Interest in the use of Global Navigation Satellite Systems (GNSS) as a main source of navigation reference is increasing. The system employed for such a purpose should be capable of meeting the requirements of air navigation in terms of accuracy, availability, integrity, and reliability. At present, the accuracy requirements for all ?ight categories up to precision approach are summarized in Table 1. The accuracy requirement for Category I can be achieved most of the time using wide area differential systems such as the American “WAAS”, the European “EGNOS”, and the Japanese “MSAS”. The American Federal Aviation Authority (FAA) is developing a Local Area Augmentation System (LAAS) for categories II and III, involving the ?nal and precision approach phases of ?ight. The system includes at least four reference GPS receivers located at each airport, whereby GPS measurements are collected and processed in real time. The computed GPS differential corrections are sent to aircraft via a (VHF) radio link to calculate its location. LAAS preliminary test results have generally demonstrated accuracy of less than 1 meter. However, the percentage of system availability is still under evaluation. The cost of establishing LAAS for major airports is expected to be significant.
1. Spheroid is considered equivalent to an ellipsoid.
2. The longitude at the North or South Pole is zero degree.
3. The Mean Sea Level (MSL), a time-variant “average”, is
considered as time-invariant and time-independent.
4. The measured “dn” along a spirit level loop sum up to zero.
5. Imagine a freely ?owing ocean or sea channel under
a continent and it represents the Geoid.
6. The geoidal undulation or height (N) is equivalent to orthometric height (H).
7. There are “yours” and “mine” geoids. In other words every country has its
own geoid, creating a “political” boundary value problem for gravity.
8. When one has to re-observe at any station, it does not make any
difference so long one is observing within “few” meters.
9. If one asks for and gets a height as “123.4 m”. It is OK to add
zeros at the end, e.g., 123.4000, to make it more accurate.
A report on ION GNSS 2005, 13-16 September, Long Beach, USA
Recent …
Not by technology alone ARVIND SIVARAMAKRISHNAN
GPS surveyed time-invariant sea floor depths for safe navigation MUNEENDRA KUMAR AND GEORGE A MAUL
Reconfigurable software GNSS receiver in multipath environment FABIO DOVIS, MASSIMILIANO SPELAT, PAULO MULASSANO, MARCO PINI
Indoor positioning in wireless LAN JAYWON CHEY, JANG GYU LEE, GYU-IN JEE
JAMFEST, A cost effective solution to GPS vulnerability testing LT COL ERIC LAGIER, CAPT DESIREE CRAIG, PAUL BENSHOOF
Space environmental effects on satellite communication can be considered as related to space segment, ground segment and on the signals propagating through the earth’s lower and upper atmosphere. The atmospheric structure has significant influence on signal propagation. This has definite influence on the data processing methodologies. The specific applications with which are concerned here are …
All roads lead to GIS…
…The Rural Road Development Project
The Rural Road Development Project, Pradhan Mantri Gram Sadak Yojna (PMGSY) is using GIS for planning and decision making. An Online management tool OMMAS is being developed to populate the attribute data for GIS and provide access to the citizens to view status of various rural roads and other related information. Public Works Department Rajasthan is playing leading role in creating GIS data base and implementing the PMGSY Scheme. A customized standalone GIS software GRIMMS to run various queries related with planning of roads is being developed. Web GIS module is also being developed to make the complete system transparent and will allow citizens to access the information in spatial format related with PMGSY. C-DAC Pune is providing the technical assistance. Submitted by K.K.Mishra, mishra09720@itc.nl
OS seeks partners for GPS correction service
Ordnance Survey is offering Licensed Partners and other interested parties the chance to develop positioning services based on a revolutionary national framework for correcting signals from orbiting satellites. OS Net is a network of more than 80 GPS base stations designed to enable different levels of improved real-time accuracy from the Global Positioning System (GPS) anywhere in Great Britain. OS Net is already delivering efficiencies for Ordnance Survey field staff where it is enabling centimetre-level positioning for their data-collection operations. Now, Ordnance Survey is planning to make the service publicly available through a tier of partner organisations. www.ordnancesurvey.co.uk/business/technical/osnet.html
(5.00 out of 5)