Communications: directive radio wave systems and devices (e.g. – Directive – Including a satellite
Reexamination Certificate
1998-08-11
2001-07-10
Phan, Dao (Department: 3642)
Communications: directive radio wave systems and devices (e.g.,
Directive
Including a satellite
C342S357490, C342S196000
Reexamination Certificate
active
06259399
ABSTRACT:
This application is also related to and hereby claims the benefit of the filing date of a provisional patent application by the same inventor, Norman F. Krasner, which application is entitled Low Power, Sensitive Pseudorange Measurement Apparatus and Method for Global Positioning Satellites Systems, Ser. No. 60/005,318, filed Oct. 9, 1995.
FIELD OF THE INVENTION
The present invention relates to GPS receivers and methods of tracking objects using GPS receivers and to garments containing GPS receivers.
BACKGROUND OF THE PRESENT INVENTION
GPS receivers with multiple GPS antennas are known in the prior art. Examples of such systems are described in U.S. Pat. Nos. 5,341,301; 5,185,610; and 5,177,493. In these systems, dedicated serial correlating hardware is coupled to each GPS antenna That is, for each GPS antenna, there is corresponding serial correlator hardware. Thus, when a GPS receiver includes several GPS antennas, there will be considerable additional hardware required for each GPS antenna. This additional hardware adds to the cost and weight of such a system. Therefore, such systems are not favored despite the fact that multiple GPS antennas tend to improve the performance of GPS receivers due to the problems from partial or complete blockage of GPS signals which plague GPS receivers.
GPS antennas, because of the blockage problem, tend to be mounted in such a way that they protrude from the device or object which carries the receiver. In this way, the antenna can have an unobstructed view of the sky and any GPS satellites in view at any particular time. Consequently, it is possible to place a GPS receiver in a backpack and mount the antenna as a rigid post on the back of the backpack to provide an unobstructed view of the sky. However, no GPS receivers have been placed in garments along with the GPS antenna, such as the flexible strip antenna on the garment.
The combination of GPS systems and other communications is receiving considerable interest, especially in the areas of personal and property tracking. An example of such a combination is shown in U.S. Pat. No. 5,225,842. The communication link allows a GPS receiver located on a mobile person or object to transmit its accurately determined position to remote locations which monitor this activity. Applications of the technology include security, truck fleet tracking, emergency response, inventory control, etc. The prior art has performed such combinations by mating separate GPS receivers and communication systems using suitable electronic interfaces between the two, for example, serial communication ports, etc. Moreover, these systems use conventional serial correlating approaches to acquiring and tracking GPS satellite signals.
SUMMARY OF THE INVENTION
The present invention provides a GPS receiver having multiple GPS antennas which are coupled to one digital memory or several digital memories in order to store digitized signals which are obtained through the multiple GPS antennas. A digital processor is coupled to the digital memory or memories in order to process the digitized signals. When an embodiment of the present invention includes two GPS antennas which provide first and second digitized signals, the digital processor will typically process the first digitized signals to provide a first position information, such as a pseudorange, and process the second digitized signals to provide a second position information. Then, the processor will typically determine which position information has the lower error and select that position information as the proper position information which indicated the position of the GPS receiver.
In a typical embodiment of the present invention, the digital processor will process the first and second digitized signals by performing fast convolution operations. In one embodiment, the digital processor will perform a preprocessing operation on the first digitized signals to provide first results for the first digitized signals and perform a fast convolution operation on the first results to provide second results for the digitized signals and then perform a post processing operation on the second results to provide a third result for the first digitized signals which may then be used to provide a pseudorange from the first digitized signals. Similarly, these operations are also performed on the second digitized signals and a comparison is made between the results obtained from the first digitized signals and the second digitized signals in order to select the position information having the lower error.
In one embodiment of the present invention, selected position information is then transmitted through a transmitter which is typically coupled to the digital processor and a communication antenna. This transmitted position information is received at a base station which may then be used to track the GPS receiver. As described in more detail below, the collection of the GPS signals through the multiple GPS antennas may occur sequentially in time or concurrently in time depending on the architecture of the GPS receiver. The collection concurrently of GPS signals through multiple GPS antennas will typically require several digital memories each concurrently receiving digitized signals from its corresponding GPS antenna.
The present invention also provides a garment, such as a jacket or pants, which includes a GPS antenna and a GPS receiver along with a communication antenna and a communication transmitter. In one embodiment a first GPS antenna is attached to the garment, and a GPS receiver may also be attached to the garment and is coupled to the first GPS antenna A communication antenna may also be attached to the garment and a communication transmitter is coupled to the communication antenna and to the GPS receiver. In one embodiment of the garment of the present invention, a second GPS antenna is also attached to the garment and is also coupled to the GPS processor. In one embodiment, both the first GPS antenna and the second GPS antenna are flexible strip antennas which are substantially coplanar with the surface of the garment. The first and second GPS antennas may be attached to the garment by sewing the antennas to the garment. Often, the GPS antennas will be concealed in the garment or at least not readily apparent upon viewing the garment. The GPS receiver and communication transmitter need not be attached to the garment For example, either the GPS receiver or the communication transmitter (or both) may be attached to a belt which is near the garment, and the GPS receiver and/or communication transmitter is coupled to its corresponding antenna through a flexible conductor.
In a typical embodiment, the GPS receiver in the garment will include a digital memory which is coupled to the GPS antenna to receiver digitized signals obtained through the GPS antenna and will further include a digital processor coupled to the digital memory to process the digitized signals, usually by performing fast convolutions, to provide position informations. The position information may be a pseudorange which is then transmitted by the communication transmitter through the communication antenna
In a typical embodiment, the garment may also include a communication receiver which is coupled to the GPS receiver. This communication receiver may receive satellite data information, such as satellite Doppler information and may receive GPS positioning commands which cause the GPS receiver to determine the position of the receiver or to determine a pseudorange. The communication receiver need not be attached to the garment; for example, this receiver may be attached to a belt which is near the garment, and this receiver is coupled to an antenna which may be on the receiver or on the garment.
A method of tracking an object is also described as another aspect of the present invention. This method includes obtaining at the object a positioning command, and as a result receiving first GPS signals through a first GPS antenna on the object. First digitized samples of the first GPS signals are stored in a digital memory
Blakely & Sokoloff, Taylor & Zafman
Phan Dao
SnapTrack, Inc.
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