Data processing: vehicles – navigation – and relative location – Navigation – Employing position determining equipment
Reexamination Certificate
1999-11-01
2003-03-04
Beaulieu, Yonel (Department: 3661)
Data processing: vehicles, navigation, and relative location
Navigation
Employing position determining equipment
C701S004000, C701S214000, C073S17800T
Reexamination Certificate
active
06529827
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to an electronic navigation device. More particularly, the present invention is directed to a handheld electronic navigation device, having combined in a single handheld housing a GPS unit, an electronic compass, and an altimeter.
2. Description of the Related Art
Handheld navigation devices are well known, widely used, and are becoming increasingly popular. For example, GPS units, which have the ability to calculate a position and display map, route, and location information are becoming increasingly popular. Conventional GPS units also have the ability to calculate a user's heading, or direction of travel, by determining the movement of a user over time. However, conventional GPS units are unable to determine heading or direction information when the user of the GPS device is not traveling at a sufficient speed, typically in the order of 4 mph or greater.
Accordingly, an outdoor enthusiast (such as a hiker or biker), being often at a standstill or traveling less than a sufficient speed, must typically carry additional instruments, such as a compass, in order to instantaneously determine direction or heading information. Furthermore, it is often additionally desired by such enthusiasts to have knowledge of altitude information. Retaining this information requires yet an additional instrument, such as an altimeter. Carrying multiple such devices is particularly cumbersome when hiking or biking.
In an attempt to overcome the foregoing, one available product combines a GPS unit and a barometric pressure sensor in the same housing. However, the pressure sensor is used only to augment GPS derived altitude information, not as a separate indicator of altitude. Another available product, the XL1000 by SILVA combines a GPS unit and an electronic compass, but not an altimeter.
Additionally, it would be desirable in a navigation unit to include extensive mapping information, and provision for uploading even additional map information as desired. Furthermore, it would be desirable for any such unit to have convenient options for calibrating the altimeter. In this regard, it is well known to calibrate an altimeter with known altitude information input by a user. It is also known, such as in a product known as the “Freestyle Altimeter Watch”, to permit storage in a memory of two known altitudes, such that when a user is in one of the two locations, the correspondingly stored altitude information may be recalled for calibrating the altimeter. While useful, this approach is limited to a pair of locations and, as with other known approaches, requires user input.
Accordingly, the need exists for an improved navigation unit. Particularly, the need exists for a portable navigation unit having GPS, compass, and altimeter outputs. The present invention fills the foregoing identified needs, and other needs, while overcoming the drawbacks of the prior art.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved navigation unit.
It is an object of the present invention to combine prior art navigation units of various types into a single unit capable of individually or simultaneously displaying navigation information for a variety of types of single display.
It is a further object of the invention to provide unique options for calibrating an altimeter.
These and other objects are achieved by a portable, handheld navigation unit having an internal processor. Connected to the processor are, at a minimum, an input (such as a keypad), a display, a memory, a tilt sensor, magnetic sensor, a barometric pressure sensor, and a GPS receiver, which also connects to an antenna, such as a GPS patch antenna. These components, along with a power supply (such as batteries) are housed within a plastic housing sized to be handheld. As will be understood and appreciated, the input and display are accessible at an exterior of the housing, in a conventional manner.
The navigation device of the present invention serves as a GPS unit, in that GPS signals from a plurality of satellites may be received by the GPS receiver, such that the processor calculates position information based upon the received signals. Additionally, map information stored in memory may be retrieved and displayed on the display along with the calculated position information. Additionally, as will be understood and appreciated, the memory may include stored route, forward path, or backward path information, which may be recalled for display on the display. The conventional use and operation of GPS units is well known, and need not be further described.
Additionally, the navigation device of the present invention serves as an altimeter. In particular, the barometric pressure sensor measures barometric pressure and provides the sensed barometric pressure information to the processor. The processor, utilizing stored software, then converts the measured pressure into an altitude, which may be displayed to the user on the display. The conversion of barometric pressure to altitude may be accomplished in any desired and conventional manner. For example, a lookup table may be provided in the memory, where the table contains altitude information corresponding to known barometric pressures. Thus, an altitude corresponding with a sensed barometric pressure may be retrieved from memory and displayed on the display. Alternatively, the preferably, altitude (or elevation) may be calculated using a known equation.
Because barometric pressure in a particular area changes with changing weather, it is necessary for the navigation device of the present invention to be periodically calibrated. In accordance with an aspect of the invention, calibration is accomplished by supplying a known altitude in a particular area to the instrument software so that a correction factor correlating current pressure to known altitude can be generated. In the absence of such a calibration, any change in pressure will be perceived by the processor as a change in altitude, even if it is the result of a change in weather (such as a cold front passing through the particular area in which the device is being used).
In accordance with the principles of the present invention, there are three manners in which the known altitude can be supplied to the instrument software of the navigation device of the present invention for calibration purposes. The first manner of calibration involves calibration by the user. In this case, the user of the navigation device places the device into a calibration mode utilizing the input, and enters the current, known altitude. The processor then generates a correction factor corresponding to the entered altitude information.
In the absence of user input data, the instrument software of the navigation device of the present invention may obtain altitude information from a topographical map stored in the memory and/or displayed on the display. When this manner of calibration is utilized, the GPS unit has acquired a sufficient number of satellite signals, and has determined a position of the device. A map corresponding to the area in which the navigation device is being used, is retrieved from memory and displayed on the display. Thus, with knowledge of the position of the GPS unit relative to the stored topographical map, the altitude is determined since that information is provided in the topographical map information.
In the event a topographical map is not stored in memory and/or displayed on the display of the navigation device (or in the event altitude information corresponding to the location of the unit is not stored in memory), and the user has not entered an altitude using the input of the device, the necessary correction factor can be calculated by the processor using GPS-derived altitude. In this regard, and as will be readily appreciated, the position of a GPS unit in three dimensions may be determined when at least four satellite signals are received and processed. While GPS-derived altitude will typically not be as accurate as the in
Beason Lawrence W.
Burgett Scott
Laverick David J.
Olivier Tracy
Beaulieu Yonel
Garmin Corporation
Rolf Devon A.
LandOfFree
GPS device with compass and altimeter and method for... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with GPS device with compass and altimeter and method for..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and GPS device with compass and altimeter and method for... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3043503