Communications: radio wave antennas – Antennas – Slot type
Reexamination Certificate
2001-07-06
2003-08-12
Clinger, James (Department: 2821)
Communications: radio wave antennas
Antennas
Slot type
C343S702000
Reexamination Certificate
active
06606072
ABSTRACT:
STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
REFERENCE TO A “SEQUENCE LISTING,” A TABLE, OR A COMPUTER PROGRAM LISTING APPENDIX SUBMITTED ON A COMPACT DISK
Not applicable.
BACKGROUND OF THE INVENTION
The present invention relates to antennas for receiving GPS signals. In particular, the present invention relates to GPS antennas that are optimized for use in proximity to a human body.
Navigation is key to national and international industry, commerce, and safety. Knowledge of position, both relative and absolute has been used throughout history to gain tactical advantage in both peaceful and not so peaceful pursuits. From the rudimentary techniques developed over two millennia ago, people all over the world have made both evolutionary and revolutionary progress in the business of knowing their position. Navigation progressed from simple piloting—the art of connecting known points—to satellite-based navigation systems.
Today the premier worldwide navigation solution is the Global Positioning System (GPS). This satellite-based navigation system was developed by the Department of Defense (DoD) to support a variety of military operations. This system has been used in a variety of civilian systems. As the adoption of satellite-based navigation technology has grown since its introduction in the early 1980's, so has the number and complexity of devices for personal navigation and location. GPS is broken down into three basic segments, as follows: 1) space—comprising the satellites; 2) control—incorporating tracking and command centers; and 3) user—performing navigation functions based on ranging to the satellites.
The space segment contains the GPS Space Vehicles (SVs) placed in circular orbits with 55° inclination and a semi-major axis of 26,560 km (20,182 km altitude) corresponding to an orbital period of 12 hours sidereal. There are six orbit planes placed at 60° offsets in longitude with nominally four satellites in each plane, giving 24 satellites. Currently there are 28 active satellites in the planes. Spacing within the plane is adjusted to achieve optimal coverage over regions of interest. The satellites themselves are three-axis stabilized and use solar panels to provide power. Each satellite contains a pair of atomic clocks (for redundancy) which have a stability of 1 part in 10
13
. Each satellite broadcasts on two frequencies, 1575.42 MHz (L
1
) and 1278.6 MHz (L
2
). The L
1
signal contains two separate pseudo-random noise (PRN) modulations: 1) the Clear Acquisition (C/A) code at bit or ‘chipping’ rate of 1.023 MHz (i.e., each millisecond there are 1023 modulated bits or ‘chips’ transmitted); and 2) the so-called ‘P’ code which has a chipping rate of 10.23 MHz or 10 times that of the C/A code. The L
2
signal only contains the P code. GPS uses a PRN coding sequence of bits that have a specified length but have the property that different codes do not strongly correlate with one another (i.e., they are orthogonal). The C/A code is 1023 chips long and thus repeats every 1 millisecond. The full P code length is 38 weeks but is truncated to 1 week.
The control segment is responsible for the operation and maintenance of the GPS. There are five monitoring stations worldwide at Kwajalein, Hawaii, Colorado Springs, Diego Garcia and Ascension. These stations measure the discrepancies between the satellite state information (satellite positions and clock) as well as health of the satellites. The Master Control Station (MCS) in Colorado Springs formulates predicted values and uploads them to the satellites. This data is then included in the new message for broadcast to the users.
The user segment comprises GPS receivers that decode the satellite messages and determine the ranges to at least four GPS SVs to determine 3-dimensional position and the receiver clock offset. Users breakdown into two main groups: authorized and unauthorized. Authorized users have full access to both the C/A and P codes. Authorized users are restricted to the military and other special groups or projects with special permission from the DoD. Unauthorized users generally cannot access the P codes as the code itself is encrypted before broadcast by a process known as anti-spoofing (AS). This makes the process of emulating a GPS signal to the authorized user more difficult. The encrypted modulated signal is known as Y code. Additionally the hand-over-word (HOW) between the C/A and Y code is also encrypted. Authorized users are given a ‘key’ that allows for the decryption of the HOW as well as the Y code. Authorized user receiver equipment with dual frequency code access uses what is known as the Precise Positioning Service (PPS).
GPS receivers are very sensitive devices capable of measuring the low signal levels available on, or near, the surface of the Earth. A GPS receiver design incorporates radio-frequency (RF) elements, signal downconversion, signal sampling, digital signal processing, as well as computational devices and methods. The first element of the GPS receiver that interacts with the satellite signal is the antenna. The antenna is a RF component that converts the signal present in the air to an electrical signal which is processed by the receiver.
There are many aspects that are important in antenna design that include, but are not limited to, the following: 1) frequency or frequencies of maximum sensitivity; 2) polarization; 3) size; 4) shape; 5) bandwidth; and 6) gain pattern. Depending on the goals of a particular GPS receiver, various antenna design aspects are emphasized or de-emphasized.
Given the above general background of GPS, a variety of GPS receivers have been developed to fill various market niches. One of these markets is personal GPS.
In the early 1980's, exercise began to play an increasingly important role in the daily lives of a growing segment of our society. As our economy has prospered, many of these individuals have developed into serious athletes and have helped create a thriving environment of competitive amateur athletics. These athletes represent a focused and competitive segment of our society and are devoted to their performance and to monitoring and measuring their workouts. They need systems, methods, and devices to assist in performing these tasks.
Even the most competitive and focused of athletes only have crude approximations of their performance. They typically use a stopwatch to measure the time of their activity and then estimate the average pace based on the estimated course length. This system and method only works well over a measured course, something that rarely occurs for most athletes. They can also use a heart monitor to track their exertion. Recreational athletes, who are concerned more with health and fitness than with competitive considerations, also desire quantitative feedback about their performance. However, these methods of providing performance feedback remain imprecise and unsatisfying to athletes of all types.
The idea of directly attaching a device capable of receiving and processing GPS signals to an athlete has been theorized in several quarters. By doing so, the above-discussed feedback, as well as many other performance parameters, could be virtually instantaneously provided to an athlete.
However, such a directly-attached device, if comprised solely of prior art components, would experience significant difficulty in receiving clear and processable GPS signals. Such difficulty is directly attributable to the fact that the antenna of such a device would be excessively sensitive to gain variations when in the proximity of a human body. In essence the body blocks the majority of the signal. In addition, such a prior art antenna that may incorporate patch elements or micro-strips may be excessively sensitive to the location of a GPS signal source.
The above description relates to problems and disadvantages relating to tracking, logging, and analysis of running activities. The same or similar problems and disadvantages also apply to numerous other athletic activities be
Fuller Richard
Glissman John
Hayward Roger
Marshall Noel
Clinger James
Stata Labs, LLC
Townsend and Townsend / and Crew LLP
LandOfFree
Antenna design using a slot architecture for global... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Antenna design using a slot architecture for global..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Antenna design using a slot architecture for global... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3093738