18 Global Navigation Satellite Systems (GNSS)

Combined GPS and GLONASS Systems

Receiver systems combining GPS and GLONASS are under development. The ability to combine positional information from the two systems will provide improved accuracy and enhanced integrity monitoring. However, since the SV systems use different models of the earth, the GLONASS PZ90 generated information will need to be converted to the GPS WGS84 model, or vice versa, to provide the final position.

(GNSS) Systems Satellite Navigation Global 18

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Questions 18

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1.NAVSTAR/GPS operates in the ....... band the receiver determines position by .......:

a.	UHF	range position lines
b.	UHF	secondary radar principles
c.	SHF	secondary radar principles
d.	SHF	range position lines

2.The NAVSTAR/ GPS control segment comprises:

a.the space segment, the user segment and the ground segment

b.a ground segment and the INMARSAT geostationary satellites

c.a master control station, a back-up control station and five monitoring stations

d.a master control station, a back-up control station, five monitoring stations and the INMARSAT geostationary satellites

3.The orbital height and inclination of the NAVSTAR/GPS constellation are:

a.20 180 km, 65°

b.20 180 km, 55°

c.19 099 km, 65°

d.19 099 km, 55°

4.The model of the earth used for NAVSTAR/GPS is:

a.WGS90

b.PZ90

c.WGS84

d.PZ84

5.The minimum number of satellites required for a 3D fix is:

a.3

b.4

c.5

d.6

6.The NAVSTAR/GPS operational constellation comprises how many satellites?

a.12

b.21

c.24

d.30

7.The most accurate fixing information will be obtained from:

a.four satellites spaced 90° apart at 30° above the visual horizon

b.one satellite close to the horizon and 3 equally at 60° above the horizon

c.one satellite directly overhead and 3 equally spaced at 60° above the horizon

d.one satellite directly overhead and 3 spaced 120° apart close to the horizon

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18 Questions

8.	The most significant error of GNSS is:
	a.	PDOP
	b.	receiver clock
	c.	ionospheric propagation
	d.	ephemeris

9.	The frequency available to non-authorized users of NAVSTAR/GPS is:
	a.	1227.6 MHz
	b.	1575.42 MHz
	c.	1602 MHz
	d.	1246 MHz

10.	The purpose of the pseudo-random noise codes in NAVSTAR/GPS is to:
	a.	identify the satellites
	b.	pass the almanac data
	c.	pass the navigation and system data
	d.	pass the ephemeris and time information

	11.	The	minimum number of satellites required for receiver autonomous integrity
		monitoring is:
		a.	3
		b.	4
		c.	5
		d.	6
	12.	If a receiver has to download the almanac, the time to do this will be:
		a.	2.5 minutes
18		b.	12.5 minutes
		c.	25 minutes
Questions		d.	15 minutes
	13.	The use of LAAS and WAAS remove the errors caused by:
		a.	propagation, selective availability, satellite ephemeris and clock
		b.	selective availability, satellite ephemeris and clock
		c.	PDOP, selective availability and propagation
		d.	receiver clock, PDOP, satellite ephemeris and clock
	14.	The most accurate satellite fixing information will be obtained from:
		a.	NAVSTAR/GPS & GLONASS
		b.	TRANSIT & NAVSTAR/GPS
		c.	COSPAS/SARSAT & GLONASS
		d.	NAVSTAR/GPS & COSPAS/SARSAT

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	15.	A LAAS requires:
		a.	an accurately surveyed site on the aerodrome and a link through the INMARSAT
			geostationary satellites to pass corrections to X, Y & Z coordinates to aircraft
		b.	an accurately surveyed site on the aerodrome and a link through the INMARSAT
			geostationary satellites to pass satellite range corrections to aircraft
		c.	an accurately surveyed site on the aerodrome and a system known as a
			pseudolite to pass satellite range corrections to aircraft
		d.	an accurately surveyed site on the aerodrome and system known as a pseudolite
			to pass corrections to X, Y & Z coordinates to aircraft
	16.	The position derived from NAVSTAR/GPS satellites may be subject to the following
		errors:
		a.	selective availability, sky wave interference, PDOP
		b.	propagation, selective availability, ephemeris
		c.	PDOP, static interference, instrument
		d.	ephemeris, PDOP, siting
	17.	EGNOS is:
		a.	the proposed European satellite navigation system
		b.	a LAAS
		c.	a WAAS
		d.	a system to remove errors caused by the difference between the model of the
			earth and the actual shape of the earth
	18.	The PRN codes are used to:
		a.	determine the time interval between the satellite transmission and receipt of
			the signal at the receiver
		b.	pass ephemeris and clock data to the receivers
		c.	synchronize the receiver clocks with the satellites clocks	18
		d.	determine the range of the satellites from the receiver
					Questions
	19.	The availability of two frequencies in GNSS:
		a.	removes SV ephemeris and clock errors
		b.	reduces propagation errors
		c.	reduces errors caused by PDOP
		d.	removes receiver clock errors
	20.	The NAVSTAR/GPS reference system is:
		a.	A geo-centred 3D Cartesian coordinate system fixed with reference to the sun
		b.	A geo-centred 3D Cartesian coordinate system fixed with reference to the
			prime meridian, equator and pole
		c.	A geo-centred 3D Cartesian coordinate system fixed with reference to space
		d.	A geo-centred 3D system based on latitude, longitude and altitude

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18 Questions

	21.	The initial range calculation at the receiver is known as a pseudo-range, because it
		is not yet corrected for:
		a.	receiver clock errors
		b.	receiver and satellite clock errors
		c.	receiver and satellite clock errors and propagation errors
		d.	receiver and satellite clock errors and ephemeris errors
	22.	The navigation and system data message is transmitted through the:
		a.	50 Hz modulation
		b.	the C/A and P PRN codes
		c.	the C/A code
		d.	the P code
	23.	An all in view receiver:
		a.	informs the operator that all the satellites required for fixing and RAIM are in
			available
		b.	checks all the satellites in view and selects the 4 with the best geometry for
			fixing
		c.	requires 5 satellites to produce a 4D fix
		d.	uses all the satellites in view for fixing
	24.	When using GNSS to carry out a non-precision approach the MDA will be determined
		using:
		a.	barometric altitude
		b.	GPS altitude
		c.	radio altimeter height
		d.	either barometric or radio altimeter altitude
	25.	If an aircraft manoeuvre puts a satellite being used for fixing into the wing shadow
	18	then:
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		a.	the accuracy will be unaffected
		b.	the accuracy will be temporarily downgraded
		c.	the receiver will automatically select another satellite with no degradation in
			positional accuracy
		d.	the receiver will maintain lock using signals reflected from other parts of the
			aircraft with a small degrading of positional accuracy
	26.	Which of the following statements concerning NAVSTAR/GPS time is correct?
		a.	Satellite time is the same as UTC
		b.	The satellite runs its own time based on seconds and weeks which is
			independent of UTC
		c.	The satellite runs its own time based on seconds and weeks which is correlated
			with UTC
		d.	Satellite time is based on sidereal time

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Questions 18

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