Articles in the Articles Category

coordinates

Dec 2005 | Comments Off on Geodetic Misunderstanding

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.

Nov 2005 | Comments Off on Beginning of a cycle of innovation GLEN GIBBONS

 

A report on ION GNSS 2005, 13-16 September, Long Beach, USA

 
 

Recent …

Nov 2005 | Comments Off on “Information from Imagery”
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Ian Dowman, President, ISPRS explains …

Nov 2005 | Comments Off on The casualty

 
 
 

October 8, 2005.
The earth quaked again. This time more than 70,000 …

Nov 2005 | Comments Off on Signal propagation through the troposphere
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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 …

Nov 2005 | Comments Off on JAMFEST, A cost effective solution to GPS vulnerability testing
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The 746th Test Squadron (746 TS) has conducted complex GPS jamming experiments since the early 1990s and played a key role “behind the scenes” creating multiple high-profile jamming environments for programs such as the Joint GPS Combat Effectiveness (JGPSCE) exercises and Quick Reaction Tests. These programs, conducted to support real-world operations, enhanced the 746th TS’s ability to recreate realistic jamming environments and resulted in the 746 TS earning the reputation as the recognized experts for open-air GPS vulnerability testing.

Nov 2005 | Comments Off on MARK YOUR CALENDAR

November 2005

 

International Conference: “Earth Observation foaterr vegetation …

Nov 2005 | Comments Off on Indoor positioning in wireless
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Recently mobile location based services (LBS) are provided via a mobile terminal such as a personal digital assistant (PDA), a cellular phone and so on. The location method that searches where the mobile terminal of a user is accurately is a key factor for providing convenient and useful LBS. The most well known method associated with positioning system is GPS. The signal of GPS satellites can be always acquired outdoors and this system provides comparatively accurate location information. However, there are difficulties in applying GPS directly to indoor positioning because of the weakness of signal. And the positioning using the mobile communication signal between a base station and a cellular phone does not provide adequate accuracy due to some technical limitations of communication systems when applied to navigation. In addition, severe multipaths are present in an indoor environment. So a new wireless communication technology is required for indoor positioning to achieve a better and appropriate accuracy. Wireless local area network (LAN) has been installed in a number of indoor areas such as office, terminal, campus, and park with interests in mobile Internet. Therefore, it is expected that a wireless LAN signal would be easily acquired for indoor positioning. Various positioning measurements like time of arrival (TOA), time difference of arrival (TDOA), and received signal strength may be employed for indoor positioning. Employing TOA or TDOA measurements requires a time synchronization between a transmitter and a receiver. But, a time synchronization between a transmitter and a receiver is very difficult if not impossible in a wireless LAN. Therefore, it is more appropriate to use signal strength for indoor positioning with a wireless LAN.

Nov 2005 | Comments Off on Innovations 1983 and 1996
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Tidal Modeling for GPS Positioning –

In …

Oct 2005 | Comments Off on Building relationships
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11th Technology summit strengthens Indo-Canadian relationship. 21-22 September 2005 New Delhi

The 11th Technology Summit and …