Rearview mirror camera is successful in reducing crimes

Many security consultants and security firms are hired to advise taxi companies on methods to help themselves. Situational crime prevention measures, such as partitions between drivers and passengers, video cameras, and GPS rearview mirror , are possible solutions that can reduce the risk to drivers. The most recent statistics from the U.S. Bureau of Labor Statistics reported that cab drivers are ten times more likely to be killed on the job than the average worker. The use of electronic video surveillance (surveillance and security cameras and closed-circuit television (CCTV) systems) has increased rapidly in both the private security industry and law enforcement. Electronic video surveillance systems can passively record and play back video at certain intervals, be actively monitored by security personnel, or be used in a combination of these methods. Some evidence suggests that video surveillance is successful in reducing and preventing crimes and is helpful in prosecuting criminals.
Recall that, in the London Underground bombings in 2005, video from the vast network of public surveillance cameras helped police identify the suicide bombers within days. Electronic video surveillance has several objectives, including a reduction in crime and disorder, making people feel safer, and providing evidence for police investigations. Prior to using such surveillance, a basic security audit is generally conducted to determine whether the electronic video surveillance is needed and how it should be designed. The two basic recording processes in electronic video surveillance are videocassette recorders and digital recorders. A switcher allows switching between multiple cameras and multiplexes, allowing recording and displaying images of several cameras simultaneously. Surveillance cameras can operate in low-light and nighttime situations by using infrared (light that cannot be seen by the human eye) technology located at the camera head to provide “invisible” lighting for the camera’s use. VCR recorders had been standard in electronic video surveillance; however, this technology has had drawbacks, and tapes become damaged each time they are run through the VCR, resulting in an absence of detail. Digital video systems provide advantages to standard VCR recording in image quality and ease of use. The latest in CCTV technology is the digital video recorder (Rearview Mirror DVR ).

robber and the thief hijacks the car

A DVR records images directly to a conventional computer hard drive as bits of data, instead of recording analog images to a moving medium like VHS tape. This is fundamentally similar to the technology used in consumer products like TiVo and Ultimate TV. Digital recording is a relatively new technology and in a state of constant flux and evolution. DVRs are sensitive electronic components that are vulnerable to power strikes and electrical interruptions and that need to be carefully handled. Digitally stored images can be preserved indefinitely and can be replicated without loss of quality. Smart DVR also allow for simultaneous recording and playback, better picture quality than tape, and quick searches of stored data using a wide variety of parameters. Digital closed-circuit television is one of the fastest-growing segments of the security industry. There is debate in the electronics industry about the value and best use of DVRs; however, most experts believe that they make credible and effective event-based recording a reality. The management of CCTV footage is simplified and the effectiveness is enhanced. Many DVRs have network compatibility and can be programmed to connect to a remote site, over either a network or a dial-up connection. A copy of the video clip can then be transmitted, allowing security to quickly assess the site status. Digital recording also results in reductions in maintenance costs and wasted personnel hours spent searching for video clips.
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Better Living Through GPS Tracking Devices

It was just a few years since the launch of the first GPS satellite. As the constellation grew—and, along with it, a method of tracking that further enhanced the ability of humans to observe and gather data—the question of sensory augmentation and the law would grow more urgent.

For an airport of its size, Newark Liberty is squeezed into a fairly small footprint. The team that set up the GBAS receivers found that the only spot at the airport that provided full coverage was next to a runway at the airport’s eastern edge. Each receiver sat within 200 meters of the New Jersey Turnpike.

The freeway’s centrality guarantees that a sizable amount of its traffic is always commercial vehicles. A significant number of these, it turned out, are driven by people who possess “personal privacy devices,” a euphemistic term for GPS jammers. The drivers carried these jammers to foil the tracking apparatuses set up by their bosses to monitor the whereabouts of employees. Although operating one is illegal, they are cheap—often under $100—and easy to obtain from Internet vendors. Small and innocuous, many plug right into a vehicle’s dashboard cigarette lighter. They form a little interference bubble in the area surrounding the jammer, stopping the GPS signal from getting through. This interference was disrupting the GBAS receivers.

The discovery came as a shock to the GBAS team. “We were generally aware of people with jammers in the cars,” says Sam Pullen, leader of the Stanford GPS Lab’s GBAS research group. “But we knew those devices were low-power. So we suspected there would be fewer bumps and that we’d rarely see them. We didn’t think about it that closely, but there was no reason to think that car-based jammers by themselves would be much more frequent than what we had seen previously.”

GPS tracking device

Authorities began a stakeout of the Turnpike. But pinpointing the source of the jammers was difficult, so the GBAS outages continued. On April 29, the effort finally paid off. Police were positioned on the Turnpike, near the runway, when the interference began. It seemed to coincide with the passing of a certain truck. They raced after it and motioned the driver to pull over. The jammer was right there on the dashboard. The driver made no attempt to hide it. In exchange for handing it over, the police let the driver go on his way with a warning.

Moving the GBAS array was not an option. No other spot could so effectively cover the airport. Instead, the team made some adjustments to the software, which mitigated the problem a bit, but not completely. Cars and trucks with GPS jammers continued to use the Turnpike, and sometimes they jammed the GBAS. Throughout the summer months, the team monitored the problem—the monotonous jamming blips from trucks passing through America’s most dangerous two miles.

Until one day in August, when the static suddenly got worse. By the second half of the 1980s, companies like Trimble and Qualcomm were exploring the market for GPS  tracking devices that would allow trucking companies to monitor their drivers’ whereabouts. A GPS tracker is simply a GPS receiver integrated into some kind of communication device that periodically transmits or records that location. The problem for early fleet management systems was not so much the GPS aspect, as it was finding radio frequencies usable over wide geographic areas to transmit the coordinates back to the monitoring centers. But the customers were there. Three years after it debuted, Qualcomm’s Omnitracs system had signed up about 100 trucking companies and was monitoring the whereabouts of 15,000 trucks. Drivers were required to enter messages onto a dashboard-mounted terminal. Satellite dishes on the trucks relayed the information to Qualcomm’s San Diego headquarters, which forwarded it to the driver’s dispatchers.

As cellular networks developed and the cost of access decreased, GPS tracking became a more realistic proposition. Between 1992 and 1997, U.S. Census Bureau “vehicle inventory and use” surveys found that the percentage of commercial trucks on the road being tracked electronically rose from roughly one in ten to nearly one in four. The process of tracking via GPS became much simpler. “A GPS tracking device is like a mini-cell phone, more or less,” says Ryan Driscoll, the marketing manager at GPS Insight, an Arizona-based company that designs GPS tracking software. At regular intervals, the device transmits the GPS reading to a monitor, either a live human or a computer that gathers and archives the location data.

By 2005, companies and government organizations were using GPS to track 1.3 million fleet vehicles. Analysts projected that the North American fleet management market alone would grow to $7 billion over the next few years. More than half of all fleets with 100 or more vehicles now use a GPS fleet management system—for companies with more than 350 vehicles, the adoption rate is approaching 60 percent. The worldwide fleet management industry, valued at $12 billion in 2014, is on track to be worth more than $35 billion by 2019, with Asian and Pacific markets showing the highest growth rates. In Delhi, a public-private partnership between the Indian government and an infrastructure investment company has installed GPS trackers on all 60,000 public rickshaws, to prevent drivers from gouging tourists by taking longer routes. In China, GPS tracking is used to control the black market in “gutter oil,” recycled cooking oil that is combined with industrial waste and other effluents, which may account for 10 percent of all cooking oil used in the country. GPS trackers on garbage trucks keep track of where oil is collected, so that officials can ensure that the amount collected does not mysteriously decrease before disposal.

Fleet management is one of the fastest-growing segments of the overall GPS industry, and the largest segment of the telematics industry—companies that specialize in processing and transmitting real-time data from vehicles. It has proven itself to be recession-proof. “Our businesses thrive in a bad economy,” Driscoll says. “When expenses are tight, they need this. They can’t afford to waste fuel. They can’t afford to pay drivers for wasted labor hours. They’ve got to shave as many costs around the entire operation as possible.”

Among the private trucking fleets that use portable GPS tracking device, two-thirds integrate the system with other data gathering, to analyze job performance. The most extreme example may be United Parcel Service, whose drivers—“among the most regimented workers in the country outside those on an assembly line,” according to labor journalist Jane Slaughter—use trucks outfitted with 200 telematics sensors, recording such metrics as how hard a driver brakes and how long it takes to deliver a package and get a signature. In much the same way that Todd Humphreys described GPS in a drone as the “bulwark,” surrounded by and supporting other navigation tools, GPS location tracking in fleets is the foundation supporting many kinds of telematics data. Perhaps a clue as to why vehicle GPS tracking device is so seductive as a gateway to other information is that fleet managers overwhelmingly rate “vehicle location” as the principal benefit of GPS tracking, far ahead of fuel consumption and cost control. As the sales manager of a GPS fleet management company put it, summing up the prevailing attitude of his clients, “I want to know my employees are working, not at the Circle K having a soda.”

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How many GPS Receiver Features you may need to know?

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 Tracking 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:

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

Color screen: These are especially useful for displaying maps.

Color screens usually have shorter battery lives than monochrome ones.

   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. The picture below shows a DeLorme Earthmate GPS unit attached to a laptop. 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’s screen size depends on the receiver’s size. Smaller, lighter models have small screens; larger units sport bigger screens.Generally, a bigger screen is easier to read. Different models of GPS receiver also have different pixel resolutions; the higher the screen resolution, the more crisp the display will be. For night use, all screens can be backlit.

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 areBasemap: These GPS tracker device have a basemap loaded into read-only memory that contains roads, highways, water bodies, cities, airports,railroads, and interstate exits.

Basemap GPS receivers aren’t expandable, and you can’t load more detailed maps to the unit to supplement the existing basemap.

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.

Refer to the picture to see screens from a GPS receiver with a simple plot map and another GPS tracking device with an uploadable map.

GPS receivers that display maps use proprietary map data from the manufacturer. That means you can’t load another manufacturer’s or software company’s maps into a GPS receiver. However, clever hackers reverse-engineered Garmin’s map format. Programs on the Internet can create and upload your own maps to Garmin GPS receivers; GPS mapper is popular.A handheld GPS receiver’s screen is only several inches across. The limitations of such a small display certainly don’t make the devices replacements for traditional paper maps.

Electronic compass
All 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 electronic compass that doesn’t rely on the GPS satellites.


Like with an old-fashioned compass, you can stand still and see which direction your GPS receiver is pointing toward. The only difference is that you see a digital display onscreen instead of a floating needle.On some GPS receivers, you need to hold the unit flat and level for the compass to work correctly. Other models have a three-axis compass that allows the receiver to be tilted.

Paying attention to these factors can improve the performance and convenience of an electronic compass:

   Magnetic fields: Metal objects, cars, and other electronic devices reduce the accuracy of any electronic or magnetic compass.

   Battery life: Using an electronic compass can impact battery life. Some GPS receivers have settings that turn off the compass or only use it when the receiver can’t determine a direction from satellite data.

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

Altimeter: 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. Calibrated and used correctly, barometric altimeters can be accurate within 10 feet of the actual elevation. Knowing your altitude is useful if you have something to reference it to, such as a topographic map. Altimeters are useful for hiking or in the mountains.

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.


WAAS is a Federal Aviation Administration (FAA) system, so GPS can be used for airplane flight approaches. The system has a series of ground-reference stations throughout the United States. These monitor GPS satellite data and then send the data to two master stations — one on the west coast and the other on the east coast. These master stations create a GPS message that corrects for position inaccuracies caused by satellite orbital drift and atmospheric conditions. The corrected messages are sent to non-NAVSTAR satellites in stationary orbit over the equator. The satellites then broadcast the data to GPS receivers that are WAAS-enabled.GPS tracker device that supports WAAS has a built-in receiver to process the WAAS signals. You don’t need more hardware. Some GPS receivers support turning WAAS on and off. If WAAS is on, battery life is shorter (although not as significantly as it is when using the backlight). In fact, on these models, you can’t use WAAS if the receiver’s battery-saver mode is activated. Whether you turn WAAS on or off depends on your needs. Unless you need a higher level of accuracy, you can leave WAAS turned off if your GPS receiver supports tog-gling it on and off. WAAS is ideally suited for aviation as well as for open land and marine use. The system may not, however, provide any benefits in areas where trees or mountains obstruct the view of the horizon.
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Uploading Firmware Revisions to Your Motorcycle GPS Tracker

Just like software vendors, GPS tracking manufacturers find bugs and add enhancements to their products. New versions of a GPS receiver’s operating system can be upgraded through the receiver’s firmware (the updatable, read-only software that’s embedded in a hardware device). Check that your GPS receiver’s firmware is current every few months or so, especially if your receiver is a newly released model. GPS manufacturers offer free downloads of firmware upgrades on their Web sites, and these bug-fixes or new features can definitely make your GPS receiver perform better.
To upgrade your firmware
1. Check the current version of your GPS receiver firmware.
Sometimes this is displayed when the GPS receiver is turned on, or it might be shown on an information page. Consult your user’s guide or the manufacturer’s Web site for specific instructions on how to get this information for your model.
2. Visit the manufacturers’s website and go to the software updates section.

If you have a JIMI GPS receiver, you can sign up for automatic e-mail notification of firmware upgrades at the JIMI Web site. I expect other GPS Device Manufacturer to start offering this service.

Motorcycle GPS Tracker

3. Find your GPS receiver model and check its manufacturer’s website for the latest firmware version.

If your firmware is older than the current version on the website, follow the online instructions to download the firmware installer. Usually, the higher the version number, the more recent the firmware version. Make sure that the firmware installer you download is for your GPS receiver model. If you upload firmware designed for a different model, plan on the GPS receiver not working until you load the proper firmware.
4. Follow the installation instructions that come with the downloaded file Usually firmware installation files come in two forms:
A standalone program that runs on your computer, connects to the GPS receiver, and sends the upgraded firmware to the receiver. You need to have a PC interface cable attached to both the computer and the GPS receiver.
A special file that you copy to a memory card. When the GPS receiver starts, it searches the card to see whether a firmware upgrade is present. If it is, the receiver uploads the upgrade. After the upgrade is successful, you can erase the firmware upgrade file from the memory card.
Upgrading a GPS receiver’s firmware is pretty easy; not too much can go wrong. About the only thing that can get you in trouble is if the GPS receiver’s batteries die midway through a firmware upload. A firmware upgrade usually only takes a few minutes to complete, but make sure that your batteries aren’t running on empty before you start. Some firmware update software works only on COM ports 1 through 4. If you’re using a USB adapter, (which is usually set to COM port 5 or higher) and are having problems connecting to the GPS receiver, try reassigning the existing COM ports to numbers higher than the USB adapter’s port; then set the adapter’s port number to 1. Refer to online Windows help (choose Start➪Help) and perform a search for device manager to get more information on changing device settings.
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GPS tracking solutions – 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 GPS 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 GPS; 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.

GPS tracking devices
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 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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Vehicle GPS tracking devices – About V2V

Direct communication between vehicles allows information exchange without requiring any fixed infrastructure or base stations. The location and velocity of vehicles is constantly changing, and the RF communication range is of fairly short distance; therefore, the set of vehicles that can directly communicate will constantly change over a short period of time. This dictates that the physical layer and the network must be capable of operating in an ad hoc, decentralized manner, although coordination and synchronization through GPS ( GPS tracking device for cars ) time signals are possible. Any two nodes must be able to communicate securely whenever they are within communication range.
In a V2V network we can distinguish two modes of communication, usually designated as:
• Single hop: Two vehicles are close enough to communicate directly with each
other (either broadcast or point to point) with low latency.
• Multihop: Vehicles that can not directly communicate may forward messages through intermediate nodes.
Multihop communication has been the subject of much research, but no standard has emerged, and in fact the technical difficulties of establishing routing and acknowledgment protocols along with potentially high latency may limit its use to very specific applications such as medium range emergency notification or other sparse broadcast communication applications.GPS Tracker For Car

Many early experiments in V2V communication were carried out with standard wireless LAN technologies, and some success was achieved at ranges of up to several hundred meters. But the technical difficulties inherent in vehicle and traffic situations, including the high relative velocities (Doppler effects), a safety critical low latency requirement, operation in an urban environment (multipath), and spectrum competition from other users in unlicensed frequency bands renders this an unrealistic solution for commercial deployment. The IEEE 802.11p/WAVE standards have recently emerged as the current consensus for the implementation of V2V and local V2I communications.
Positioning of the vehicle is provided by a Differential GPS (DGPS)—Inertial Navigation System ( vehicle GPS tracking systems ). This vehicle position updates the vehicle positioning computer to make corrections to bring the vehicle back to its pre-programmed track. While the vehicle generally operates in an automated mode (autoheading and preprogrammed track), its operation can be immediately over-ridden by moving the rudder joystick or the throttle at the surface console.
There are existing standards for digital communication using subcarriers of standard AM and FM radio broadcast stations. Applications include channel and programming information, commercial paging systems, weather, news, and traffic information, stock market quotes, and GPS differential correction services. The data rate is quite low (on the order of 1 Kbps) and the services often require paid subscriptions. Many of these applications are declining in popularity due to the availability of other, faster technologies. Satellite radio offers a similar unidirectional capability at much higher data rates, for example, Sirius Traffic, a subscription service for real-time traffic data.
As we have previously mentioned, cellular telephone and broadband data services have become ubiquitous. Pricing, at least for individual users, is still rather high, but vehicle OEM and other providers have negotiated pricing arrangements for particular services. Perhaps the best known is the GM On Star service, which provides driver information including directions, stolen vehicle location, crash detection and emergency services notification, and other services. BMW Assist is a similar service. To date, these services have been implemented by specific vehicle manufacturers and are not available outside their vehicle brands.
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Errors That Can Affect Tracking Device Tracking Data

The following are some of the main errors that can potentially affect data acquired from GPS sensors (points 1 to 5), and that can be classified as GPS location bias, i.e. due to a malfunctioning of the GPS sensor that generates locations with low accuracy (points 6 to 9):
1. Missing records. This means that no information (not even the acquisition time) has been received from the sensor, although it was planned by the acquisition schedule.
2. Records with missing coordinates. In this case, there is a GPS tracking device failure probably due to bad GPS coverage or canopy closure. In this case, the information on acquisition time is still valid, even if no coordinates are provided. This corresponds to ‘fix rate’ error.
3. Multiple records with the same acquisition time. This has no physical meaning and is a clear error. The main problem here is to decide which record (if any) is correct.
4. Records that contain different values when acquired using different data transfer procedures (e.g. direct download from the sensor through a cable vs. data transmission through the GSM network).
5. Records erroneously attributed to an animal because of inexact deployment information. This case is frequent and is usually due to an imprecise definition of the deployment time range of the sensor on the animal. A typical result is locations in the scientist’s office followed by a trajectory along the road to the point of capture.
GPS tracking devices
6. Records located outside the study area. In this case, coordinates are incorrect (probably due to malfunctioning of the GPS sensor) and outliers appear very far from the other (valid) locations. This is a special case of impossible movements where the erroneous location is detected even with a simple visual exploration. This can be considered an extreme case of location bias, in terms of accuracy.
7. Records located in impossible places. This might include (depending on species) sea, lakes or otherwise inaccessible places. Again, the error can be attributed to GPS sensor bias.
8. Records that imply impossible movements (e.g. very long displacements, requiring movement at a speed impossible for the species). In this case, some assumptions on the movement model must be made (e.g. maximum speed).
9. Records that imply improbable movements. In this case, although the movement is physically possible according to the threshold defined, the likelihood of the movement is so low that it raises serious doubts about its reliability. Once the location is tagged as suspicious, analysts can decide whether it should be considered in specific analyses.
GPS sensors usually record other ancillary information that can vary according to vendors and models. Detection of errors in the acquisition of these attributes is not treated here. Examples are the number of satellites used to estimate the position, the dilution of precision (DOP), the temperatures as measured by the sensor associated with the tracking platform and the altitude estimated by the GPS. Temperature is measured close to the body of the animal, while altitude is not measured on the geoid but as the distance from the center of the earth: thus in both cases the measure is affected by large errors.
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GPS tracker Modernization and GNSS

The most important hardware in a GPS surveying operation are the receivers. Their characteristics and capabilities influence the techniques available to the user throughout the work, from the initial planning to processing. There are literally hundreds of different GPS receivers on the market. Only a portion of that number is appropriate for GPS surveying and they share some fundamental elements. They are generally capable of accuracies from submeter to subcentimeter. They are capable of differential GPS (DPGS), real-time GPS, static GPS, and other hybrid techniques. They usually are accompanied by postprocessing software and network adjustment software. And many are equipped with capacity for extra batteries, external data collectors, external antennas, and tripod mounting hardware. These features, and others, distinguish GPS receivers used in the various aspects of surveying from handheld GPS units designed primarily for recreational use.

portable GPS Tracker, like any electronic tracking devices, must collect and then convert signals from GPS satellites into measurements. It is not easy. The GPS signal has low power to start with. An orbiting GPS satellite broadcasts this weak signal across a cone of approximately 28º of arc. From the satellite’s point of view, about 11,000 miles up, that cone covers the whole planet. It is instructive to contrast this arrangement with a typical communication satellite that not only has much more power, but a very directional signal as well. Its signals are usually collected by a large dish antenna, but the typical GPS receiver has a very small, relatively nondirectional antenna. Fortunately, antennas used for GPS receivers do not even have to be pointed directly at the signal source.

Stated another way, a GPS satellite spreads a low power signal over a large area rather than directing a high power signal at a very specific area. In fact, the GPS signal would be completely obscured by the huge variety of electromagnetic noise that surrounds us if it were not a spread spectrum coded signal. The GPS signal intentionally occupies a broader frequency bandwidth than it must to carry its information. This characteristic is used to prevent jamming, mitigate multipath, and allow unambiguous satellite tracking.
The configuration of the GPS Space Segment is well-known. A minimum of 24 GPS satellites ensure 24-hour worldwide coverage. But today there are more than that minimum on orbit. There are a few spares on hand in space. The redundancy is prudent. GPS, put in place with amazing speed considering the technological hurdles, is now critical to all sorts of positioning, navigation, and timing around the world. It is that very criticality that requires the GPS modernization. The oldest satellites in the current constellation were launched in 1989. Imagine using a personal computer of that vintage today. It is not surprising that there are plans in place to alter the system substantially. What might be unexpected is many of those plans will be implemented entirely outside of the GPS system itself.
In fact, the goal of a single electronic tracking devices that can track all the old and new satellite signals with a significant performance improvement looks possible. But after all, the main attraction of interoperability between these systems is the greatly increased number of satellites and signals, better satellite availability, better dilution of precision, immediate ambiguity resolution on long baselines with three-frequency data, better accuracy in urban settings, and fewer multipath worries. Those are some of the things we look forward to. It is beginning to look like at least some of those things are achievable.
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The development tools available for tracking device

The development tools available for GPS application design vary depending on the complexity of the target system and the GPS solution being used. Most GPS Solution vendors offer software tool suites that allow a developer to communicate with the GPS receiver through the serial port of a personal computer. These software tools typically use messages compatible with the standard NMEA (National Marine Electronic Association) format, but many vendors also offer their own customized sets of messages and message formats.

The more advanced development tools, available for some GPS chip sets, are intended to help the application developer integrate their software with the GPS tracking software running on the same MCU. Because of the hard real-time constraints typical of GPS software implementations, the most efficient way to enable the smooth integration of the GPS tracking device with the application software is through a clearly defined software API. With a standard interface to the GPS software and the necessary development/debugger tools to support it, an application developer can easily configure the GPS receiver software, enabling access to the appropriate PVT information by the application as needed. For an illustration of the basic software architecture of a GPS enabled application running on a single MCU that is supported by this type of tool suite.

For those developers that have the skill of designing the entire GPS receiver circuit into their application, several semiconductor manufacturers now offer GPS chip set solutions. These chip sets, offered with either complete or partial reference designs and control software, enable the designer to integrate GPS into an application at the lowest possible cost, while also conserving power, board space and system resources. However, this high level of integration is achieved at the expense of doing the RF and IF circuit layout and software integration in-house, which can take significant resources and effort. The custom chip sets used for the original GPS receivers often had up to seven ICs, including the external memory chips, amplifiers, downconverter, correlator ASIC and system processor, in addition to a variety of discrete components. Continuous advances in the performance and integration level of MCUs have greatly increased the performance of the newer GPS chip sets while reducing the power consumption and physical size of the complete system. System-on-a-Chip (SoC) technology has resulted in the integration of the GPS correlator directly onto the MCU, along with embedded RAM, ROM and FLASH memory. In some cases, this increased level of integration has reduced the device count down to a mere two ICs and a handful of discrete components, further decreasing the cost and development effort required.Even more recently, high-performance RISC MCUs have begun showing up in low-cost GPS chip set solutions. These powerful processors have many more MIPS available for GPS computations, which in turn increases the overall performance and reliability of the GPS tracking solution  . This level of computational power is making it possible to execute dead reckoning or WAAS algorithms on the same processor as the GPS algorithms, further improving the accuracy of the positioning solution at little or no increase in chip set cost. This diagram illustrates all of the functional blocks required by a basic GPS system, including an active antenna, a downconverter with an integrated temperature sensor, and a correlator integrated onto a basic microcontroller, along with the additional MCU peripherals required to perform a basic tracking loop routine and calculate a PVT solution.

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Applications of spaceborne GPS to Earth science

With the recent completion of the Global Positioning System constellation and the appearance of increasingly affordable spaceborne receivers, GPS is moving rapidly into the world of space flight projects. Indeed, owing to the great utility and convenience of autonomous onboard positioning, timing, and attitude determination, basic navigation receivers are coming to be seen as almost indispensable to future low earth missions. This development has been expected and awaited since the earliest days of GPS. Perhaps more surprising has been the emergence of direct spaceborne GPS science and the blossoming of new science applications for high performance geodetic space receivers.
Applications of spaceborne GPS to Earth science include centimeter-level precise orbit determination (POD) to support ocean altimetry; Earth gravity model improvement and other enhancements to GPS global geodesy; high resolution 2D and 3D ionospheric imaging; and atmospheric limb sounding (radio occultation) to recover precise profiles of atmospheric density, pressure, temperature, and water vapor distribution. Figure 1 offers a simplified summary of the Earth science now emerging from spaceborne GPS.
GPS tracking devices
Conventional single- and dual-frequency GPS tracking device have been flown in space for basic navigation and (increasingly) attitude determination on a number of recent missions. Consistent with these different uses, there has developed in recent years a two-tiered user community for GPS in space: those seeking basic, moderate-performance GPS navigation, timing, and (in some cases) attitude determination, and those pursuing the more demanding science activities requiring the highest performance dual-frequency receivers. As the mission-dependent requirements within each group are diverse, a variety of receiver models for space use has emerged.· While that healthy situation is likely to continue, from the standpoint of the scientists it may be hoped that in the future the high end instruments will reach levels of size, cost, and generality of function that will allow them to serve both user classes economically, thus converting the most utilitarian satellites into potentially powerful science instruments. As GLONASS becomes established as a reliable navigation system we can expect to see considerably more commercial resources devoted to developing the technology for both the ground and space. A high performance spaceborne GPS/GLONASS receiver for navigation and science applications is currently under development by the European Space Agency and may fly within two years.
The utilitarian spaceborne GPS applications represent, in essence, a fulfillment of the GPS vision. They exploit GPS( tracking device), sometimes in clever ways, for purposes for which it was expressly intended. For the growing class of high-precision spaceborne science users surveyed here, the same cannot be said. GPS was not conceived with such uses in mind (indeed, their feasibility was generally recognized only after GPS deployment was well underway), and has not been altered in any way to accommodate them. Within these diverse scientific enterprises we find many examples in which GPS innovators have, through ingenuity and industry, coaxed a reluctant system to perform unexpected feats, thereby expanding the GPS mission. In the face of the seriously confounding security features known as selective availability and anti-spoofing, they have extracted from GPS levels of performance undreamed of by its architects.
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