s location, accuracy makes all the difference. And with a live map, compass, and distance countdown tracking, that’s exactly what the kids Chinese GPS Devices. Along with safety zone set up, a panic button, and two-way calling capabilities, this device covers all the must-haves that a kid needs to feel safe. It also comes with a long battery life—up to seven days—so you won’t have to worry about the device dying while your kid is away.

GPS trackers are easy to set up. After creating a personal account on the device manufacturer’s website, you simply turn on the tracker and sync. You can now view your tracker’s live whereabouts on the web or through a mobile app with great accuracy. Person Tracking Device are generally not hard to install, but installation varies depending on which one you purchase. Some attach to your car frame with magnets, others slip inside your glove box, and advanced trackers plug into a car’s diagnostic system. To help the people you love drive safely, invest in a GPS vehicle tracker. The five above are the best of the best and will help you sleep soundly knowing your vehicle is where it should be and your children are safe.

As your kid grows, so does their world. And although you want to let them explore, you also want to keep them safe.GPS Kids Phone, with GPS and RFID function (option) for the student,enables parents know their kids’ locations. It is a combination of low cost cell phones and wireless Motorcycle GPS Tracker to students. At the same time, it supports SOS and family numbers, prevent strangers from calling in, making it an ideal personal guard for elementary student. We are so excited to share the next generation GPS Kids Phone with you. Evolved from GK309, GK309E has tons of newly-added features tailored to kids. For one, WIFI positioning provides you with the ability to locate your children at any time. The unique “Listen in” mode allows you to hear what’s happening around them. Additionally, the device is waterproof, dust proof and has a battery that can hold a charge for up to a week. It is stylish, durable and useful.

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How to Guarantee the Safety of Your Kids

In many places in the world, all kinds of banned pursuits and unlawful events pose a threat to people’s life security, especially for the children who have no ability to protect theirselves. You have to be smart and choose most advanced technology to stay secure and healthy. In our daily life, as parents, it is so hard to keep kids indoors all the time, and it is unfair to them too. When your kids have to step out, such as schooling, or to socialize, attend birthday party or sports event and other kinds of things may make it quite difficult for parents to make sure their kids are safe. But with the GPS Device China , you need not worry any more.

Another great feature of this device is that you can track the position of your child not only from your computer but through a smartphone application as well. These apps are free to download. Not to mention, you can receive alerts on emails, text messages or both for your convenience. Setting up zones is another amazing feature that lets you specify areas where you don’t want your child to enter ever. As soon as your child enters that area you will be notified immediately so you can take a timely action. Why parents need a GPS Device Manufacturers In China for your children? With crime rates in cities on the rise, parents usually imagine all sorts of bad things that may happen to their children when they are out. Such as mugging and kidnapping on the streets, bullying and harassment at school, and falling into the wrong parties and other scenarios when parents let their children leave the house. These are all very serious issues, which is why any concerned and responsible parent needs GPS child tracking device. Once you get this spy software on your child’s smartphone, your worries end right then and there. Any responsible parent would like to keep a sharp eye on their children, especially when they are away at parties or with friends late at night. So get a GPS tracking device for you children, whatever a GPS phone, or a portable GPS tracker. Take action for it now.

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Concox is a reliable website to provide China GPS Device, here are many types to choose, such as a kid phone which designed specially for children and students, you can receive messages or emails from you mobile device when you put the GPS tracking device in your children, and you can get the accurate information easily. The most special thing is the SOS button on this phone, when your children meet an emergency, press this button to get the rescue in time. If you are interested in this device, welcome to contact us.For information at http://www.iconcox.com/

The application of GPS global use

The general overall uses of GPS vehicle tracking  are numerous and a single textbook cannot address all the GPS applications, especially when users create new ones almost every day. In this passage, we are going to talk about the application of GPS global use. A further additional arbitrary classification of navigation and survey uses is made to help organize the discussion of GPS applications.

Stand-alone users of GPS achieve the limited accuracy provided by the SPS. As mentioned earlier, the positional accuracy is about 10-20 m at the 95% probability level. The official values for position, height, and time have not yet been redefined after SA has been switched off.

An accuracy at the 10 m level suffices for many applications, particularly in navigation. For higher-accuracy requirements, DGPS is adequate for local, regional and even global applications. These applications mainly cover high-precision navigation on land, at sea, and in the air. Today’s navigation of civil aircraft is based on a variety of systems such as radio altimeters and inertial systems which form the flight management system. DGPS supports these systems and can also be used to supplement the Instrument Landing System (ILS) which is presently the international standard for approach and landing.

Vehicle Tracker Device


This was the planned primary use of GPS tracker device. Both military and civilian uses of the system in this mode are similar in that users wish to know their spatial locations as precisely as possible. For example, all types of aircraft and vessels may use GPS for en route navigation. But as aircraft are ready for landing or as vessels enter restricted waters, accuracy becomes more critical. Another factor critical to aircraft navigation is the high level.



Global application of GPS provides a powerful geodetic tool. This science is involved in monitoring global changes over time which is the key for understanding long-term geodynamical phenomena. Applications include measuring crustal deformations, postglacial rebound, volcanic uplift, plate tectonics, and earth rotation. In the past, Very Long Baseline Interferometry (VLBI) and Satellite Laser Ranging (SLR) techniques have been used for this purpose. GPS is not presently capable of replacing these techniques but it will be used to augment them and provide more cost-effective solutions to geodetic problems.


Timing and communications

Another global use of GPS vehicle tracker device is in global determination of accurate time. High accuracy timing has many scientific applications such as coordinating seismic monitoring and other global geophysical measurements. Inexpensive GPS receivers operating on known stations provide a timing accuracy of about 40 nanoseconds (95 % probability level) with only one satellite in view. With more sophisticated techniques, one can globally synchronize clocks even more precisely and an achievable accuracy of 1 nanosecond is considered possible.

Global communication depends upon precise coordination to pack as many data bits into a given period of time as possible. GPS should make it possible to increase the overall efficiency of communication, allowing many more users per unit of time than is presently possible.

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GPS tracking device not only can be used in the vehicle

GPS or Global Positioning System, allows anyone to track your position at anytime and anywhere. It replies on the wireless signals which sent by satellites in geostationary orbit to GPS receivers. Concox produced some GPS tracking products which based on this GPS tracking technology, including personal GPS tracking system, vehicle GPS tracking system and asset GPS tracking system. Concox uses GPS in our innovations which designed for business customers. Our GPS vehicle tracking system links your fleet with the office and uses vehicle tracking data to provide valuable business insights and we can know the reports on the internet by our mobile device. Our solutions make vehicle GPS Device Manufacturers In China easy to track the location of your vehicles, improve fuel efficiency and manage workflow and job dispatch with Bluetooth.

GPS Device China not only can be used in the vehicle, but also can be used for the mobile device, the tracking systems also can be installed into the mobile phone, in Concox, there are two types for kids and seniors. we can know their location easily and the SOS button is designed specially for them when they are in trouble.While making the final decision, you also need to check if the device is waterproof. With regards to battery life, some devices offer a long battery life that lasts between seven to ten days, while others last for about four days, on a single charge. If you are still not sure about which device to buy, ask yourself some questions like: Will I use this device everyday? Is it compatible with my phone? What do I know about the software interface? Does the device match my fashion sense?


Concox GPS portable trackers are tiny and cost-effective. We will find that the cost is more than worth it for the reassurance these can provide. For the kids, you can know about their heading ways and whereabouts whenever you want to find them. This gives you a lot of security. Most portable GPS trackers these days come with an emergency button that makes it easy for them to notify you. This reduces lots of hurts and accidents. For the lovers, you can also track them when you want to know where they are and what they do. You want to make sure whether they are honest or cheating. This is useful for you to do so. For the elder, you may want them not to go out of the certain zone you have designated for them. Portable GPS trackers allow you to always keep track of what area a person is in so you can know if they leave that designated area.

Concox now provides top-quality China GPS Device at the best prices coupled with our high level of support and customer service. Concox aims to deliver top-quality wireless equipment at the best prices. Offering topnotch customer service and custom kits and installations for corporate clients, Concox ensures customer satisfaction across its client base. For more information, please visit www.iconcox.com.

Getting familiar with common GPS receiver features

A number of GPS receivers are on the market. Usually a GPS receiver with more features costs more.

GPS manufacturers have done a pretty good job making user interfaces easy to use. After you know the basic concepts of GPS receivers and are familiar with a manufacturer’s user interface, a GPS tracker device  is usually as easy to use as a cellphone and easier to use than a personal computer.

Display and output

GPS receivers have three choices for information display or data output:

         (1) Monochrome LCD screen: Most GPS receivers have a monochrome liquid crystal display (LCD) screen.

(2)Color screen:  These are especially useful for displaying maps.

Color screens usually have shorter battery lives than monochrome ones.         (3) No screen: Some GPS receivers only transmit data through an expansion slot or a cable; a receiver with a cable is often called a mouse GPS receiver because it resembles a computer mouse. Such receivers are designed to interface with a laptop computer or PDA running special software. All GPS data is sent to the laptop and processed there with mapping soft-ware. A Magellan SporTrak GPS receiver is shown on top of the laptop for comparison. Most GPS receivers that have screens can output data to a PC or PDA.


A GPS receiver alarm can transmit a tone or display a message when you approach a location that you specify. This feature can be especially useful when you’re trying to find a place and visibility is limited by darkness or inclement weather — or you’re busy doing something else and aren’t looking at the GPS receiver screen.

Built-in maps
Every GPS receiver has an information page that shows waypoints and tracks. The page is a simple map that plots travel and locations. It doesn’t show roads, geographic features, or man-made structures.

Some GPS receivers have maps that show roads, rivers, cities, and other fea-tures on their screens. You can zoom in and out to show different levels of detail. The two types of map receivers are

Basemap: These  vehicle GPS  tracking devices have a basemap loaded into read-only memory that contains roads, highways, water bodies, cities, airports,

railroads, and interstate exits.

Uploadable map: More detailed maps can be added to this type of unit (in either internal memory or an external memory card). You can install road maps, topographic maps, and nautical charts. Many of these maps also have built-in databases, so your GPS receiver can display restau-rants, gas stations, or attractions near a certain location.

Electronic compassAll GPS receivers can tell you which direction you’re heading — that is, as long as you’re moving. The minute you stop, the receiver stops acting as a compass. To address this limitation, some GPS receivers incorporate an elec-tronic compass that doesn’t rely on the GPS satellites.


Like with an old-fashioned compass, you can stand still and see which direc-tion your GPS receiver is pointing toward. The only difference is that you see a digital display onscreen instead of a floating needle.


Electronic compasses need to be calibrated whenever you change batteries. If your GPS unit has an electronic compass, follow your user guide’s instruc-tions to calibrate it. Usually, this requires being outside, holding the GPS unit flat and level, and slowly turning in a circle twice.

Vehicle Tracker Device


The elevation or altitude calculated by a GPS receiver from satellite data isn’t very accurate. Because of this, some GPS units have altimeters, which provide the elevation, ascent/descent rates, change in elevation over distance or time, and the change of barometric pressure over time. On GPS units with an electronic altimeter/barometer, calibrating the altimeter to ensure accuracy is important. To do so, visit a physical location with a known elevation and enter the elevation according to the directions in your user’s guide. Airports are good places to calibrate your altimeter or get an initial base reading; their elevation is posted for pilots to calibrate their air-planes’ altimeters. If you’re relying on the altimeter/barometer for recre-ational use, I recommend calibrating it before you head out on a trip.

Increasing accuracy

Some GPS receivers have features that allow you to increase the accuracy of your location by using radio signals not associated with the GPS satellites. If you see that a GPS receiver supports WAAS or Differential GPS, it has the potential to provide you with more accurate location data.


Wide Area Augmentation System (WAAS) combines satellites and ground sta-tions for position accuracy of better than three meters. Vertical accuracy is also improved to three to seven meters.

Coast Guard DGPSDGPS signals are freely broadcast by a series of U.S. Coast Guard stations in the United States. Whether you can receive these Coast Guard broadcasts depends on your location.

Commercial DGPS

DGPS services are offered commercially for the surveying market. You can rent or purchase electronic and radio equipment for gathering precise loca-tion information in a relatively small area.


Well, yes, a GPS unit has to have an antenna to receive radio signals to do you any good. Several types are available, each with its advantages.

Internal antennas

All GPS receivers have one of two kinds of built-in antennas. One antenna design isn’t superior to the other; performance is related to the receiver’s antenna size. (Cough . . . bigger is better.)


An internal patch antenna is a square conductor mounted over a groundplane. Patch antenna models reacquire satellites faster after losing the signal.

For best performance with an internal patch antenna, hold the receiver face up and parallel with the ground.

Quad helix

An internal quadrifilar helix antenna is a circular tube wrapped with wire. Quad helix antennas are more sensitive and work better under tree cover than the other types.

For best performance with an internal quad helix antenna, hold the receiver so that the top is pointing up to the sky.

External antennas

Some GPS receivers have connectors for attaching external antennas. An external antenna is useful if the GPS receiver’s view of the sky is otherwise blocked, like in a boat, a car, an airplane, or a backpack.

Reradiating antennas

If a GPS receiver doesn’t have a jack for connecting an external antenna, you can improve the reception with a reradiating antenna. These antennas work just as well as conventional external antennas that plug into a GPS receiver.

A reradiating antenna combines two GPS antennas:

         (1)One antenna receives the GPS signal from the satellites.

         (2)The other antenna is connected to the first and positioned next to the GPS vehicle tracker device internal antenna.

Internal memoryA receiver’s internal memory holds such data as waypoints, track logs, routes, and uploadable digital maps (if the model supports them). The more memory the receiver has, the more data you can store in it. All the data that’s been stored in the GPS receiver is retained when the device is turned off.

External storage

Some GPS receivers aren’t limited to internal memory for storage, using support memory cards that can be plugged into the receiver to store data. External memory can be either

         (1)Manufacturer proprietary data cards

         (2)Generic (and less expensive) storage, such as

•   MultiMediaCard

•   Secure Digital

Accessory programs

Many GPS receivers have built-in accessory programs that display various handy features such as

         (1)Calendars with the best time to hunt and fish

         (2)Sunrise, moonrise, sunset, and moonset tables

         (3)Tide tables



User interface modes

Some GPS receivers have simple and advanced user interface modes.

         (1)Simple mode: This displays only often used commands and features.This is an excellent option for the novice user who wants to use basic GPS receiver functions without being distracted or confused by the many other features.         (2)Advanced mode: This shows all commands and features.
Synthesized voice

Some models of GPS receiver, designed primarily for automotive use, have a synthesized voice that provides you with route-finding information. Although this feature has been available as an option in some luxury cars for many years.

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