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The time transmitted by a navstar gps satellite is ? [ Answer reports ]

Question 198-1 : Gps utc gmt lt

Ecqb04 november 2017 exemple 298 Gps.Gps.

The acronym given to an aircraft based augmentation system abas whereby a ?

Question 198-2 : Raim receiver autonomous integrity monitoring aaim aircraft autonomous integrity monitoring laas local airborne augmentation system capu central air processor unit

Ecqb04 november 2017 ..raim receiver autonomous integrity monitoring is technique whereby a receiver processor determines the integrity of the navigation signals raim is achieved by consistency check among pseudo range measurements it requires 5 satellites and a 6th is for isolating a faulty satellite from the navigation solution .if gps receiver uses barometric altitude as an augmentation to raim the number of satellites needed for the receiver to perform the raim function may be reduced by one exemple 302 Raim (receiver autonomous integrity monitoring).Raim (receiver autonomous integrity monitoring).

In general a gnss receiver is able to determine ?

Question 198-3 : A three dimensional position groundspeed and a precise time reference only a three dimensional position and groundspeed only a three dimensional position only a three dimensional position and a time reference

Gnss global navigation satellite systems are navigational systems that employ the use of many satellites orbiting the earth 24 is a technical minimum each satellite transmits a constant coded electromagnetic message called the prn pseudo random noise as well as a navigation message which contains extra data useful to our receiver the prn code contains immensely precise timing data from when it was transmitted by the satellite this timing data allows us to measure the time between when a message was sent and when it arrives at the receiver as we know that these electromagnetic messages travel at the speed of light we can calculate how far they have travelled between the transmitter and the receiver this distance means that we can draw a 3d sphere around the satellite called a range sphere in the knowledge that the receiver is somewhere on that sphere edge with multiple satellites in the sky above our receiver this process can happen multiple times every time giving us anther range sphere that narrows down a receiver's location further for a 3 dimensional position fix to be made we need 4 range spheres and therefore 4 usable satellites in view this is the basic principle of operation of all gnss systems . . this timing data does also mean that our receiver always has the exact time reference not only this but more modern gnss receivers can also pick up very slight changes in signal frequency that occur due to the doppler effect the doppler effect is where waves electromagnetic in this case have a slightly higher detected frequency when the transmitter and receiver are coming together but a lower frequency when moving apart as we know the exact frequency that the signal should be l1 is 1575 42 mhz and any expected movement of the satellites our receiver can calculate its own ground speed using the combined doppler effect of all the satellites in view exemple 306 A three dimensional position, groundspeed and a precise time reference.A three dimensional position, groundspeed and a precise time reference.

By using egnos in combination with gps ?

Question 198-4 : The integrity is improved by reducing the mean failure reporting time from up to 3 hours to 6 seconds no improvements are obtained apart from the redundancy a better position accuracy is obtained but the integrity of the system is not improved the errors caused by multi path and noise are eliminated

Learning objective 062 06 02 02 09 explain that integrity and safety are improved by alerting sbas users within 6 seconds if a gps malfunction occurs ..satellite based augmentation systems sbas .sbas uses the idea of differential gps dgps and does a very similar job to gbas just over a much wider area .their geosynchronous orbits mean that they stay over the same place on the earth all the time and can reduce gnss errors and increase integrity over a very large area .this means that there are multiple around the world waas for the usa egnos for europe gagan for india msas for japan etc .accuracy is enhanced through the transmission of wide area corrections for gnss range errors such as ephemeris satellite clock errors and ionospheric propagation .integrity is enhanced by the sbas network quickly detecting satellite signal errors and sending alerts to receivers that they should not track the failed satellite .this means that sbas can reduce the notice time of a failure from a potential 3 hours standard gps to only 6 seconds sbas .signal availability can also be improved as the sbas transmits ranging signals from its satellites on top of its other roles it acts as an extra gnss satellite .sbas systems include reference stations which are geographically distributed throughout the sbas service area receive gnss signals and forward them to the master station .since the locations of the reference stations are accurately known the master station can accurately calculate gnss range corrections over a very wide area ..sbas can be used to make aircraft gnss systems far more accurate on approaches 1 2 m horizontally and 3 5 m vertically to allow for lower minimums on instrument approaches using this system .they are able to give vertical guidance on approaches also similar to the role of baro vnav on lnav/vnav approaches .they can even be used to refine the gnss signal for lpv approaches localiser performance with vertical guidance which have decision heights as low as 200ft exemple 310 The integrity is improved by reducing the mean failure reporting time from up to 3 hours to 6 seconds.The integrity is improved by reducing the mean failure reporting time from up to 3 hours to 6 seconds.

Assume that one of the satellites used by a gps receiver is faulty when the ?

Question 198-5 : Is able to detect that one of the satellites is faulty but is unable to identify the faulty one is not active as the software needs at least 8 satellites to function correctly is unable to detect and identify the faulty satellite is able to detect that one of the satellites is faulty and is able to identify the faulty one

Receiver autonomous integrity monitoring raim .raim is a technique which uses extra gnss satellites to improve the integrity of gnss location data instead of the 4 satellite ranges required for a 3d gnss fix using 5 satellites can mean that the onboard raim system can continuously measure different sets of 4 signals making sure that every fix is consistent with the others each fix excludes 1 satellite so the receiver knows if they are all correct or not thereby noticing if any one satellite becomes faulty as all the seperate fixes will then be different from each other this can tell us within a few seconds if a satellite that we are using becomes faulty rather than waiting a potential 3 hours for it to be noticed and taken offline this raim feature is called fault detection fd it does not tell us which is the faulty satellite as this is mathematically impossible to work out with so little data..if we use a second extra satellite a total of 6 for a 3d fix then we can also reliably calculate which is the faulty satellite and remove it from usage called fault detection and exclusion fde ..the amount of required satellites can be reduced by 1 for 2d fixes but these are not used unless barometric altitude is fed to the gnss system which can allow an extra 'range sphere' and effectively acts like another satellite this is an air based augmentation system and occurs in a different place in the learning objectives exemple 314 Is able to detect that one of the satellites is faulty but is unable to identify the faulty one.Is able to detect that one of the satellites is faulty but is unable to identify the faulty one.

Aaim aircraft autonomous integrity monitoring is a type of airborne based ?

Question 198-6 : Relies on gnss information as well as information from additional on board sensors relies on information from additional on board sensors only relies on gnss information only can only function within the range of a ground based augmentation system

Aircraft autonomous integrity monitoring aaim .aaim is a method of monitoring the integrity of the gnss position data using information from on board sensors such as barometric altitude data irs position data and conventional nav aid autotuning vor dme position data this can allow our aircraft to notice any suspicious gnss position data and notify the pilots that it may not be correct it is a type of abas aircraft based augmentation system exemple 318 Relies on gnss information as well as information from additional on-board sensors.Relies on gnss information as well as information from additional on-board sensors.

Which statement from the choice below characterises a satellite based ?

Question 198-7 : Sbas is able to provide approach and landing operations with vertical guidance sbas is an augmentation device for ground based augmentation systems the sbas monitor stations send corrected positions to the users within the range of the station the ground reference station transmits corrections directly to the user by vhf/uhf data link

Satellite based augmentation systems sbas .sbas uses the idea of differential gps dgps and spreads it over a much wider area than gbas can do their geosynchronous orbits mean that they stay over the same place on the earth all the time and can reduce gnss errors and increase integrity over a very large area this means that there are multiple around the world waas for the usa egnos for europe gagan for india msas for japan etc .accuracy is enhanced through the transmission of wide area corrections for gnss range errors such as ephemeris satellite clock errors and ionospheric propagation .sbas systems include reference stations which are geographically distributed throughout the sbas service area receive gnss signals and forward them to the master station since the locations of the reference stations are accurately known the master station can accurately calculate gnss corrections over a wide area .sbas can be used to make aircraft gnss systems far more accurate on approaches to allow for lower minimums on instrument approaches using this system they are able to give vertical guidance on approaches also similar to the role of baro vnav on lnav/vnav approaches they can even be used to refine the gnss signal for lpv approaches localiser performance with vertical guidance which have decision heights as low as 200ft .to tune into a gnss approach with sbas augmentation a 5 digit channel is entered into the guidance system which then accesses the correct information to augment the gnss signal as required this 5 digit code will be given on any relevant approach plate along with the sbas that is to be used such as egnos for europe exemple 322 Sbas is able to provide approach and landing operations with vertical guidance.Sbas is able to provide approach and landing operations with vertical guidance.

The fully operational galileo global navigation satellite system gnss will ?

Question 198-8 : 1 30 satellites 2 3 orbital planes 3 23222 km 1 30 satellites 2 4 orbital planes 3 19100 km 1 24 satellites 2 4 orbital planes 3 20200 km 1 24 satellites 2 6 orbital planes 3 12539 km

Refer to figure .galileo is the gnss system set up by europe and a good way to remember it is that there are 3 sets of 3s 30 satellites 3 orbital planes at an orbital altitude of 23222km this number can be quoted slightly different in some publications but is always close exemple 326 1. 30 satellites 2. 3 orbital planes 3. 23222 km1. 30 satellites 2. 3 orbital planes 3. 23222 km

Which statement about satellite based augmentation systems sbas is correct ?

Question 198-9 : The use of sbas improves both the accuracy and the integrity of the position of the user the use of sbas improves neither the integrity nor the accuracy of the position of the user but augments the number of satellites available the use of sbas improves the accuracy of the position of the user but does not improve the integrity the use of sbas improves the integrity of the position of the user but does not improve the accuracy

Satellite based augmentation systems sbas .sbas uses the idea of differential gps dgps and spreads it over a much wider area than gbas can do their geosynchronous orbits mean that they stay over the same place on the earth all the time and can reduce gnss errors and increase integrity over a very large area this means that there are multiple around the world waas for the usa egnos for europe gagan for india msas for japan etc .accuracy is enhanced through detection of errors and the transmission of wide area corrections for gnss range errors such as ephemeris satellite clock errors and ionospheric propagation .integrity is enhanced by the sbas network quickly detecting satellite signal errors and sending alerts to receivers that they should not track the failed satellite an integrity warning is sent after just 6 seconds when using sbas but is up to 3 hours when using standard gnss only .signal availability can also be improved as the sbas transmits ranging signals from its satellites on top of its other roles it acts as an extra gnss satellite .sbas systems include reference stations which are geographically distributed throughout the sbas service area receive gnss signals and forward them to the master station since the locations of the reference stations are accurately known the master station can accurately calculate wide area corrections exemple 330 The use of sbas improves both the accuracy and the integrity of the position of the user.The use of sbas improves both the accuracy and the integrity of the position of the user.

How is the final approach segment fas of a gbas precision approach procedure ?

Question 198-10 : The gbas ground facility transmits the approach path guidance parameters to the gbas equipped aircraft the gnss space segment transmits the approach path guidance parameters to the gbas equipped aircraft the gbas reference receivers transmit error correction messages to the ground based azimuth and elevation guidance transmitters the gbas ground facility transmits an error correction message to the ground based azimuth and glidepath guidance transmitters

The message transmitted form the gbas ground facility to the aircraft contains one or more data sets that contain final approach segment fas data .each data set is transmitted with the associated vertical/lateral alert limits .. . fas ma vertical alert limit fasval . . . fas ma lateral alert limit faslal . ..each final approach segment fas data block contains the parameters that define a single precision approach .it is self contained and includes a means to preserve integrity from the time it is generated and validated to the time that it is used in airborne equipment .all of the information necessary to describe the paths and its designation is contained within it .this primarily includes the following .. . airport identification . . . runway designation and position . . . procedure type provides flexibility for advanced procedures such as departure or curved approach . . . procedure name . . . runway surveyed points defining the fas path . ..the fas path is a line in space defined by the following parameters .. . landing threshold point or fictitious threshold point ltp/ftp . . . flight path alignment point fpap . . . ltp/ftp height . . . threshold crossing height tch . . . glide path angle gpa exemple 334 The gbas ground facility transmits the approach-path guidance parameters to the gbas-equipped aircraft.The gbas ground facility transmits the approach-path guidance parameters to the gbas-equipped aircraft.

The navigation message of a gps satellite contains the parameters of the model ?

Question 198-11 : The receiver to calculate the delay of gps signals passing through the ionosphere the use of the satellites with the least tropospheric delay the receiver to choose the satellites with the best geometric dilution of precision the authorised users to work on the l1 and l2 frequencies

Not only do gnss satellites transmit prn pseudo random noise timing and identification data they also transmit a whole array of navigational data to the receiver called the nav message .the nav message is sent in 25 frames of 30 seconds each so takes 12 5 minutes in total to download to the receiver .the information included in the nav message is .. almanac non precise data about where the satellites should be at any one time this does not need to be updated very often . ephemeris precise data about the exact locations of each satellite held in each satellite separately . satellite clock correction correction data for any errors within the satellite clocks . utc correction time difference between utc and the gps time . ionospheric model a mathematic model of the ionosphere based on an 11 year solar cycle which allows the receiver to calculate out any large errors that occur due to the prn signals slowing down through the ionosphere this is not a perfect system as the ionosphere is not 100% predictable but is far better than no correction . satellite health status either healthy usable or unhealthy unusable exemple 338 The receiver to calculate the delay of gps signals passing through the ionosphere.The receiver to calculate the delay of gps signals passing through the ionosphere.

What is the minimum number of satellites required by a gps in order to obtain a ?

Question 198-12 : 4 6 3 5

Satellite navigation is based on a global network of satellites that transmit radio signals in medium earth orbit the basic gps service provides users with approximately 7 8 meter accuracy 95% of the time anywhere on or near the surface of the earth to accomplish this each satellite emits signals to receivers that determine their location by computing the difference between the time that a signal is sent and the time it is received travelling at 300 000 km/sec the receiver uses the time difference between the time of signal reception and the broadcast time to compute the distance or range from the receiver to the satellite with information about the ranges to 3 satellites and the location of the satellite when the signal was sent the receiver can compute its own three dimensional position pay attention the clock on the gps receiver might not be as accurate as the atomic clock on the gps satellite creating a very slight accuracy problem clock error gps satellites broadcast two codes the coarse/acquisition c/a code which is unique to the satellite and the navigation data message the codes contain information the receiver needs to determine latitude longitude and altitude and to synchronise its quartz clock with gps time used through the gps system current approvals for the use of gps equipment in ifr operations require gps derived data to be in the wgs 84 coordinate system or worldwide geodetic datum standard 84 .summary .using range from 3 satellites accurate 2d position fix is obtained lat long time .using range from 4 satellites accurate 3d position fix is obtained lat long altitude time exemple 342 44

Which of the following satellite navigation systems has full operational ?

Question 198-13 : Navstar/gps nnss transit glonass cospas sarsat

Learning objective 062 06 01 01 01 state that there are four main gnsss these are usa navigation system with timing and ranging global positioning system navstar gps russian global navigation satellite system glonass european galileo under construction chinese beidou under construction .we have to go with whatever the learning objective says on this and as the most recent lo states that only navstar/gps and glonass are functional any other options are not correct .glonass is not certified for use in europe for many reasons the trust in the system is very low and it does not use the wgs 84 database so is not easily compatible with other gnss systems such as navstar/gps which is proven and well certified exemple 346 Navstar/gpsNavstar/gps

Errors in gps satellite orbits are due to ?

Question 198-14 : The solar wind and the gravitation of the sun moon and planets solar and lunar precession earth and lunar precession the lunar wind and the gravitation of the earth moon and stars

Learning objective 062 06 01 03 07 state that errors in the satellite orbits are due to solar winds gravitation of the sun and the moon .these are the effects which can cause changes in the orbits of gnss satellites or any satellite .the gravitational ones can be modelled to know when they might occur but solar winds are much more difficult to forecast .realistically as long as a satellite is accurately tracked to update its orbit these effects are usually quite miniscule and none consequential .note it is unknown whether the current question on easa 2020 syllabus contains the planets as having a gravitational effect as this was removed from the learning objectives in the transition to new syllabus exemple 350 The solar wind and the gravitation of the sun, moon and planets.The solar wind and the gravitation of the sun, moon and planets.

One of the advantages of a satellite based augmentation system sbas over a ?

Question 198-15 : The coverage area of an sbas is much larger than that of a gbas an sbas does not like a gbas need ground stations for the estimation of the pseudo range corrections the rate at which the pseudo range corrections reach the users is much higher for a gbas than for an sbas the pseudo range corrections of an sbas are much more accurate than those of a gbas

Refer to figures .gbas ground based augmentation system.gbas is a system that attempts to reduce the natural errors within the gnss system by providing very localised augmentation to the satellite signals via a vhf data broadcast vdb that a suitably equipped aircraft can receive and use to fix any position errors it is also called 'differential gps' and can correct for errors induced by satellite clocks ephemeris and ionospheric propogation to make the augmented gnss signal very accurate .these are measurable errors which are measured by multiple receiver antennas and interpretted by a ground station usually located at an airport which can make use of this highly accurate gnss errors in the receiver multipath signals and some small atmospheric propogation errors can still occur but the intention is to get the accuracy below 1m for aircraft on final approach the gbas can also give integrity warnings about faulty satellites as it should be able to detect any such faults at the nearby antennas .gbas is limited in the fact that it is very short range spanning approximately 20 nm 30 km according to the old syllabus away from the relevant ground station although there is the capability for a network of such stations in the future ..sbas satellite based augmentation system.sbas uses the idea of differential gps dgps and spreads it over a much wider area than gbas can do their geosynchronous orbits mean that they stay over the same place on the earth all the time and can reduce gnss errors and increase integrity over a very large area this means that there are multiple around the world waas for the usa egnos for europe gagan for india msas for japan etc .sbas works in a very similar way to gbas but the reference antennas send their corrections to a master control station which communicates the wide area corrections to the geostationary satellites for effective distribution over their large usable area .sbas can also give integrity warnings in the same way that gbas can bringing the alerting time down from a potential 3 hours for standard gnss to 6 seconds for sbas users exemple 354 The coverage area of an sbas is much larger than that of a gbas.The coverage area of an sbas is much larger than that of a gbas.

In relation to the navstar/gps satellite navigation system what is involved in ?

Question 198-16 : Fixed ground stations compute position errors and transmit correction data to a suitable receiver on the aircraft signals from satellites are received by 2 different antennas which are located a fixed distance apart this enables a suitable receiver on the aircraft to recognise and correct for multipath errors the difference between signals transmitted on the l1 and l2 frequencies are processed by the receiver to determine an error correction receivers from various manufacturers are operated in parallel to reduce the characteristic receiver noise error

Refer to figure .differential gps dgps .dgps differential gps is a method of augmenting gnss signals to remove measurable errors such as satellite clock error ephemeris and ionospheric propogation effects this is done by placing multiple reference antennas on the ground in the region that is to be used then measuring their gnss computed position against their actual known position then calculating the corrections to be made to each satellite's pseudo range this allows accuracies of around 1 m in many cases and is the technique used by gbas ground based augmentation systems for small area aviation use cases as well as sbas satellite based augmentation systems for large area dgps uses .receiver errors multipath signals and some small atmospheric propogation errors cannot be accounted for but they do not affect the accuracy too much dgps systems like gbas and sbas can also be very useful for monitoring the integrity of gnss satellites as they are constantly monitoring the signals and can give loss of integrity alerts in 6 seconds rather than a potential 3 hours for standard gps exemple 358 Fixed ground stations compute position errors and transmit correction data to a suitable receiver on the aircraft.Fixed ground stations compute position errors and transmit correction data to a suitable receiver on the aircraft.

When a gps position is augmented by egnos what time to alert can be expected ?

Question 198-17 : 6 seconds 15 seconds 0 3 seconds 10 seconds

Satellite based augmentation systems sbas .sbas uses the idea of differential gps dgps and spreads it over a much wider area than gbas can do their geosynchronous orbits mean that they stay over the same place on the earth all the time and can reduce gnss errors and increase integrity over a very large area this means that there are multiple around the world waas for the usa egnos for europe gagan for india msas for japan etc .accuracy is enhanced through the transmission of wide area corrections for gnss range errors detected by a network of ground antennas such as ephemeris satellite clock errors and ionospheric propagation .integrity is enhanced by the sbas network quickly detecting satellite signal errors and sending alerts to receivers that they should not track the failed satellite this can bring the time of a loss of integrity alert from a potential 3 hours down to just 6 seconds this is far more acceptable for precision approaches etc .signal availability can also be improved as the sbas transmits ranging signals from its satellites on top of its other roles it acts as an extra gnss satellite exemple 362 6 seconds6 seconds

In an aircraft based augmentation system abas the method of integrity ?

Question 198-18 : Receiver autonomous integrity monitoring raim aircraft station autonomous integrity monitoring asaim aircraft autonomous integrity monitoring aaim gnss autonomous integrity monitoring gaim

The term aircraft based augmentation system abas covers both aaim aircraft autonomous integrity monitoring and raim receiver autonomous integrity monitoring aaim is a method of monitoring the integrity of the gnss position data using information from on board sensors such as barometric altitude data irs position data and potentially even conventional nav aid autotuning vor dme position data this can allow our aircraft to notice any suspicious gnss position data and notify the pilots that it may not be correct raim is a system which uses extra gnss satellites to effectively verify the working order of the usual 4 required for a 3d position fix 1 extra satellite 5 in total can give the ability to notice when a fault occurs fault detection 2 extra satellites 6 in total gives the ability to detect and identify which satellite is faulty fault detection and exclusion exemple 366 Receiver autonomous integrity monitoring (raim).Receiver autonomous integrity monitoring (raim).

Which statement correctly describes the principle of sbas operation a ?

Question 198-19 : Geostationary satellites to gnss receivers distributed over a wide area geostationary satellites to gnss receivers located in a small local area ground based transmitters to gnss receivers distributed over a wide area ground based transmitters to gnss receivers located in a small local area

Refer to figure .satellite based augmentation systems sbas .sbas uses the idea of differential gps dgps and spreads it over a much wider area than gbas can do their geosynchronous orbits mean that they stay over the same place on the earth all the time and can reduce gnss errors and increase integrity over a very large area this means that there are multiple around the world waas for the usa egnos for europe gagan for india msas for japan etc .accuracy is enhanced through the transmission of wide area corrections for gnss range errors such as ephemeris satellite clock errors and ionospheric propagation sbas systems include reference stations which are geographically distributed throughout the sbas service area which receive gnss signals and forward them to the master station since the locations of the reference stations are accurately known the master station can accurately calculate corrections to each gnss satellite's pseudo range these corrections can then be used to refine gnss measurements over huge areas via the geostationary satellites above those areas .geostationary satellites are those that orbit exactly once every day meaning that they stay over the same point on earth to do this they also have to be over the equator .sbas can be used to make aircraft gnss systems far more accurate on approaches and massively increase integrity monitoring to allow for lower minimums on instrument approaches using this system they are able to give vertical guidance on approaches also similar to the role of baro vnav on lnav/vnav approaches they can even be used to refine the gnss signal for lpv approaches localiser performance with vertical guidance which have decision heights as low as 200ft exemple 370 Geostationary satellites to gnss receivers distributed over a wide area.Geostationary satellites to gnss receivers distributed over a wide area.

Which of the following correctly describes the principle of receiver autonomous ?

Question 198-20 : Requires at least five satellites with good geometry to provide the service of detecting faulty signals and alerting the crew is guaranteed to be available for all scheduled flight operations at mid latitudes must be assured at all times in order to utilise global navigation satellite system gnss signals in any augmentation system is available if range from at least three satellites is supplemented by barometric aiding

Receiver autonomous integrity monitoring raim uses redundant signals to produce multiple gps position fixes compare them and detect the faults with redundant gps systems .raim only works with a minimum of five satellites and if sufficient geometry is visible to it raim availability is very important when using the geometry for safety ciritical applications . .availability is a function of the geometry and other environmental conditions exemple 374 Requires at least five satellites with good geometry to provide the service of detecting faulty signals and alerting the crew.Requires at least five satellites with good geometry to provide the service of detecting faulty signals and alerting the crew.

Which statement about dilution of precision is correct the value of the ?

Question 198-21 : Geometry and the number of satellites in view accuracy with which the range between the satellite and receiver can be measured availability of receiver autonomous integrity monitoring software availability of aircraft based augmentation systems

Refer to figure .dilution of precision dop .dop error may be caused by the relative positions of the satellites used to calculate a position to get a better understanding the concept of geometrical dop gdop is often used poor gdop values mean ‘bad’ positioning of satellites on the contrary ‘well’ distributed satellites produce good values satellites that are closer together will greate a less accurate position measurement due to the shallow angle difference between their pseudo range spheres whereas satellites which are well spread around the sky will give a more accurate position of the receiver as the pseudo range spheres cut each other at better angles exemple 378 Geometry and the number of satellites in view.Geometry and the number of satellites in view.

Which statement is correct about the sbas satellite based augmentation systems ?

Question 198-22 : In an sbas the pseudo range corrections are sent to the users by geostationary satellites in an sbas the pseudo range correction are sent to the users by the satellite of the satellite systems e g by gps satellites for gps in an sbas the pseudo range correction are determined by geostationary satellites and sent to the users by a network of ground stations in an sbas the pseudo range corrections are determined by geostationary satellites and sent to the users by the satellite of the satellite systems e g by gps satellites for gps

Refer to figures .satellite based augmentation systems sbas .sbas uses the idea of differential gps dgps and spreads it over a much wider area than gbas can do their geosynchronous orbits mean that they stay over the same place on the earth all the time and can reduce gnss errors and increase integrity over a very large area this means that there are multiple around the world waas for the usa egnos for europe gagan for india msas for japan etc .accuracy is enhanced through the transmission of wide area corrections for gnss range errors such as ephemeris satellite clock errors and ionospheric propagation sbas systems include reference stations which are geographically distributed throughout the sbas service area which receive gnss signals and forward them to the master station since the locations of the reference stations are accurately known the master station can accurately calculate corrections to each gnss satellite's pseudo range these corrections can then be used to refine gnss measurements over huge areas via the geostationary satellites above those areas .geostationary satellites are those that orbit exactly once every day meaning that they stay over the same point on earth to do this they also have to be over the equator .sbas can be used to make aircraft gnss systems far more accurate on approaches and massively increase integrity monitoring to allow for lower minimums on instrument approaches using this system they are able to give vertical guidance on approaches also similar to the role of baro vnav on lnav/vnav approaches they can even be used to refine the gnss signal for lpv approaches localiser performance with vertical guidance which have decision heights as low as 200ft exemple 382 In an sbas the pseudo range corrections are sent to the users by geostationary satellites.In an sbas the pseudo range corrections are sent to the users by geostationary satellites.

The system capable of on the ground measuring the signal errors transmitted by ?

Question 198-23 : Gbas tbas sbas abas

Refer to figure .this question is quite badly worded but it is asking which system allows ground receivers to measure calculate and directly transmit those errors to the local receivers .this is referring to gbas ground based augmentation system ..gbas is a system that attempts to reduce the natural errors within the gnss system by providing very localised augmentation to the satellite signals via a direct vhf data broadcast vdb that a suitably equipped aircraft can receive and use to fix any position errors .it is also called differential gps and can correct for errors induced by satellite clocks ephemeris and ionospheric propagation to make the augmented gnss signal very accurate .these are measurable errors which are measured by multiple receiver antennas and interpreted by a ground station usually located at an airport which can make use of this highly accurate gnss .errors in the receiver multipath signals and some small atmospheric propagation errors can still occur but the intention is to get the accuracy below 1m for aircraft on final approach .the gbas can also like its satellite based cousin sbas give integrity warnings about faulty satellites as it should be able to detect this at the nearby antennas ..gbas is limited in the fact that it is very short range spanning approximately 30km away from the relevant ground station although it is incredibly accurate and used for complex approaches down to ils minimums and lower minimums in the future is very much possible exemple 386 GbasGbas

Which statement about a satellite based augmentation system sbas is correct ?

Question 198-24 : Sbas is able to provide guidance for precision approaches sbas is an augmentation device for ground based augmentation systems sbas is able to provide approach and landing operations with horizontal guidance only sbas is able to provide approach and landing operations with vertical guidance only

Refer to figure it is the new approach classifications which we think the examiners may have started to use . note with recent changes to the regulations we are looking for any exam feedback to verify the question and options thank you rnp approach rnp apch rnp apch can be performed in 3 different ways to 3 different minima lnav only is a non precision approach similar to a vor approach using gnss lnav/vnav uses gnss plus a barometric vnav or sbas system to give vertical guidance on the approach and is a 3 dimensional 3d approach with lower minimums than lnav only lpv minimums are even lower as low as 200ft ils cat i due to the narrowing effect of the allowed track like a localiser and the incredibly accurate position data and integrity is gained by using sbas augmentation to the gnss signal it is also a 3d approach standard with vertical guidance sbas cat i approaches are precision approaches according to the more recent documents from icao we are currently unsure as whether the examiners have caught up with these changes so be on the lookout for the older questions which refer to lpv approaches as apv approach with vertical guidance classification into precision and non precision approaches is no longer operationally useful in the current age instead it is better to use 2d and 3d sbas satellite based augmentation system operations use an extra geostationary satellite and a wide network of ground antennas with a master station to calculate the signal errors of gnss location data then apply a correction depending on the user's location to reduce measurable gnss errors to a very small error margin they also increase integrity monitoring so an alert of any unsuitability is issued within 6 seconds commonly confused is the gbas landing system gls which is actually not a form of rnp apch and is a separate type of precision approach that just happens to use ground based augmentation on gnss signals a localised version of sbas exemple 390 Sbas is able to provide guidance for precision approaches.Sbas is able to provide guidance for precision approaches.

How does the gbas precision approach work ?

Question 198-25 : A gbas ground station sends correction data to the aircraft which uses the data to determine the correct azimuth and glidepath a gbas ground station sends correction signals to a ground transmitter which sends azimuth and glidepath information to the aircraft a gbas satellite sends azimuth and glidepath information to the aircraft a gbas station sends approach path information directly to the aircraft

Refer to figure . .gbas ground based augmentation system . .gbas is a system that attempts to reduce the natural errors within the gnss system by providing very localised augmentation to the satellite signals via a vhf data broadcast vdb that a suitably equipped aircraft can receive and use to fix any position errors .it is also called differential gps and can correct for errors induced by satellite clocks ephemeris and ionospheric propagation to make the augmented gnss signal very accurate .these are measurable errors which are measured by multiple receiver antennas then interpreted and distributed by a ground station via a vdb antenna usually located at an airport which can make use of this highly accurate gnss .there are still some errors that cannot be accounted for but these are small .gbas also provides integrity information about the gnss satellites .the operation of gbas allows it to work in the same way as an ils approach down to 200ft minimums currently and this is called the gbas landing system or gls and is a precision approach .it is tuned using a 5 digit channel number that picks up the correct vhf datalink signals for that approach .the vhf datalink called the vdb sends a signal that corrects the gnss position so that the onboard navigation system can guide the aircraft accurately on the approach in both azimuth and glidepath ..note for this question the examiner is mostly asking what signals are sent in the vhf data broadcast .the correct answer is correction data as this is exactly what the gbas system does it corrects the gnss position .the gbas system does not send glidepath and azimuth data to the aircraft like an ils or mls would this is the primary objective of this question .the gbas ground station does not tell the aircraft that it is 2 m right and 4 ft above the correct position it tells it to adjust its gnss position by a certain amount then the aircraft makes sure it follows the approach correctly .it also does not matter whether the vdb antenna is classed as part of the ground station or not that is not the defining difference in this question .the ground station transmits vdb signals via the antenna to the aircraft which still means that the ground station sends signals to the aircraft exemple 394 A gbas ground station sends correction data to the aircraft, which uses the data to determine the correct azimuth and glidepath.A gbas ground station sends correction data to the aircraft, which uses the data to determine the correct azimuth and glidepath.

What does abas stand for ?

Question 198-26 : Aircraft based augmentation systems aircraft based application safety aerial broadcast application systems aircraft based augmentation safety

Abas aircraft based augmentation system.gbas ground based augmentation system .sbas satellite based augmentation system .aircraft based augmentation system abas .the aircraft based augmentation can provide gnss information as necessary for supplemental means of navigation .an abas is basically a system that augments and/or integrates the information obtained from the other gnss elements with information available on board the aircraft exemple 398 Aircraft-based augmentation systems.Aircraft-based augmentation systems.

Maximum coverage of a ground based augmentation system gbas station is… ?

Question 198-27 : 20 nm 10 nm 12 nm 30 nm

Radio navigation 062 learning objectives state that for a gbas station the coverage is about 20 nm ground based augmentation system gbas provides its service to a local area approximately a 30 km radius .the signal coverage is designed to support the aircraft's transition from en route airspace into and throughout the terminal area airspace note please take care to notice the units .note 2 the old syllabus stated 'state that for a gbas station the coverage is about 30 km ' exemple 402 20 nm20 nm

How is the gps receiver able to calculate aircraft's ground speed ?

Question 198-28 : Using the space vehicle sv doppler frequency shift using the time measured from the signal leaving the satellite to the receiver using the pseudo range measurements using aircraft position and known reference points on the ground

Doppler shift.the doppler principle can be used to determine the relative speed between moving objects by measuring the difference between transmitted and received frequencies using the space vehicle sv doppler frequency shift and/or change in receiver position over time whenever a relative motion exists between the transmitter and the receiver of a radio wave a change in frequency occurs the magnitude of this change is proportional to the relative motion exemple 406 Using the space vehicle (sv) doppler frequency shift.Using the space vehicle (sv) doppler frequency shift.

For a satellite to be visible to a gps receiver ?

Question 198-29 : It needs a higher elevation than 5° above the horizon it needs a higher elevation than 5° below the horizon it needs a higher elevation than 15° above the horizon it needs a higher elevation than 55° above the horizon

Global navigation satellite systems gnss .. a satellite will typically be masked from the group of satellites used for position determination until it rised at least 5º above the horizon ..elevation mask refers to an elevation relative to the horizon in which gps/gnss satellites contained within are not used in a positional solution there is a significant increase in distance between a receiver and a satellite on the edge of the horizon as opposed to a satellite directly above the receiver this increase in distance allows for more ionospheric error resulting in poor accuracy when used in the positional solution exemple 410 It needs a higher elevation than 5° above the horizon.It needs a higher elevation than 5° above the horizon.

Geometric dilution of precision gdop error can be minimized when… ?

Question 198-30 : One satellite is directly overhead and 3 others are close to the horizon 120 degrees apart three satellites are spaced by 120 degrees in the vertical plane and one satellite is directly overhead two satellites are spaced by 180 degrees in azimuth one satellite is directly overhead and one satellite is directly opposed to the satellite overhead four satellites are spaced by 90 degrees in azimuth

Refer to figures . .gdop geometric dilution of precision describes the error caused by the relative position of the gps satellites basically the more signals a gps receiver can see spread apart versus close together the more precise it can be .. the geometry that will provide the most accurate fixing information is one satellite directly overhead the receiver and the other three close to the horizon and spaced 120 degrees apart in azimuth exemple 414 One satellite is directly overhead and 3 others are close to the horizon 120 degrees apart.One satellite is directly overhead and 3 others are close to the horizon 120 degrees apart.

Referring to the navstar/gps satellite navigation system what is the meaning of ?

Question 198-31 : It is a technique that ensures the integrity of the provided data by redundant measurements it is a technique whereby the receivers of the world wide distributed monitor stations – ground segment – automatically determine the integrity of the navigation message it is a method whereby a receiver ensures the integrity of the pseudo random noise prn code transmitted by the satellites it is the ability of the gps satellites to check the integrity of the data transmitted by the monitoring stations of the ground segment

062 06 01 02 21 los define ‘receiver autonomous integrity monitoring raim ’ as a technique that ensures the integrity of the provided data by redundant measurements .receiver autonomous integrity monitoring raim is a technology developed to assess the integrity of global positioning system gps signals in a gps receiver system raim is a technique by which a receiver checks the reliability of the signals it is receiving and can detect if one of the signals is incorrect it monitors more than 4 satellites in view and excludes the one providing an inaccurate signal when necessary with this technique raim can maintain an accurate 3d fix by monitoring 5 satellites even if satellite signals become temporarily erroneous it improves redundancy based on multiple satellite signals and no external systems – the benefit is that a faulty satellite may be excluded and the raim function can still be further maintained exemple 418 It is a technique that ensures the integrity of the provided data by redundant measurements.It is a technique that ensures the integrity of the provided data by redundant measurements.

You are flying at high latitude and you are unable to identify your position ?

Question 198-32 : Irs and barometric altimeter barometric altimeter and clock only on board clock to aid time reference and sbas ins and clock

Aaim uses additional on board sensors to cross check the gnss position the aaim compares the 3d position with navigation information from on board systems and not with signals from other satellites the navigation systems on board may be self contained inertial reference system irs or radio signals from navigation aids furthermore redundancy to satellite signals may be offered by the barometric altimeter as a back up for positioning in the vertical dimension .note this question has been created based on incomplete feedback we would kindly ask that you report it to us if you have any further info on this question exemple 422 Irs and barometric altimeter.Irs and barometric altimeter.

What is the name of a main chinese gnss system ?

Question 198-33 : Beidou gagan egnos wass

There are four main gnsss these are .. usa navigation system with timing and ranging global positioning system navstar gps . russian global navigation satellite system glonass . european galileo under construction . chinese beidou under construction exemple 426 BeidouBeidou

Which of the follwing codes can an unauthorized aircraft read ?

Question 198-34 : C/a codes neither c/a nor p codes p and c/a codes p codes

Satellites transmit navigation data and ranging signals on two main l band frequencies l1 at 1 575 mhz and l2 at 1 227 mhz .l1 frequency provided the standard positioning service sps for civilian users and l2 frequency was used by authorised users such as the military in addition to l1 to achieve precision positioning service pps .. l1 at 1575 mhz provides sps and is used by civilian and military users .transmits c/a and p codes . l2 at 1227 mhz provides pps and is used by authorized users military .transmits p codes exemple 430 C/a codesC/a codes

Which system is capable of measuring on the ground the signal errors ?

Question 198-35 : Sbas abas rbas gbas

Satellite based augmentation systems sbas .sbas operates on the principle of sending navigation correction information to satellites based on actual measurements of signal errors on the ground the signals transmitted by the gnss satellite constellation are transferred to a central computing centre and monitored by ground station and integrity is assessed differential corrections are then transmitted as part of integrity messages within the navigation messages exemple 434 SbasSbas

What does the term 'sbas' stand for ?

Question 198-36 : Satellite based augmentation system supplement based augmentation system service broadcast application system satellite based area system

Satellite based augmentation systems sbas .sbas operates on the principle of sending navigation correction information to satellites based on actual measurements of signal errors on the ground the signals transmitted by the gnss satellite constellation are transferred to a central computing centre and monitored by ground station and integrity is assessed differential corrections are then transmitted as part of integrity messages within the navigation messages exemple 438 Satellite based augmentation systemSatellite based augmentation system

What is the minimum ground based augmentation system gbas plan coverage ?

Question 198-37 : 15 nm from the landing threshold within 35° apart the final approach path and 10° apart between 15 and 20 nm 25 nm from the landing threshold within 45° apart the final approach path and 20° apart between 25 and 20 nm 25 nm from the landing threshold within 35° apart the final approach path and 10° apart between 25 and 30 nm 15 nm from the landing threshold within 45° apart the final approach path and 20° apart between 15 and 20 nm

Refer to figure .ground base augmentation systems gbas the basic principle of gbas is to measure the errors of the gnss satellite signals and to relay these errors to the user receivers the average gbas coverage must be adequate to provide precise augmentation to an aerodrome terminal area the approximate coverage of the dgps antenna is 30 40 km gbas corrects the gps signal to approx + 4 m vertically and + 16 m horizontally gbas coverage from the leading threshold to enable precise approach navigation is + 35º along the centreline within 15 nm + 10º between 15 nm and 20 nm exemple 442 15 nm from the landing threshold within 35° apart the final approach path and 10° apart between 15 and 20 nm.15 nm from the landing threshold within 35° apart the final approach path and 10° apart between 15 and 20 nm.

In the global navigation satellite system gnss what is the user equivalent ?

Question 198-38 : Residual errors in the receivers which have not been corrected the correction for the receiver errors as transmitted in the navigation message inaccuracies from the geometry of the satellites above the user's horizon the correction for the receiver clock error as transmitted by a differential station

The user equivalent range error uere is the maximum position error that has to be expected by the user and can be calculated as the square root of the sum of all individual errors squared ionospheric propagation delay satellite clock error satellite orbital variations multipath propagation uere is therefore the value of all residual errors affecting the receiver position after attempts have been made to compensate the actual position error to be expected is however not only affected by uere another factor is the geometric dilution of position gdop . the total position error can be computed by multiplying uere by gdop exemple 446 Residual errors in the receivers which have not been corrected.Residual errors in the receivers which have not been corrected.

In the navstar gps system what can authorised users calculate positions from ?

Question 198-39 : Pps as well as the less accurate sps c/a code as well as the less accurate sbas sps as well as the less accurate pps sbas as well as the less accurate c/a code

There are two modes of operation of navstar gps each with a different accuracy the standard positioning service sps is available for civilian users the precise position service pps is only available for authorised users such as the military pps provides a higher accuracy than sps l1 at 1575 mhz provides sps and is used by civilian and military users transmits both c/a and p codes . l2 at 1227 mhz provides pps and is used by authorized users military transmits p codes exemple 450 Pps as well as the less accurate sps.Pps as well as the less accurate sps.

An estimate of the position accuracy from the global navigation satellite ?

Question 198-40 : Geometric dilution of precision gdop and user equivalent range error uere the correction for the receiver clock error as transmitted by a differential station inaccuracies from the geometry of the satellites above the user's horizon user equivalent range error uere alone

The user equivalent range error uere is the maximum position error that has to be expected by the user and can be calculated as the square root of the sum of all individual errors squared ionospheric propagation delay satellite clock error satellite orbital variations multipath propagation uere is therefore the value of all residual errors affecting the receiver position after attempts have been made to compensate the actual position error to be expected is however not only affected by uere another factor is the geometric dilution of position gdop . the total position error can be computed by multiplying uere by gdop exemple 454 Geometric dilution of precision (gdop) and user equivalent range error (uere).Geometric dilution of precision (gdop) and user equivalent range error (uere).

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