Land vehicle navigation system
First Claim
1. A land vehicle navigation system comprising:
- a global positioning system (GPS) for receiving and demodulating signals from a plurality of satellites to fixedly determine the present travelling position of a vehicle;
a satellite position computing means for determining the position of each of said satellites, based on almanac data supplied from said global positioning system;
a heading detector for continuously detecting the heading of said vehicle;
a geographical information means for storing a map indicated on an area in which the vehicle is to run and data representative of the distribution of the building height at said area;
a visibility computing means for determining the visibility for signals from each of the satellites, based on signals indicative of the position of each satellite from said satellite position computing means, data representative of the heading of the vehicle from said heading detector and data indicative of the distribution of the building height from said geographical information means;
a satellite selecting means for selecting a combination of satellites providing the maximum visibility at said area, based on signals indicative of the visibility from said visibility computing means; and
a map and present position displaying means for displaying data representative of the map from said geographical information means and the present position of the vehicle,whereby a combination of satellites providing the maximum visibility for signals to be received by said global positioning system can be selected depending on the distribution of the building height in the area in which the vehicle is running.
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Accused Products
Abstract
A land vehicle navigation system is adapted to display the present position of a vehicle by receiving signals from a combination of satellites under the global positioning navigation system. The present position of the vehicle is displayed on a screen, superposed over map data. To obtain the best global positioning data, the combination of satellites is selected in connectio with the visibility. To perform the positive reception of signals from the satellites as the vehicle is running in an urban area, data relating to the building height around the area can be obtained from a geographical information section including data indicative of the map and the building height distribution with respect to the area to determine the visibility.
136 Citations
19 Claims
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1. A land vehicle navigation system comprising:
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a global positioning system (GPS) for receiving and demodulating signals from a plurality of satellites to fixedly determine the present travelling position of a vehicle; a satellite position computing means for determining the position of each of said satellites, based on almanac data supplied from said global positioning system; a heading detector for continuously detecting the heading of said vehicle; a geographical information means for storing a map indicated on an area in which the vehicle is to run and data representative of the distribution of the building height at said area; a visibility computing means for determining the visibility for signals from each of the satellites, based on signals indicative of the position of each satellite from said satellite position computing means, data representative of the heading of the vehicle from said heading detector and data indicative of the distribution of the building height from said geographical information means; a satellite selecting means for selecting a combination of satellites providing the maximum visibility at said area, based on signals indicative of the visibility from said visibility computing means; and a map and present position displaying means for displaying data representative of the map from said geographical information means and the present position of the vehicle, whereby a combination of satellites providing the maximum visibility for signals to be received by said global positioning system can be selected depending on the distribution of the building height in the area in which the vehicle is running. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A land vehicle navigation system comprising:
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a global positioning system (GPS) for receiving and demodulating signals from a plurality of satellites to fixedly determine the present travelling position of a vehicle; a satellite position computing means for determining the position of each of said satellites, based on almanac data supplied from said global positioning system; a heading detector for continuously detecting the heading of said vehicle; a geographical information means for storing a map indicative of an area in which the vehicle is to run and data representative of the distribution of the building height at said area; a visibility computing means for determining the visibility for signals from each of the satellites, based on signals indicative of the position of each satellite from said satellite position computing means, data representative of the heading of the vehicle from said heading detector and data indicative of the distribution of the building height from said geographical information means; a PDOP (HDOP) computing means in response to signals indicative of the positions of the satellites from said satellite position computing means and for computing PDOP representative of radial range error with respect to the three-dimensional coordinates determined from a combination of satellites or HDOP representative of radial range error in the two-dimensional coordinates; a satellite selecting means for determining a combination of satellites providing the minimum PDOP (or HDOP) from data obtained from said geographical information means and representative of the average building height in an area in which the vehicle is presently travelling, for determining a combination of satellites providing the maximum visibility in said area from signals indicative of the visibility form said visibility computing means and for selecting said two combinations in accordance with a given basis; and a map and present position displaying means for displaying map data from said geographical information means and data indicative of the present position of the vehicle from said global positioning system; whereby a combination of satellites providing signals to be received by said global positioning system can be selected on the basis of both the PDOP (or HDOP) and visibility data, depending on the distribution of the building height in the area in which the vehicle is running. - View Dependent Claims (9, 10, 11, 12)
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13. A land vehicle navigation system comprising:
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a geographical information means for storing a map indicative of an area in which the vehicle is to run and data representative of the distribution of the building height in said area; a heading detector for continuously detecting the heading of a vehicle; a global positioning system (GPS) navigation means comprising a global positioning system (GPS) for receiving and demodulating signals from a plurality of satellites to perform a computation of positional measurement for determining the present position of said vehicle, a satellite position computing means for determining the position of each of said satellites from almanac data obtained through said global positioning system, visibility computing means for determining the visibility for signals from each of said satellites, based on signals indicative of the position of the satellite from said satellite position computing means and data representative of the heading of said vehicle movement from the heading detector and data indicative of the distribution of the building height from said geographical information means, and satellite selecting means for selecting a combination of satellites providing the maximum visibility in the area, based on signals representative of the visibility from said visibility computing means; a dead reckoning system for computing actual travelling locus of the vehicle to determine the present position of the vehicle; a GPS or dead reckoning selector for storing the respective present positions of the vehicle obtained by said GPS navigation means and dead reckoning system and for outputting data indicative of the vehicle position under the optimum condition; and a map and present position displaying means for displaying map data from said geographical information means and the present position of the vehicle from said GPS or dead reckoning selector, whereby the optimum one of the positional data obtained by both the GPS navigation means and dead reckoning system can be selected and, when it is wanted to obtain positional data from said GPS navigation means, a combination of satellites providing the maximum visibility can be selected in consideration with the visibility. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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Specification