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What is the primary use of the radar fitted onboard a modern civilian transport ? [ Answer reports ]

Question 195-1 : Detecting areas of wet convective weather transmitting data to atc for surveillance purposes detecting other aircraft providing the main input to an anti collision system

Radar has many uses in the world in aviation primary radar can be used to spot aircraft and weather but in the air aircraft tend to use it for just weather information that is why all large aircraft are equipped with an airborne weather radar .the airborne weather radar awr system fitted on large aircraft uses a primary radar system to look for reflections from precipitation in clouds the wetter and larger the precipitation the better the reflectivity the stronger the returns wet hail gives the best returns whereas ice crystals and dry snow do not give good radar returns stronger returns show up in red whereas weaker returns are green and yellow returns in the middle sometimes magenta is used to show areas of turbulence convective weather has bigger wetter precipitation which makes for stronger radar returns .the radar works the same as any other pulse radar by pointing in a particular direction and firing off a pulse of electromagnetic radiation in the microwave band then waiting for a reply from any potential reflections in that area it then measures the time of arrival of the reflection and uses this to calculate the distance from the target as the pulses travel at the speed of light .collision detection such as tcas is usually provided through secondary radar with pulses and replies rather than reflections exemple 295 Detecting areas of wet, convective weather.Detecting areas of wet, convective weather.

Radar has many uses in civil aviation for which tasks are both primary and ?

Question 195-2 : For atc to provide tracking of aircraft and manage traffic within a given airspace for the pilot to navigate and avoid areas of significant weather for atc to reduce the workload of the pilot by taking over the task of navigating for the pilot to detect other aircraft and reduce the risk of collision

Note this question is asking about primary and secondary radar not just one but when are both used .learning objective 062 03 01 01 01 name the different applications of radar with respect to air traffic control atc weather observations and airborne weather radar awr ..radar is an incredibly useful tool to aviation and is used in many forms for multiple different jobs in civil aviation .for starters it is split into primary and secondary radar primary radar is where a transceiver sends out electromagnetic pulses or waves that are reflected off items in the environment back to the transceiver and the time taken to travel to and from the object is measured to give an indication of its range the radar scans back and forth to figure out the direction of the object and in doing so gets a direction and distance so can plot the location on a display .secondary radar is where an interrogator sends out an interrogation signal transponders pick this signal up then send a reply signal which is good as it can carry more information such as squawk codes and altitudes as used in ssr secondary surveillance radar ..atc can use primary radar to track aircraft and weather and use secondary radar also to track aircraft and gain extra information about an aircraft ssr .pilots can use primary radar to track weather and navigate airborne weather radar as well as in the radio altimeter and can use secondary radar to detect other aircraft for collision avoidance acas/tcas as well as for dme which is technically a secondary radar system the aircraft is the interrogator exemple 299 For atc to provide tracking of aircraft and manage traffic within a given airspace.For atc to provide tracking of aircraft and manage traffic within a given airspace.

A mode s transponder knows that it is receiving interrogations from a mode s ?

Question 195-3 : Extra pulses are transmitted directly following the mode a and mode c pulses the ground interrogator will transmit extra pulses once it has had the initial reply from the airborne transponder the ground interrogator transmits the same pulses for all modes but for mode s the pulses are stronger only pulses specific to mode s are transmitted by the ground interrogator

Mode s does not transmit the p3 pulse but has an additional p4 pulse transponder without mode s will ignore p4 impulses p4 pulses can be either long or short in duration .the mode a/c/s all call interrogation elicits a mode a or mode c reply depending on the p1 p3 pulse spacing from a mode a/c transponder because it does not recognize the p4 pulse a mode s transponder recognizes the long p4 pulse and responds with a mode s reply icao annex 10 aeronautical telecommunications chapter 3 .this means that a mode s transponder transmits or receives extra pulses after the mode a and mode c transponder pulses exemple 303 Extra pulses are transmitted directly following the mode a and mode c pulses.Extra pulses are transmitted directly following the mode a and mode c pulses.

The pilot is given a 25 ft altitude increment which ssr mode does this apply to ?

Question 195-4 : Mode s mode a mode c mode a and c

Vertical performance.mode c provides pressure altitude information in addition to identification and position information compared to mode a the transponder message is reported in 100 feet increments which should be considered in terms of vertical separaction by atc .mode s has significantly better performance compared to mode c in terms of updating controller with altitude data the altitude may be reported with an accuracy of 25 feet exemple 307 Mode sMode s

A primary surveillance radar psr is capable of calculating a ?

Question 195-5 : Two dimensional position by measuring the bearing and travel time of the interrogation signal one dimensional position by measuring the bearing of the interrogation signal four dimensional position by measuring the bearing travel time height and time of the interrogation signal three dimensional position by measuring the bearing travel time and height of the interrogation signal

Refer to figure . primary surveillance radar psr primary surveillance radar psr operates by emitting radio wave pulses from a rotating antenna when these pulses encounter an aircraft or object some of the energy is reflected back to the antenna the psr uses a polar coordinate system to provide information on the detected targets it calculates the range which is the slant distance from the antenna to the target and the bearing which is determined by the antenna's azimuth range . the range is determined by comparing the time it takes for the pulse to be emitted and received utilizing the speed of light as the propagation speed it's important to note that the range provided is not the horizontal distance but the slant distance from the antenna to the target bearing . the measurement of bearing is achieved using the searchlight principle this involves concentrating radio pulses into narrow beams which can be accomplished by either shortening the wavelength or increasing the size of the aerial in advanced systems this is done electronically the narrow beam is then rotated at a constant speed when an echo is received the direction of the object is determined based on the direction of the beam at the time of receiving the echo this direction is measured from a fixed reference point or datum primary surveillance radar psr calculates bearing and range time difference of a target providing a two dimensional position exemple 311 Two-dimensional position by measuring the bearing and travel time of the interrogation signal.Two-dimensional position by measuring the bearing and travel time of the interrogation signal.

A primary route surveillance radar provides ?

Question 195-6 : Direction by measuring antenna azimuth range by signal travel during time no altitude 4 digit squawk code no direction no range no altitude altitude by angle elevation direction by antenna's angle of azimuth no range range by interrogating dme transponder altitude by interrogating mode c transponder no direction

Refer to figure . primary surveillance radar psr primary surveillance radar psr operates by emitting radio wave pulses from a rotating antenna when these pulses encounter an aircraft or object some of the energy is reflected back to the antenna the psr uses a polar coordinate system to provide information on the detected targets it calculates the range which is the slant distance from the antenna to the target and the bearing which is determined by the antenna's azimuth range . the range is determined by comparing the time it takes for the pulse to be emitted and received utilizing the speed of light as the propagation speed it's important to note that the range provided is not the horizontal distance but the slant distance from the antenna to the target bearing . bearing measurement in radar systems utilizes the searchlight principle where radio pulses are focused into narrow beams this can be achieved by reducing the wavelength or electronically enlarging the antenna in advanced systems the narrow beam is then rotated at a consistent speed by analyzing the direction of the received echo the bearing of the object can be determined based on the azimuth of the antenna at the time of receiving the echo this directional information is measured from a fixed reference point or datumprimary surveillance radar psr calculates bearing antenna's azimuth and range signal travel time of a target providing a two dimensional position altitude is not provided exemple 315 Direction by measuring antenna azimuth, range by signal travel during time, no altitude.Direction by measuring antenna azimuth, range by signal travel during time, no altitude.

A functional mode s transponder interrogated in mode a what is provided to the ?

Question 195-7 : Transponder code only transponder code and pressure altitude transponder code pressure altitude and aircraft address transponder code pressure altitude aircraft address and other flight data

The aircraft is interrogated from the ground station by a predetermined series of pulses on the carrier frequency of 1030 mhz its transponder then transmits a coded reply on a carrier frequency of 1090 mhz the modes of operation are mode a an interrogation to identify an aircraft . mode c an interrogation to obtain an automatic height read out of an aircraft referenced to 1013 hpa . mode s a development of the basic ssr fully compatible with the conventional mode a and c units providing air to ground ground to air air to air data link and height read out in increments of 25 ft mode s selective addressing . enables data exchange using communications protocols mode s data link can serve as an alternative or supplementary method for various atc services that are traditionally carried out using vhf voice communications this utilization of data link technology enhances the safety and reliability of the atc system by minimizing errors associated with voice based communication numerous types of messages and services within atc can benefit from data link backup like flight identification altitude clearance confirmation take off clearance confirmation new communication frequency for sector hand off pilot acknowledgement of atc clearance transmission to the ground of aircraft flight parameters minimum safe altitude warninga mode s transponder is fully compatible with conventional mode a and c ground units this means that if a mode s transponder is interrogated in mode a the transponder responds as if it was set in mode a providing aircraft identification transponder code to the atc radar screen exemple 319 Transponder code only.Transponder code only.

In a satellite assisted navigation system gnss/gps a fix is obtained by ?

Question 195-8 : Measuring the time taken for a minimum number of satellites' transmissions in known positions to reach the aircraft's receiver the aircraft's receiver measuring the phase angle of signals received from a number of satellites in known positions measuring the time taken for an aircraft's transmissions to travel to a number of satellites in known positions and return to the aircraft's receiver measuring the pulse lengths of signals received from a minimum number of satellites received in a specific sequential order

exemple 323 Measuring the time taken for a minimum number of satellites' transmissions, in known positions, to reach the aircraft's receiver.Measuring the time taken for a minimum number of satellites' transmissions, in known positions, to reach the aircraft's receiver.

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

Question 195-9 : 4 24 3 5

Admin .to carry out three dimensional 3d operation 4 satellites .to carry out two dimensional 2d operation 3 satellites exemple 327 4.4.

Gps satellites transmit on two l band frequencies with different types of ?

Question 195-10 : L1 coarse acquisition c/a with selected availability s/a l2 coarse acquisition c/a l1 precise p l2 for communications purpose

exemple 331 L1-coarse acquisition (c/a) with selected availability (s/a).L1-coarse acquisition (c/a) with selected availability (s/a).

Which of the following coordinate systems is used by the navstar/gps receiver ?

Question 195-11 : Wgs 84 ed 87 ed 50 pz 90

exemple 335 Wgs 84.Wgs 84.

Which of the following lists all the parameters that can be determined by a gps ?

Question 195-12 : Latitude longitude altitude and time latitude and longitude latitude longitude and time latitude longitude and altitude

exemple 339 Latitude, longitude, altitude and time.Latitude, longitude, altitude and time.

In a satellite assisted navigation system gnss/gps a position line is obtained ?

Question 195-13 : Timing the period that is taken for a satellite's transmission to reach the aircraft's receiver the aircraft's receiver measuring the phase angle of the signal received from a satellite in a known position timing the period that is taken for a transmission from the aircraft's transmitter/receiver to reach and return from a satellite in a known position the aircraft's receiver measuring the time difference between signals received from a minimum number of satellites

.the gps receiver computes the time taken for the signal to travel from the satellite to the receiver exemple 343 Timing the period that is taken for a satellite's transmission to reach the aircraft's receiver.Timing the period that is taken for a satellite's transmission to reach the aircraft's receiver.

In which frequency band do satellite assisted navigation systems gnss/gps ?

Question 195-14 : Uhf shf ehf vhf

Admin .each satellite broadcasts ranging signals on two uhf frequencies l1 1575 42 mhz and l2 1227 6 mhz .vor operating frequencies vhf.localiser vhf.marker beacon vhf.dme operating frequencies uhf.glide slope uhf.gnss/gps uhf.l1 and l2 frequencies used by navstar/gps uhf.ils localiser and glide slope vhf and uhf bands .microwave landing system mls shf.airborne weather radars shf.locator lf/mf exemple 347 Uhf.Uhf.

What is the minimum number of satellites required for the navstar/gps to carry ?

Question 195-15 : 3 24 5 2

Admin .to carry out three dimensional 3d operation 4 satellites .to carry out two dimensional 2d operation 3 satellites exemple 351 3.3.

Ignoring pulse length the maximum pulse repetition frequency prf that can be ?

Question 195-16 : 405 pps 782 pps 308 pps 810 pps

Admin .c/2f = 200nm . velocity of light = 162000 nm/sec .2f = 162000/200.2f = 810.f = 405 pps exemple 355 405 pps.405 pps.

Which of the following lists are all errors that affect the accuracy and ?

Question 195-17 : Satellite clock satellite ephemeris atmospheric propagation satellite mutual interference satellite ephemeris atmospheric propagation satellite to ground time lag atmospheric propagation satellite clock satellite mutual interference frequency drift satellite to ground time lag

exemple 359 Satellite clock; satellite ephemeris; atmospheric propagation.Satellite clock; satellite ephemeris; atmospheric propagation.

In order to carry out an independent three dimensional fix receiver autonomous ?

Question 195-18 : 6 7 5 4

Admin .raim receiver autonomous integrity monitoring is a technique whereby a receiver processor determines the integrity of the navigation signals raim is achieved by consistency check among pseudo range measurements .the basic raim requires 5 satellites but a 6th is necessary for isolating a faulty satellite from the navigation solution exemple 363 6.6.

Signal reception is required from a minimum number of satellites that have ?

Question 195-19 : 4 6 5 3

exemple 367 4.4.

The distance between a navstar/gps satellite and receiver is ?

Question 195-20 : Determined by the time taken for the signal to arrive from the satellite multiplied by the speed of light calculated from the doppler shift of the known frequencies calculated using the wgs 84 reference system from the known positions of the satellite and the receiver determined by the phase shift of the pseudo random noise code multiplied by the speed of light

Admin .the pseudorange is the pseudo distance between a satellite and a gps receiver .to determine its position a gps receiver will determine the ranges to at least four satellites as well as their positions at time of transmitting knowing the satellites' orbital parameters these positions can be calculated for any point in time the pseudoranges of each satellite are obtained by multiplying the speed of light by the time the signal has taken from the satellite to the receiver as there are accuracy errors in the time measured the term pseudo ranges is used rather than ranges for such distances exemple 371 Determined by the time taken for the signal to arrive from the satellite multiplied by the speed of light.Determined by the time taken for the signal to arrive from the satellite multiplied by the speed of light.

The reason why the measured distance between a navstar/gps satellite navigation ?

Question 195-21 : Calculated range includes receiver clock error measured distance is based on the pseudo random noise code movement of satellite and receiver during the distance calculation is not taken into account calculated range is based on an idealised keplerian orbit

Admin .satellites use an atomic clock actually 4 for high precision and continuously transmit their positions plus a code number in a set code at exactly the same time the set code appears to be random but isn't which is why it is known as pseudo random noise code it is the means by which a receiver recognises signals from a particular satellite .since the transmission time is known the distance the signal has travelled can be calculated from its arrival time the receiver matches each satellite's code with an identical copy in its database by comparing any shift with its internal clock it can calculate a pseudo range which is similar to comparing a broadcast copy of a song against one already playing on a cd player if they both started at the same time the received one would be slightly behind from the time delay if several 'songs' are received at the same time from multiple sources the gps receiver can correct for errors in its own clock and determine actual travel times .the principle used is that if three perfect measurements can locate a point in space four imperfect ones can eliminate clock offsets or cancel out some timing errors .an error is therefore deliberately introduced and algebra is used to compute where all possible points could intersect the result given is your position because it is calculated the word pseudo is used and the measured distance between a satellite and a receiver is called a pseudo range because the calculated range includes receiver clock error exemple 375 Calculated range includes receiver clock error.Calculated range includes receiver clock error.

What type of satellite navigation system navstar/gps receiver is most suitable ?

Question 195-22 : Multichannel sequential multiplex any hand held type

Admin .most gps receivers in use today are multi channel type meaning that they can track one satellite per channel a typical receiver will have 12 channels allowing it to track up to 12 satellites simultaneously .the receiver uses the latest almanac data to determine which satellites are visible at its location exemple 379 Multichannel.Multichannel.

The receiver aerial for a navstar/gps system should be mounted ?

Question 195-23 : On the upper side of the fuselage in the vicinity of the centre of gravity inside the tail fin to minimise the influence of reflections from the wing and fuselage in the vicinity of the receiver to avoid long transmission lines under the fuselage in order to receive correction data transmitted by d gps stations

exemple 383 On the upper side of the fuselage in the vicinity of the centre of gravity.On the upper side of the fuselage in the vicinity of the centre of gravity.

In the navstar/gps satellite navigation system re use of selective availability ?

Question 195-24 : Dithering the satellite clock shutting off selected satellites using a less accurate atomic clock in a satellite for signal processing offsetting satellite atomic clocks by a predetermined constant amount

.the c/a code coarse acquisition clear access or civil access is modulated on the l1 carrier only the p code precise or protected is modulated on both carriers .there are two limitations for civilian users namely selected availability and anti spoofing briefly referred to as sa and as respectively both deteriorate the achievable accuracy for civilian users significantly .selective availability sa the denial of full accuracy is accomplished by 'manipulating' navigation message orbit data epsilon and/or the satellite clock frequency dither so far only the satellite clock frequency has been manipulated with this dithering process the gps satellite clocks are artificially degraded by adding a signal with an unknown frequency and amplitude to the know clock behavior this is done to degrade the performance of gps for the 'normal' users both the frequency and amplitude of the added signal change rapidly over time the amplitude of this 'clock dithering' is of the order of 0 3 microseconds which corresponds to roughly 100 meters and the frequency is of the order of only a few minutes .this sa clock dithering limits the accuracy of real time position estimates to 25 meters rms exemple 387 Dithering the satellite clock.Dithering the satellite clock.

In the event of the re use of selective availability how does this affect if at ?

Question 195-25 : It degrades position accuracy by manipulating satellite signals it increases because only signals from satellites in the most suitable geometric constellation are selected by the receiver it has no influence because by selecting of the most suitable signals the computing process in the receiver is quicker it degrades accuracy by reducing the number of available satellites

.gps selective availability sa is a currently disabled since may 2000 function of the navstar / gps system which permits the us department of defence to downgrade the l1 signal available to unauthorised civilian users by adding intentional time varying errors to gps signals .these errors of up to 100 meters 328 ft to the l1 signals were intended to deny the use of civilian gps receivers for precision weapon guidance although typical sa errors were 10 meters 32 ft horizontally and 30 meters 98 ft vertically exemple 391 It degrades position accuracy by manipulating satellite signals.It degrades position accuracy by manipulating satellite signals.

In the navstar/gps satellite navigation system receiver clock error ?

Question 195-26 : Is corrected by using signals from four satellites is the biggest part of the total error it cannot be corrected can be minimised by synchronisation of the receiver clock with the satellite clocks is negligible small because of the great accuracy the atomic clocks installed in the satellites

One of the most significant error sources is the gps receiver's clock because of the very large value of the speed of light c the estimated distances from the gps receiver to the satellites the pseudoranges are very sensitive to errors in the gps receiver clock for example an error of one microsecond 0 000 001 second corresponds to an error of 300 metres 980 ft this suggests that an extremely accurate and expensive clock is required for the gps receiver to work since manufacturers prefer to build inexpensive gps receivers for mass markets the solution for this dilemma is based on the way sphere surfaces intersect in the gps problem .it is likely that the surfaces of the three spheres intersect since the circle of intersection of the first two spheres is normally quite large and thus the third sphere surface is likely to intersect this large circle it is very unlikely that the surface of the sphere corresponding to the fourth satellite will intersect either of the two points of intersection of the first three since any clock error could cause it to miss intersecting a point however the distance from the valid estimate of gps receiver position to the surface of the sphere corresponding to the fourth satellite can be used to compute a clock correction exemple 395 Is corrected by using signals from four satellites.Is corrected by using signals from four satellites.

The influence of the ionosphere on the accuracy of the satellite navigation ?

Question 195-27 : Minimised by the receiver using a model of the atmosphere and comparing signals transmitted by the satellites minimised by computing the average of all signals only significant if the satellites are located at a small elevation angle above the horizon negligible

exemple 399 Minimised by the receiver using a model of the atmosphere and comparing signals transmitted by the satellites.Minimised by the receiver using a model of the atmosphere and comparing signals transmitted by the satellites.

What are the effects if any of shadowing by parts of the aircraft e g wing on ?

Question 195-28 : It may prevent the reception of signals it causes multipath propagation the signals will be distorted however the error can be corrected for using an algorithm and information from unaffected signals it has no influence because high frequency signals are unaffected

Admin .gps satellites transmit a low powered radio signal that travels by line of sight this means it will pass through clouds glass or plastic but will not go through most solid objects such as a wing it will no longer be able to provide the user with a current location until it can resume a link to at least three satellites and then update its position exemple 403 It may prevent the reception of signals.It may prevent the reception of signals.

Which of the following geometric satellite constellations provides the most ?

Question 195-29 : 3 satellites with a low elevation above the horizon and an azimuth of 120° from each other together with a fourth directly overhead 3 satellites with an azimuth of 120° from each other and an elevation of 45° above the horizon 4 satellites with an azimuth of 90° from each other and a low elevation above the horizon 4 satellites with an azimuth of 90° from each other and an elevation of 45° above the horizon

Admin . 2605 exemple 407 3 satellites with a low elevation above the horizon and an azimuth of 120° from each other together with a fourth directly overhead.3 satellites with a low elevation above the horizon and an azimuth of 120° from each other together with a fourth directly overhead.

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

Question 195-30 : Fixed ground stations compute position errors and transmit correction data to a suitable receiver on the aircraft 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 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

exemple 411 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.

Which of the following statements about the accuracy that can be obtained with ?

Question 195-31 : The nearer a receiver is situated to a d gps ground station the more accurate the position fix only d gps allows position fixes accurate enough for 'non precision approaches' the increase in accuracy of position fixes is independent of the receiver position in relation to a d gps ground station a d gps receiver can detect and correct for sa providing a more accurate position fix

exemple 415 The nearer a receiver is situated to a d-gps ground station, the more accurate the position fix.The nearer a receiver is situated to a d-gps ground station, the more accurate the position fix.

How does a receiver of the navstar/gps satellite navigation system determine ?

Question 195-32 : It calculates it by using almanac data transmitted by the satellites the data is stored in the receiver together with the pseudo random noise prn code the data is based on the direction to the satellite determined at the location of the antenna the data is determined by the satellite and transmitted together with the navigation message

exemple 419 It calculates it by using almanac data transmitted by the satellites.It calculates it by using almanac data transmitted by the satellites.

In relation to the navstar/gps satellite navigation system 'search the sky' is a ?

Question 195-33 : Procedure that starts after switching on a receiver if there is no stored satellite data available continuous process by the ground segment to monitor the gps satellites procedure performed by the receiver to recognise new satellites becoming operational continuous procedure performed by the receiver that searches the sky for satellites rising above the horizon

exemple 423 Procedure that starts after switching on a receiver if there is no stored satellite data available.Procedure that starts after switching on a receiver if there is no stored satellite data available.

Which of the following if any is a prerequisite if a receiver of a navstar/gps ?

Question 195-34 : The prescribed ifr equipment must be installed and operational the prescribed ifr equipment must be in working correctly and the navigation information continuously displayed the raim function of the gps receiver must be able to monitor all prescribed navigation systems multi sensor systems are not certificated for flights under ifr conditions

exemple 427 The prescribed ifr-equipment must be installed and operational.The prescribed ifr-equipment must be installed and operational.

Which of the following is the datum for altitude information when conducting ?

Question 195-35 : Barometric altitude the average of gps altitude and barometric altitude gps altitude gps altitude if 4 or more satellites are received otherwise barometric altitude

.icao doc 8168 part ii section 3 chapter 1 .all fmcs and some stand alone basic gnss receivers provide altitude information .however the pilot must still comply with the published minimum altitudes using the barometric altimeter where the fmc provides vertical information flight director guidance cues or coupled autopilot operation the pilot should follow the appropriate information or cues along with any necessary cross checks with the barometric altimetry exemple 431 Barometric altitude.Barometric altitude.

Which of the following statements about the 'visibility' of navstar/gps ?

Question 195-36 : It varies depending on the time and observer's location it is the same throughout the globe it is greatest at the equator it is greatest at the poles

exemple 435 It varies, depending on the time and observer's location.It varies, depending on the time and observer's location.

How many operational satellites are required for full operational capability ?

Question 195-37 : 24 18 12 30

exemple 439 24.24.

Which of the following satellite navigation systems has full operational ?

Question 195-38 : Navstar/gps nnss transit cospas sarsat glonass

Admin .there are two main global navigation satellite systems gnss currently in existence with a third which is planned to be fully operational by 2012 they are . usa navstar gps navigation system with timing and ranging global positioning system . russian glonass global navigation satelitte system . european galileo .currently only navstar/gps satellite navigation system is approved for specified flights under ifr conditions in europe exemple 443 Navstar/gps.Navstar/gps.

Gps system satellites transmit their signals on two carrier waves 1575 mhz and ?

Question 195-39 : Only the 1575 mhz carrier wave and one code only the 1575 mhz carrier wave and two codes only the 1227 mhz carrier wave and one code the two carrier waves and one public code

Admin .each satellite broadcasts ranging signals on two uhf frequencies . l1 1575 42 mhz .l2 1227 6 mhz.there are currently two modes of operation sps standard positioning service for civilian users and pps precise positioning service for authorised users . sps is a positioning and timing service provided only on frequency l1 .sps was originally designed to provide civil users with a less accurate positioning capability than pps .pps uses both frequencies l1 and l2 exemple 447 Only the 1575 mhz carrier wave and one code.Only the 1575 mhz carrier wave and one code.

Which statement about dilution of precision dop is correct ?

Question 195-40 : The value of dop depends upon the geometry and number of satellites in view the value of dop depends upon the accuracy with which the range between satellite and receiver can be measured the value of dop depends upon the availability of abas the value of dop depends upon the availability of raim software in the gps receiver

Admin .the position dilution of precision pdop is the geometric effect resulting from satellites being too close together satellites that appear farther apart in the sky provide a more accurate position solution than ones close together in the latter case the position accuracy is degraded in a similar fashion to when position lines from ground based navaids navigational aids are less than 45° since the ephemeris of each satellite is known by the gps global positioning system receiver it is possible to calculate which combination of gps satellites provides the best geometry at a given time this is translated into a figure called the position dilution of precision pdop since the satellites move across the sky relative to the user the pdop is always changing a low pdop is better a pdop of 4 to 6 is considered good position solutions calculated when the pdop is from 6 to 10 should be used cautiously because they may have significant error a pdop that is above 10 indicates unacceptable error .the icao international civil aviation organization states that a pdop of less than 6 is required for en route navigation with a pdop of 3 or less required for nonprecision approaches i e not ils types exemple 451 The value of dop depends upon the geometry and number of satellites in view.The value of dop depends upon the geometry and number of satellites in view.

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