GPS Part 2 Flashcards
GPS comprises three segments:
- The Space Segment
- The Control Segment and
- The User Segment
An SV will be masked (that is not selected for navigation use) if its elevation is less than _°
above the horizon
An SV will be masked (that is not selected for navigation use) if its elevation is less than 5°
above the horizon
Explain the format of SV signals:
SV’s broadcast PRN codes of one millisecond on two frequencies in the UHF band, as well as a NAV and data message. L1 frequency broadcast the C/A code
Explain each segment of the GPS:
- Space segment:
Consist of the SV’s
- control system:
Consist of the monitoring stations, master stations and backup station, These serve to monitor the position of the SV and insure that the calculated positions = the actual positions. I.E, monitor the error. If an error is present, the control segment will signal the error to the SVs to be rectified.
- User segment
name the GPS errors(9):
- Ephemeris
- SV clock error
- Ionospheric delay error
- Tropospheric propagation error
- Receiver noise error
- Multipath reception
- Dilution of precision
- Effect of aircraft maneuver
- Selective Availability
Range of GPS is known as pseudo range when -
The method used to correct the receiver time error -
it’s not corrected for receiver time error
By using a 4th satellite
Differential GPS (DGPS)
If the SV information degrades, the GPS receiver has no means of determining the degradation.
Consequentially the safety of flight may be seriously endangered. DGPS is a means of improving
the accuracy of GPS by monitoring the integrity of the SV data and warning the user of any
errors which occur. DGPS systems will provide warning of failure in the SV data and prevent or
minimize the effect of such errors, or provide failure warning and improve the accuracy of the
deduced position. There are three kinds of DGPS currently in use or under development(3):
SBAS
ABAS
GBAS
RAIM requires how many SV and why?
The fifth SV is used to determine the error of 4 SVs, but if the 5th SV is required to replace the 4th SV, RAIM is lost. Hench as 6th SV is required to continue RAIM.
SBAS consist of(segments):
Space segment
Ground segment
User segment
The NAVSTAR/GPS satellites (sv’s) required for position fixes:
2D =
3D =
RAIM =
RAIM with fault detection and exclusion =
The NAVSTAR/GPS satellites (sv’s) required for position fixes:
2D = 3 sv’s
3D = 4 sv’s
RAIM = 5 sv’s
RAIM with fault detection and exclusion = 6 sv’s
What is the deviation per dot on the HSI when using an 2-dot RNAV system in the approach mode? (student feedback required: see explanation)
A
0.5°
B
10°
C
0.5 NM
D
10 NM
A
0.5°
