JIMI Electronic

GPS Tracking Devices was designed to work outdoors. The signal from the GPS satellites is extremely weak, and the satellites are far away. The total radiated power from each satellite is just 27W, about the same power from a dim lightbulb. The satellites are more than 20,000-km high (about 55 times higher than the space shuttle flies). When the signal reaches the GPS receiver on the Earth, the received signal power is about 100 attowatts; “atto” means 10–18, and it is not a commonly used prefix. We typically express such low powers in terms of decibels. But it is useful to mention the attowatt just this once, to get a feel for how weak the received GPS signal really is. The received signal power is 100 attowatts when the receiver is outdoors; when the receiver moves indoors, the signals rapidly get weaker, by 10–100 times in a house,and by 100–1,000 times or more in a large building. However, it is not just indoors where GPS has signal problems; the weak signal is a problem outdoors...

The Global Positioning System (GPS) is becoming, and promises to remain for some time, one of the most important geodetic measurement systems. The contributions to date of GPS geodesy are truly revolutionary, encompassing such diverse applications as measurements of crustal deformation, precise positioning of mobile platforms and monitoring of ionospheric conditions. When one considers the accuracy obtainable with GPS and the relatively low cost for acquiring this technology, the full impact of GPS over the next decade is indeed very difficult to estimate. It is our impression that four years later it is still difficult to estimate the full impact of the GPS in all mentioned areas. Meanwhile the  portable tracker  became fully operational; at times there were even more than the 24 planned satellites (due to some long-lasting Block-I satellites). We have also seen that AntiSpoofing (AS) had little effect on the high accuracy interferometric applications of the GPS if modem rec...

True navigation, which provides the user with detailed instructions on how to reach a specific destination, is one of the fastest-growing areas in intelligent vehicle technology. Navigation devices utilize map-matching and best-path algorithms, along with userdefined filtering, to allow the user to choose between the fastest or most direct route to a desired destination. Some systems even allow the user to indicate specific routes to be avoided. The map databases used all provide basic mapping information (streets, major landmarks, etc.), but can also include points of interest and/or helpful location information (restaurants, etc.), depending upon their level of detail and how often they are revised.   Autonomous navigation devices range from in-dash units that are small enough to fit into a 1-DIN slot, to multi-component systems with CD-ROM changers and large multi-plane colour displays. The price of these systems can vary from a few hundred dollars to several thousand doll...

Additional techniques are being developed for increasing the accuracy of the positioning information derived from the GPS for certain applications. One technique, which has been developed by the US Federal Aviation Administration (FAA), uses transmissions from communication satellites to improve the positioning accuracy of GPS tracking device in aircraft. This technique, known as the wide area augmentation system (WAAS), uses a network of wide area ground reference stations (WRS) and two wide area master stations (WMS) to calculate pseudorange correction factors for each SV, as well as to monitor the operational health of each SV. This information is uplinked to communication satellites in geostationary earth orbit (GEO), which transmit the information on the L1 frequency, along with additional ranging signals. This system has improved the positioning accuracy of GPS on board aircraft to within 7 metres horizontally and vertically, allowing the system to be used by aircraft for Catego...

Calibration Electronic compasses need to be calibrated whenever you change batteries. If your  GPS Tracking Device  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. (The rough-and-ready rule is that if barometric pressure is falling, bad weather is on the way; if it’s rising, clear weather is coming.) 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...

Applications requiring positioning in mobile networks have gained importance in recent years. Examples include not only LBSs, but also enhanced emergency call services such as the North American E911 and the newly defined Emergency Call (eCall), which is planned to become a European standard as part of the eSafety initiative of the European commission. Mobile network providers already offer LBSs along with positioning, although the accuracy and reliability of the present techniques do not yet meet the requirements of such services in all cases. One of the most popular positioning systems in navigation is the GPS tracker , which is satellite based, widely available and quite accurate, as long as the receiver to be localized and the satellites have an LOS connection. Since most common mobile phones do not support the GPS, network providers evaluate the position of the network’s base stations (BSs) which have connections to the mobile stations (MSs) to be located. The accuracy of the pr...

Despite similarities, there are some issues in the consistency GNSS issues as you know. For example, you may recall that the roll out of the new systems is not coordinated. In other words GPS ( GPS Tracking Device  ) Modernization, GLONASS replenishment, and QZSS and Galileo deployment have not been synchronized. Despite much cooperation there is no clear agreement among nations that launches and operational capabilities of GLONASS, GALILEO, GPS, QZSS, and Beidou will happen in the same time frame. Also there are differences between GLONASS and GPS regarding CDMA and FDMA. There are also differences in the time standards between the two systems. Not to mention the overlap between the GPS M-code and Beidou. It is important that these inconsistencies are worked out technologically because apart from the less sophisticated applications for GNSS interoperability will be required. For the full potential of the system to realize multiple GNSS, frequencies will need to work together. In...

Since the first generation GPS chip was presented to the public, it overcomes some problems: unclear signal of ex-chip, long positioning time, location drifting, etc. Due to the progress of chip manufacturing procedure and size reduction, even PDA, digital camera, cell phone and so on can be integrated with GPS. The personal vehicle tracking devices equipped on the vehicles is simple and more accuracy than dead reckoning method. It is getting to be used as basic vehicle equipment. Conversely, some disadvantages of GPS still need to be addressed. For example, if a cell phone or radio’s wave band is closed to GPS’, it would cause interference. In addition, tunnels and weather would affect the accuracy of GPS also. Thus, adjusting GPS error by a fixed base station and then conveying it to the vehicles’ GPS for correcting can add accuracy. It is called Differential GPS (namely D-GPS). The FM radio can also receive the positioning signal from the base station. Vehicle Tracking The GPS ...

So what is coming? Some day there may be as many as 80 satellites from GPS, GLONASS, GALILEO, QZSS, and others. If so the systems will provide users with a variety of signals and codes. The availability of many more satellites will enable new applications in areas where the current lack of satellites has been a hindrance. For civil users, Personal GPS tracker will provide more protection from interference, ability to compensate for ionospheric delays with pseudoranges, and wide-laning or even trianing capabilities. For military users, there will be greater antijam capability and security. For everybody, there will be improvement in accuracy, availability, integrity, and reliability. It looks as if the GNSS is on its way. So it is no surprise that there is great anticipation from a business perspective, but from a user’s point of view the situation is not unlike the advent of GPS more than 30 years ago. Much is promised but little assured. New capabilities will be available, but exac...

The Federal Geodetic Control Committee (FGCC) has written provisional accuracy standards for GPS relative positioning techniques. The older standards of first, second, and third order are classified under the group C in the new scheme. In the past, the cost of achieving first-order accuracy was considered beyond the reach of most conventional surveyors. Besides, surveyors often said that such results were far in excess of their needs anyway. The burden of the equipment, techniques, and planning that is required to reach its 2σ relative error ratio of 1 part in 100,000 was something most surveyors were happy to leave to government agencies. But the FGCC’s proposed new standards of B, A, and AA are respectively 10, 100, and 1000 times more accurate than the old first-order. The attainment of these accuracies does not require corresponding 10-, 100-, and 1000-fold increases in equipment, training, personnel, or effort. They are now well within the reach of private GPS surveyors both econo...