2,1 cấu trúc tín hiệu GPS
Như đã đề cập trong Chương 1, mỗi vệ tinh GPS truyền một tín hiệu vô tuyến lò vi sóng bao gồm hai tần số sóng mang (hoặc sóng sin) được điều chế bởi hai mã kỹ thuật số và một thông báo chuyển hướng (xem Hình 2.1). Hai tần số sóng mang được tạo ra tại 1,575.42 MHz (gọi tắt là nhà cung cấp dịch vụ L1) và 1,227.60 MHz (gọi tắt là nhà cung cấp dịch vụ L2). ...
The Global Positioning System(GPS) is a satellite-based navigation system
that was developed by the U.S. Department of Defense (DoD) in the early
1970s. Initially, GPS was developed as a military system to fulfill U.S. mili-
tary needs. However, it was later made available to civilians, and is now a
dual-use systemthat can be accessed by bothmilitary and civilian users .
This book is written for engineers and scientists who intend to study and understand the detailed operation principles of GPS receivers. The book is at the senior or graduate school level. A few computer programs written in Matlab are listed at the end of several chapters to help the reader understand some of the ideas presented.
Accurate determination of the mobile position constitutes the basis of many new applications. This book provides a detailed account of wireless systems for positioning, signal processing, radio localization techniques (Time Difference Of Arrival), performances evaluation, and localization applications. The first section is dedicated to Satellite systems for positioning like GPS, GNSS. The second section addresses the localization applications using the wireless sensor networks.
The study of the workshops in Jepara involved an initial extensive survey so as to locate all the
workshops. Then we designed a spatial grid to prepare the following intensive survey. It consisted
of sampling these workshops, creating a detailed database on the structure of the wood industry
in Jepara, and subsequently analysing it (Roda and Cadène 2005). The fieldwork was conduced
by a team of 12 surveyors4
and 2 field coordinators5
. They were equipped with motorbikes, global
positioning system (GPS) devices, questionnaires, and computers.
Information Technology, which is one of global competitive technologies in Korea,
was introduced to utilize the production area more efficiently. Chang (2006) has
reported a using of a wireless internet environment and PDA system to exchange real
time information data between the workers. Shin (2006) has presented a prototype of
block tracking system for pre-erection area using of PDA and GPS to chase the location
of each block and to exchange the pre-erection work order.