每日彙整: 2016-12-02

樹莓派、樹莓派之學習、樹莓派之教育

飛行派工作日誌《八》

選擇一個應用系統的部件，假使只靠一句市場『行話』

66 channel GPS

，恐怕不靠譜的吧？？

如果真是專業『術語』，就得了解其中之『眉角』的了！！

Adafruit Ultimate GPS Breakout – 66 channel w/10 Hz updates – Version 3

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Description

New! Version 3 comes with the latest module which has external antenna support and Pulse-Per-Second outputWe carry a few different GPS modules here in the Adafruit shop, but none that satisfied our every desire – that’s why we designed this little GPS breakout board. We believe this is the Ultimate GPS module, so we named it that. It’s got everything you want and more:

  • -165 dBm sensitivity, 10 Hz updates, 66 channels
  • 5V friendly design and only 20mA current draw
  • Breadboard friendly + two mounting holes
  • RTC battery-compatible
  • Built-in datalogging
  • PPS output on fix
  • Internal patch antenna + u.FL connector for external active antenna
  • Fix status LED

…all for under $40!

The breakout is built around the MTK3339 chipset, a no-nonsense, high-quality GPS module that can track up to 22 satellites on 66 channels, has an excellent high-sensitivity receiver (-165 dB tracking!), and a built in antenna. It can do up to 10 location updates a second for high speed, high sensitivity logging or tracking. Power usage is incredibly low, only 20 mA during navigation.

 

知道『全球定位系統』

Global Positioning System

The Global Positioning System (GPS), also known as Navstar GPS[1][2][3] or simply Navstar,[4] is a global navigation satellite system (GNSS) that provides geolocation and time information to a GPS receiver in all weather conditions, anywhere on or near the Earth where there is an unobstructed line of sight to four or more GPS satellites.[5] The GPS system operates independently of any telephonic or internet reception, though these technologies can enhance the usefulness of the GPS positioning information. The GPS system provides critical positioning capabilities to military, civil, and commercial users around the world. The United States government created the system, maintains it, and makes it freely accessible to anyone with a GPS receiver. However, the US government can selectively deny access to the system, as happened to the Indian military in 1999 during the Kargil War.[6]

The GPS project was launched in the United States in 1973 to overcome the limitations of previous navigation systems,[7] integrating ideas from several predecessors, including a number of classified engineering design studies from the 1960s. The U.S. Department of Defense (DoD) developed the system, which originally used 24 satellites. It became fully operational in 1995. Roger L. Easton, Ivan A. Getting and Bradford Parkinson of the Applied Physics Laboratory are credited with inventing it.[8]

Advances in technology and new demands on the existing system have now led to efforts to modernize the GPS and implement the next generation of GPS Block IIIA satellites and Next Generation Operational Control System (OCX).[9] Announcements from Vice President Al Gore and the White House in 1998 initiated these changes. In 2000, the U.S. Congress authorized the modernization effort, GPS III.

In addition to GPS, other systems are in use or under development, mainly because of a potential denial of access and potential monitoring by the US government. The Russian Global Navigation Satellite System (GLONASS) was developed contemporaneously with GPS, but suffered from incomplete coverage of the globe until the mid-2000s.[10] GLONASS can be added to GPS devices which makes more satellites available and enabling positions to be fixed more quickly and accurately, to within 2 meters [11] There are also the planned European Union Galileo positioning system, China’s BeiDou Navigation Satellite System, the Japanese Quasi-Zenith Satellite System, and India’s Indian Regional Navigation Satellite System (NAVIC).

gps24goldensml

A visual example of a 24 satellite GPS constellation in motion with the earth rotating. Notice how the number of satellites in view from a given point on the earth’s surface, in this example in Golden CO (39.7469° N, 105.2108° W), changes with time.

 

之『字典意義』並不困難。若想深入『理論與實務』，還是上堂 Eric Calais  教授之『 GPS 大地測量』課比較好的也☆

GPS Geodesy

mongolia gps

In the late 90’s, space-based geodetic techniques such as the Global Positioning  System (GPS) reached a level where millimeter-level positioning became achievable globally. In geophysics, GPS measurements have been widely used over the  past decade to monitor crustal displacements, with precision levels on the  order of a few mm/yr now routinely achieved.

In addition to science applications, GPS has become an essential part of the infrastructure of today’s society and represents a significant commercial and job market. Application range from surveying, navigation, transportation, GIS, to geophysics. GPS is now one of several positioning systems grouped under the “Global Navigation Satellite System” (GNSS).

This course will provide a fundamental understanding of the theory and practice of GNSS, with an emphasis on high-precision applications using GPS. Other space geodetic techniques (VLBI, SLR, DORIS) will be mentioned and reference frame issues will be addressed.

The labs will provide hands-on experience in field and data processing techniques, including programming a simple GPS data processing software  and learning to use a high-end research software (GAMIT). Prerequisites are working knowledge of Matlab (or fluency in a programming language such as C or Fortran), and a course in linear algebra.

Lectures