B. Satellites for navigation
Satellites provide the necessary information to the navigation system to measure vehicles location. There are about 31 active satellites used for GPS communication, which are rotating around the earth’s axis. Their orbit is inclined 55 degrees with respect to the equator. Satellites are placed at 20,000 km from the earth’s surface. The orbits are designed in such a way that each satellite rotates two orbits per day. Orbits are planned so that at least 6 satellites in view, from most places on the earth [4].
C. Trilateration
Trilateration is a simple mathematical principle used to estimate the vehicle location by calculating the distance from the satellites in view. For 2-D (latitude, longitude) location estimation
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Navigation system works smoothly till it receives the GPS signals. GPS satellites uses UHF band for the signal transmission. Civilian GPS uses 1575.42 MHZ frequency and is designated as L1 GPS band [5]. Satellites transmit GPS signals with power equivalent to a 30-50 watt light bulb. These signals have to cover approximately 20,000 km. when they arrive at receiver, in the best case, signal strength would be around 120 dbm (1 x 10-15 watts). General home Wi-Fi signals are millions of times stronger than this. These signals can suffer an additional degradation of 20-30 dbm in urban conditions, or may be blocked completely [7].
A. Challenges in GPS navigation[9]
Now we will discuss the factors that affect the GPS signals in detail.
• Ionosphere and troposphere delays – GPS signals slows as it passes atmospheric obstacles like clouds, fog etc., resulting in delays at receiver.
• Tall buildings – In urban areas tall buildings are common and can reflect the GPS signals, thereby inducing errors.
• Tunnels and Parking garages – Can result in worst condition where GPS signal is completely lost [8].
• Multi level roads – Multi level roads can confuse GPS receiver. Consider a scenario where there are 4 level roads. If vehicle is in 2nd level, it is difficult for GPS signal to pierce the layer above. This leaves receiver to think which road am I on?
• Dense forest – Dense forests can affect the GPS signals making
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Consequences of lost GPS signals
• Emergency Vehicles –such as Ambulance, Fire engines, Police vehicles can face a serious problem in reaching the incident location quickly.
• Public Transportation –Inaccurate arrival times of buses, trams, trains etc., may cause inconvenience to hundreds of commuters.
• Commercial Transportation – Taxis, logistic firms may face financial crisis due to failure in tracking the goods.
• Unfamiliar Areas – Tunnels and park garages, where probability of losing GPS signal is more, may result in wasted fuel and time.
• Automated Pricing System – These systems may fail due to lack of data which is needed to charge for road usage.
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C. Dead reckoning Loss of GPS signal may lead to hazards like accidents, misguidance etc. Dead reckoning plays a vital role in these situations to aid navigation systems. For vehicles moving on a two-dimensional plane, vehicle position can be calculated at any point of time provided that the initial location and relevant displacement parameters are available. This method of position estimation is often known as Dead-reckoning principle [6]. Dead reckoning requires the last known position of vehicle, direction of vehicle, distance travelled and vehicle altitude for successful approximation of new
and maps, people with cameras. Taxis wait for any minute signal to rush these people to their
Transportation systems are what support the high levels of accumulation and concentration within cities. The bigger the city, the more complex its urban problems are if not properly managed. The largest transportation problems occur when public transportation systems fail to fulfill the many requirements of urban mobility. Urban efficiency is highly dependent on its transportation systems to move consumers, labor, and goods from one point to another. The most outstanding urban transportation issues in the United States are: traffic congestion, longer commuting, inadequacy of public transport, green transportation difficulty, and good distribution (Rodrigue).
...and it may be helpful, but the analysis has not revealed it yet. A speed and curve warning is a different system that uses someone’s GPS. The current GPS system might offer a warning feature if someone will go over the speed limit. More significant examples of GPS based automobile technology are just around the turn. Already being tested in different countries that Europe is the built-in Intelligent Speed Adaptation, which subjects speeding alerts and can also make it harder to press further down on the accelerator or it can even automatically stop the automobile. Taking curves too careless, another common cause of accidents is also the focus of warning device research and field testing. Such a device would warn someone to slow down when a sharp curve coming before it is too late. It is another request of GPS technology that could improve the safety of the driver.
Christopher Columbus was known as a “dead reckoning navigator”[2]. Dead Reckoning Navigation, or also known as Deduced Navigation, was used by an umpteen of sailors. In Dead Reckoning Navigation the helmsman can find his locus by measuring the distance he has sailed to a known point. Each day, the ending position was the starting point for the next day. However, this method is not as elementary as it sounds. In order for this tactic to work, the helmsman needs to measure his course and distance sailed. Therefore, a course is measured by a magnetic compass, and distance with a time and speed calculation. One can conclude then that this was a nettlesome process. Of course, since then humans have immensely improved in this area. Today, there is a way to know where one is at while at sea that is much less problematic.
highway without seeing billboard signs. Checking out at the grocery store can be tricky if trying to avoid
The invention of the GPS started with Dr. Ivan Getting leaving his position at Raytheon Company, and armed with the knowledge of what was at the time the most advanced navigational technology in the world, they began developing the Global Positioning System. He, Roger L. Easton, and Bradford Parkison began in the 60’s with a constellation of 24 satellites (placed in six orbital planes) orbiting the earth at a very high altitude (about
...regarded GPS – an indispensable part of GIS. Discussions on cartographic principles, commercial GIS software programs, satellite images, aerial photos, and geodatabases are some of the other conspicuous omissions in this book. There is an inconsistency in the depth of topics explored; for example map projections are explored in great depth, while vector topology is merely glossed over. These omissions and inconsistencies would in my opinion make this book marginally less beneficial to all the three audiences together. However, there is something for all them; structure for engineers, equations for engineers and students, and GIS concepts for students, engineers and users. This book will therefore be undeniably valuable if used to complement the material in some of the other fundamental GIS books in the discipline. It has merits, but there is room for improvement.
...inding the suited vehicle which is the closest to the emergency. The vehicle number will be logged and informed of the emergency. Along with the patient information and incident to expect sent to the vehicle, the GPS will provide directions from the current location to the patient and quickest path back to the hospital. The GPS will give the hospital personnel an idea of how long it will take the vehicle to get to the hospital and have equipment, room, and personnel ready to help the patient. By taking the quickest path, along with medical personnel being ready for receiving the patient, could mean the difference of life and death depending on the incident.
Finding ways to move goods from one point to another at a reasonable cost and within an acceptable time frame is a growing challenge for global businesses today. The costs and risks associated with transportation are increasing with the advent of globalization and low-cost-country sourcing. Even for companies with local operations only, they have to supply their products to various parts of a country which increases the costs and risks. Since the cost of gasoline has been on an upward trend, high level of efficiency in transportation is required to lower the costs involved and the risks associated with the costs. Costs concepts in transportation include economic, social and accounting costs. The risks and costs involved increases if the various modes of transport are used. There has been concern over many businesses failure to strategically think when they employ multimodal transportation services. Many businesses prefer the least expensive multimodal model instead of choosing the most effective; this trade-off is very expensive with hidden costs and risks increasing significantly (Molenaar, Anderson, Schexnayder, National Research Council (U.S.)., National Cooperative Highway Research Program., American Association of State Highway and Transportation Officials., & United States, 2010).
The use of technology makes our daily tasks easier, such as a better sense of direction while driving via a GPS, safety features in our cars such as Auto Drive and Auto Park. These technologies have made driving an easier and enjoyable experience as well as reducing our chances of getting into accidents. The research presented in the following article “Driven to Distraction [in car technology]” provided surprising conclusions. Professor John D Lee from the University of Iowa states the following issue: “Technology is changing very quickly. Many of these things coming into the car were not designed to be used in it.”(Edwards 8). He proves that there are a lot of in car technologies in today’s society that can demand our full attention without us even knowing, and can lead to tremendous consequences that can become dangerous distractions on the road. Satellite navigation (GPS) makes our lives easier because it can give us the correct directions to a desired address. This is unlike the past where the navigationally challenged would consider it a nightmare to drive to a new location.
The GPS is sensing knowledge to help with navigation with the car and destinations. Autonomous cars are not yet available on a large scale of the world such as out of the United States of America, but have been programmed and developed to travel along the roads of America. Most autonomous cars are programmed only for American roads, we have made a big step towards the future with autonomous cars, with them being only available mainly in America, they are a luxury. They are making their way to larger scale autopilot features, and will eventually be available on a larger scale.(Ali
TVS and telephones are using satellites, and I thought it would be a good idea
There was a time a person would use a roadmap to get from one location to another. Some also would stop and ask for directions. Today, you seldom see paper maps and people stopping at a local gas station for directions. Many vehicles come with a navigation system that provides a real-time map of the vehicle’s current location as well as systematic directions to requested destination.
Transportation system is a dynamic system. Information about traffic must be regularly updated to keep pace with ever-changing transportation system. Data must be collected and analyzed systematically to get representative information.
I go to the same place at least four times a year with my friends. Instead of learning where we are going which is the same route we take every time, We have to use a GPS because our minds don 't pick up the surrounding areas or the road sign because we wait for the GPS to say take the right in 500 feet. As a new driver GPS are great to get around when you live in the country town like me. But the drawback when using a GPS were not learning anything because we choose to technology to get us to our destination instead of our brains. By doing this our brains are getting