NN310 Homework 4 - Global Navigation Satellite Systems (GNSS) EXAM
Questions AND Correct Answers
_____________ is a base reference point for a coordinate system. - ✔✔Datum
__________________ is the process in which LOPs from separate satellites generate a GPS fix. A
minimum of ___________ satellites are needed for a __________ Dimensional fix. - ✔✔Trilateration
4
3
Advantages of GNSS - ✔✔-Highly accurate positional and time information.
-Worldwide, 24hr coverage.
-Errors such as Dilution of Precision (DOP) are known and can be mitigated.
-Multiple systems available internationally providing redundancy.
Because of the vulnerabilities of GNSS, it cannot be solely relied upon. In accordance with NAVDORM,
GNSS positions should be validated periodically by __________ and __________ means. - ✔✔visual
radar
Control Segment - ✔✔-Maintains and updates the operating space segment
-6 Monitor Stations
-1 Master Control Station (MCS)
-4 Ground Stations (Antennas)
Datum's such as the North American Datume (NAD) had a reference position on the _____________ of
the Earth. In order to have a datum system that would fit the majority of the globe, vice just a region, a
Datum had to be referenced at the __________ of the Earth. This would result in the development of
__________84. - ✔✔surface
center
WGS
, Disadvantages of GNSS - ✔✔-Over reliance; GNSS have become critical to trade and infrastructure.
-Loss of GNSS systems would have significant impact to world trade.
-Military have become over reliant, especially in terms of Navigation.
Figure of Merit (FOM) - ✔✔-NAVSTAR GPS accuracy is characterized by Figure of Merit (FOM).
-FOM is a value between 1-9 of which 1 is the most accurate GPS position and 9 the least accurate.
Global Navigation Satellite System (GNSS) - ✔✔A general term describing any satellite constellation that
provides Positioning, Navigation, and Timing (PNT) services on a global or regional basis
-most prevalent GNSS in use is the US NAVSTAR Global Positioning System (GPS)
GNSS accuracy can be augmented and improved from additional networks that are either satellite based
or use ground stations on the Earth's Surface such as: - ✔✔-Wide Area Augmentation Services (WAAS)
-Global Differential GPS
-International GNSS
GPS is critical to infrastructure including: - ✔✔Aviation
Maritime
Public Safety
GPS positions are provided in _______________ and _____________ as the coordinate system with
positions provided in the______________ datum. - ✔✔latitude
longitude
WGS84
GPS satellites transmit on 2 carrier frequencies (L1 / L2) concurrently; they are called C/A and P Code. -
✔✔C/A provides the Standard Positioning Service (SPS); that is a civilian frequency that can be received
and used by all GPS Receivers, civilian or military.
P Code provides the Precise Positioning Service (PPS); that is military frequency that is encrypted and
can only be used by US and allied military GPS receivers loaded with the correct Cryptographic material.
Questions AND Correct Answers
_____________ is a base reference point for a coordinate system. - ✔✔Datum
__________________ is the process in which LOPs from separate satellites generate a GPS fix. A
minimum of ___________ satellites are needed for a __________ Dimensional fix. - ✔✔Trilateration
4
3
Advantages of GNSS - ✔✔-Highly accurate positional and time information.
-Worldwide, 24hr coverage.
-Errors such as Dilution of Precision (DOP) are known and can be mitigated.
-Multiple systems available internationally providing redundancy.
Because of the vulnerabilities of GNSS, it cannot be solely relied upon. In accordance with NAVDORM,
GNSS positions should be validated periodically by __________ and __________ means. - ✔✔visual
radar
Control Segment - ✔✔-Maintains and updates the operating space segment
-6 Monitor Stations
-1 Master Control Station (MCS)
-4 Ground Stations (Antennas)
Datum's such as the North American Datume (NAD) had a reference position on the _____________ of
the Earth. In order to have a datum system that would fit the majority of the globe, vice just a region, a
Datum had to be referenced at the __________ of the Earth. This would result in the development of
__________84. - ✔✔surface
center
WGS
, Disadvantages of GNSS - ✔✔-Over reliance; GNSS have become critical to trade and infrastructure.
-Loss of GNSS systems would have significant impact to world trade.
-Military have become over reliant, especially in terms of Navigation.
Figure of Merit (FOM) - ✔✔-NAVSTAR GPS accuracy is characterized by Figure of Merit (FOM).
-FOM is a value between 1-9 of which 1 is the most accurate GPS position and 9 the least accurate.
Global Navigation Satellite System (GNSS) - ✔✔A general term describing any satellite constellation that
provides Positioning, Navigation, and Timing (PNT) services on a global or regional basis
-most prevalent GNSS in use is the US NAVSTAR Global Positioning System (GPS)
GNSS accuracy can be augmented and improved from additional networks that are either satellite based
or use ground stations on the Earth's Surface such as: - ✔✔-Wide Area Augmentation Services (WAAS)
-Global Differential GPS
-International GNSS
GPS is critical to infrastructure including: - ✔✔Aviation
Maritime
Public Safety
GPS positions are provided in _______________ and _____________ as the coordinate system with
positions provided in the______________ datum. - ✔✔latitude
longitude
WGS84
GPS satellites transmit on 2 carrier frequencies (L1 / L2) concurrently; they are called C/A and P Code. -
✔✔C/A provides the Standard Positioning Service (SPS); that is a civilian frequency that can be received
and used by all GPS Receivers, civilian or military.
P Code provides the Precise Positioning Service (PPS); that is military frequency that is encrypted and
can only be used by US and allied military GPS receivers loaded with the correct Cryptographic material.
