SATELLITE GEODESY CORRE

(d)

It is the number of waves that pass a fixed point in unit time; also, the number of cycles or vibrations undergone during one unit of time by a body in periodic motion.

(a) wavelength

(b) amplitude

(c) period

(d) frequency

(a)

The _________ of a wave is the point on the medium that exhibits the maximum amount of negative or downward displacement from the rest position.

(a) trough

(b) crest

(c) frequency

(d) amplitude

(e)

Satellite navigation relies on electromagnetic waves, whose characteristics are described by __________. Oscillating electric or magnetic forces generate the __________.

(a) Planck's equations, field

(b) Planck's equations, waves

(c) Maxwell's equations, frequency

(d) Maxwell's equations, photons

(e) Maxwell's equations, waves

(a)

A periodic wave which can be modeled by a __________ in space and time is a __________.

(a) sinusoidal function, sinusoidal wave

(b) sine function, frequency

(c) cosine function, period

(d) cosine function, wavelength

(e) sinusoidal function, period

(a)

___________ can be defined as the distance between two successive crests or troughs of a wave.

(a) Wavelength

(b) Amplitude

(c) Period

(d) Frequency

(b)

___________ means the practical realization of a reference system through observations. It consists of a set of identifiable fiducial points on the sky or on Earth's surface. It is described by a catalogue of precise positions and motions (if measurable) at a specific epoch.

(a) Reference sytems

(b) Reference frames

(c) Earth's orientation parameter

(d) Doppler positioning

(d)

The of a heavenly body is the angular distance (measured along the hour circle) between the body and the equator; it is plus when the body is north of the equator and minus when south of it.

(a) latitude

(b) altitude

(c) polar distance (d) declination

(a)

is a supermassive black hole feeding on gas at the center of a distant galaxy. (a) Quasar (b) Pulsar (c) Galaxy (d) Blazar

(b)

In satellite telecommunication, is the link from a ground station up to a satellite. (a) downlink (b) uplink (c) adaptive coding and modulation (d) band switching

(a)

The closest point a satellite comes to Earth is called its (a) perigee (b) apogee (c) aphelion (d) perihelion

(b)

means moving the spacecraft out of the launch vehicle and into the right orbit or trajectory. (a) Launch (b) Deployment (c) Integration (d) Propulsion

(d)

The initiated in 1987 and exclusively based on space techniques, provides highly accurate Earth orientation parameters with high temporal resolution, and maintains and constantly refines two basic reference frames (ITRF and ICRF). (a) Federation of Astronomical & Geophysical Services (b) International Association of Geodesy (c) International Union of Geodesy and Geophysics (d) International Earth Rotation Service

(a)

spacecraft was the first artificial satellite successfully placed in orbit around the Earth and was launched from Baikonur Cosmodrome at Tyuratam in Kazakhstan. (a) SPUTNIK-1 (b) EXPLORER -1 (c) TRANSIT-1B (d) ECHO-1

(a)

Diwata-1 is a Philippine microsatellite deployed into orbit from the International Space Station (ISS) on (a) April 27, 2016 (b) August 17, 2015 (c) March 12, 2015 (d) August 12, 2017

(c)

is a regular, repeating path that one object in space takes around another one. (a) Revolution (b) Rotation (c) Orbit (d) Eccentricity

(b)

Who was the first human to travel to space? (a) Neil Armstrong (b) Yuri Gagarin (c) Buzz Aldrin (d) Valentina Tereshkova

(d)

Kepler's third law stated that the periods of the planets are proportional to the 3/2 major axis lengths of their orbits. (a) 5/4 (b) 3/4 (c) 1/2 (d) 3/2

(c)

is a net force that acts on an object to keep it moving along a circular path. (a) Normal force (b) Coriolis force (c) Centripetal force (d) Centrifugal force

(a)

powers of the, a circular orbit 35,785 km (22,236 miles) above Earth's Equator in which a satellite's orbital period is equal to Earth's rotation period of 23 hours and 56 minutes. (a) Geostationary orbit (b) Polar orbit and sun-synchronous orbit (c) Medium Earth Orbit (d) Low Earth Orbit

(e)

Newton showed that for a body acted on by an attractive force proportional to 1/r^2, the only possible closed orbits are (a) 1/r a circle or an ellipse (b) 1/r hyperbola or an ellipse (c) 1/r^2, hyperbola or an ellipse (d) 1/r a circle or parabola (e) 1/r^2, a circle or an ellipse

(b)

In orbit determination, the satellite clock biases and other parameters are neglected to emphasize the actual orbit determination which is performed in two steps. First, a is fitted to the observations. In the second step, this serves as reference for the subsequent improvement of the orbit by taking into account. (a) Kepler ellipse, clock, perturbing accelerations (b) Kepler ellipse, ellipse, perturbing accelerations (c) perturbation, ellipse, atmospheric drag (d) parabola, parabola, atmospheric drag (e) parabola, ellipse, direct and Earth-reflected solar radiation pressure

(a)

The of a heavenly body is the angular distance measured eastward from the hour circle through the vernal equinox to the hour circle of a celestial body. (a) right ascension (b) greenwich hour angle (c) sidereal hour angle (d) local hour angle

(e)

The time interval between two consecutive phenomena forms the scale measure of the particular time scale. A certain multiple or fraction of the scale measure is called the is used as the basic time unit. In general, the is used as the basic time unit. (a) datation, epoch (b) datation, second(s) (c) epoch, time unit (d) datation, time unit (e) time unit, second(s)

(c)

Universal time (UT) is defined by the Greenwich hour angle augmented by 12 hours of a fictitious sun uniformly orbiting in the. Sidereal time is defined by the hour angle of the in the. (a) horizon plane, equatorial plane (b) hour angle, vernal equinox (c) equatorial plane, vernal equinox (d) equatorial plane, horizon (e) equinoctial colure, equatorial plane

(b)

Both perigee and apogee lie on the of the orbital ellipse, called the line of. (a) semi-minor axis, apsides (b) semi-major axis, apsides (c) semi-major axis, eccentricity (d) semi-minor axis, flattening (e) ascending node, inclination

(d)

The second, symbol s, is the SI unit of time. It is defined by taking the fixed numerical value of the caesium frequency delta V_CS the unperturbed ground-state hyperfine transition frequency of the atom, to be 9 192 631 770 when expressed in the unit Hz, which is equal to s^-1. (a) rubidium, 9 190 631 770 (b) rubidium, 9 912 631 770 (c) cesium-133, 9 192 613 770 (d) cesium-133, 9 192 631 770 (e) cesium-133, 9 192 631 007

(c)

Maya-1 was the first nanosatellite of the Philippines. (a) Agila-1 (b) Diwata-2 (c) Maya-1 (d) Kompsat

(a)

Revolution refers the object's orbital motion around another object. (a) Revolution (b) Rotation (c) Orbit (d) Propulsion

(c)

Which of the following is NOT a natural satellite? (a) The Moon (b) Jupiter's Europa (c) The International Space Station (d) Saturn's Titan

(a)

Which of the following statements is CORRECT about the difference between a satellite and an orbit? (a) A satellite is the object that is orbiting, and an orbit is the path that the satellite takes. (b) A satellite is the path that an object takes as it revolves around another object, and an orbit is the object that is orbiting. (c) A satellite is a natural object that orbits another object, and an orbit is an artificial object that orbits another object. (d) A satellite is a type of orbit, and an orbit is a type of satellite.

(c)

Which of the following is NOT a technique used in satellite geodesy? (a) Global Navigation Satellite System (GNSS) (b) Satellite Laser Ranging (SLR) (c) Magnetic resonance imaging (MRI) (d) Very Long Baseline Interferometry (VLBI)

(a)

Which of the following is the definition of the phase angle of a sinusoidal function? (a) The horizontal shift of the function from its standard position. (b) The vertical shift of the function from its standard position. (c) The amplitude of the function. (d) The period of the function.

(d)

Which of the following is the definition of the angular velocity of a sinusoidal function? (a) The rate of change of amplitude. (b) The vertical shift of the function from its standard position. (c) The phase angle of the function. (d) The rate of change of the phase angle.

(c)

A signal is an electromagnetic or electrical current that carries data from one system or network to another. In electronics, a signal is often a time-varying voltage that is also an electromagnetic wave carrying information, though it can take on other forms, such as current. (a) amplitude (b) resistance (c) signal (d) wavelength

(d)

The standard unit of a wave period is in seconds, and it is inversely proportional to the frequency of a wave, which is the number of cycles of waves that occur in one second. (a) continued proportion (b) compound proportion (c) directly proportional (d) inversely proportional

(a)

Magnetic fields are created by the movement of electric charges. It can also be created by electric currents. (a) Magnetic fields (b) Signal (c) Electric fields (d) Potential energy

(c)

Argument of perigee is the angle between the ascending node and perigee directions, measured along the orbital plane. (a) GHA of vernal equinox (b) Inclination (c) Argument of perigee (d) Right ascension of ascending node

(c)

Precession is a slow, steady wobble that takes about 25,772 years to complete one cycle. (a) Aberration (b) Nutation (c) Precession (d) Parallax

(b)

Polar motion is the motion of the Earth's rotational axis relative to its crust. This is measured with respect to a reference frame in which the solid Earth is fixed (a so-called Earth-centered, Earth-fixed or ECEF reference frame). This variation is a few meters on the surface of the Earth. (a) Precession (b) Polar motion (c) Nutation (d) Refraction

(a)

Aphelion is the point of the Earth's orbit that is farthest away from the Sun. (a) Aphelion (b) Perihelion (c) Apogee (d) Perigee

(b)

Ecliptic plane is defined as the imaginary plane containing the Earth's orbit around the sun. (a) Celestial equator (b) Ecliptic plane (c) Revolution (d) Declination

(a)

Orbit perturbation is any change in the orbit of a celestial object caused by external forces. These forces can include the gravitational pull of other objects, such as planets, moons, and stars, as well as atmospheric drag and solar radiation. (a) Orbit perturbation (b) Precession (c) Nutation (d) Parallax

(d)

Which of the following is NOT a law of planetary motion discovered by Johannes Kepler? (a) Planets orbit the Sun in elliptical orbits. (b) The radius vector joining a planet to the Sun sweeps out equal areas in equal intervals of time. (c) The square of the period of a planet's orbit is proportional to the cube of the semi-major axis of its orbit. (d) Planets orbit the Sun in circular orbits at a constant distance.

(a)

A geostationary orbit is a type of geosynchronous orbit that is circular and equatorial. (a) Is circular and equatorial. (b) Is elliptical and inclined. (c) Is circular and inclined. (d) Is elliptical and equatorial.

(c)

Which of the following is NOT a characteristic of a low Earth orbit? (a) Altitude of 160-2,000 kilometers (99-1,243 miles) (b) Orbital period of 90-120 minutes (c) Geostationary (d) High velocity (7-8 kilometers per second)

(d)

Solid Earth tides are the deformation of the Earth's solid surface caused by the gravitational pull of the Moon and Sun. The Earth's crust is elastic, so it deforms slightly in response to these gravitational forces. (a) Glaciology (b) Polar motion (c) Geodynamics (d) Solid Earth tides

(c)

EXPLORER-1 was a major achievement for the United States and the space program. It was the first American satellite to be successfully launched into orbit, and it provided valuable data about the Earth's environment and cosmic rays. (a) ECHO-1 (b) TRANSIT-1B (c) EXPLORER-1 (d) ANNA-1B

(b)

Which of the following statements is FALSE about the Quasi-Zenith Satellite System (QZSS)? (a) It is a regional augmentation system to GPS, focusing on Japan and surrounding areas. (b) It utilizes three geostationary satellites to improve positioning accuracy and signal availability. (c) It broadcasts correction data for improving satellite clock errors and atmospheric delays. (d) It offers enhanced positioning accuracy compared to standard GPS in urban environments.

(c)

How many satellites make up the GLONASS constellation? (a) 12 (b) 18 (c) 24 (d) 30

(b)

Which of the following procedures do kinematic GPS, DGPS, and RTK have in common? (a) Each method uses a radio link between the base station and the rover or rovers. (b) Each method uses a base station and rover arrangement. (c) Each method must maintain continuous lock on at least 4 satellites for continuous uninterrupted positioning. (d) Each method's results must be postprocessed.

(b)

In GNSS static observation, what is the primary objective of collecting data? (a) Real-time navigation (b) High-precision positioning over an extended period (c) Rapid point-to-point measurements (d) Dynamic motion analysis

(b)

In GNSS static observation, what type of receiver is commonly used for maximum accuracy? (a) Single-frequency receiver (b) Dual-frequency receiver (c) Multi-frequency receiver (d) Quad-frequency receiver

(b)

In RTK observation, what is the role of the base station? (a) Collecting dynamic motion data (b) Providing real-time correction data to the rover (c) Storing observation data for post-processing (d) Transmitting satellite signals to the rover

(b)

What challenge does multipath interference pose in GNSS RTK observation? (a) Reduced accuracy in dynamic positioning (b) Signal reflections causing measurement errors (c) Limited coverage in urban environments (d) Difficulty in establishing a communication link

(c)

How does the PRN code differentiate signals from different satellites in a GNSS constellation? (a) Each satellite transmits a unique frequency (b) Each satellite has a distinct orbital period (c) Each satellite broadcasts a unique PRN code sequence (d) Each satellite has a specific color identifier

(c)

What type of information does a GNSS almanac provide compared to an ephemeris? (a) Identical information with higher precision (b) More detailed information about satellite health and transmission details (c) Less precise but longer-term predictions of satellite positions and orbital parameters (d) Information about ground stations or reference points in the GNSS network

(d)

Which of the following statements is NOT TRUE about the Doppler effect in GNSS? (a) The Doppler effect causes a shift in the frequency of the GNSS signal depending on the relative motion between the satellite and the receiver (b) The magnitude of the Doppler shift is proportional to the relative velocity between the satellite and the receiver (c) The Doppler effect can be used to estimate the user's velocity in three dimensions (latitude, longitude, and altitude) (d) The Doppler effect only affects the carrier phase of the GNSS signal, not the pseudo-range measurement

(b)

Which of the following statements is NOT true about the relationship between wavelength and frequency in GNSS signals? (a) The wavelength and frequency of a GNSS signal are inversely proportional (b) Higher frequency signals generally have shorter wavelengths and offer better multipath mitigation (c) Different GNSS constellations utilize different frequency bands for signal transmission (d) Both wavelength and frequency are crucial for calculating pseudo-ranges and carrier phase measurements

(c)

In GNSS, what is the primary purpose of ephemeris data? (a) To encode satellite identification information (b) To synchronize the receiver's clock with the satellite's clock (c) To provide information about the satellite's orbit and position (d) To minimize the impact of multipath interference

(c)

How does double differencing mitigate the impact of common errors in GNSS measurements? (a) By introducing additional errors (b) By amplifying existing errors (c) By canceling out common errors (d) By randomly distributing errors

(b)

How does double differencing work in practice? (a) It directly removes satellite clock errors from the pseudo-range measurements (b) It subtracts pseudo-range measurements from two receivers at different locations (c) It requires complex mathematical calculations involving carrier phase data (d) It only works with specific GNSS constellations and signal frequencies

(c)

How does the choice of GNSS signal frequency affect the accuracy of pseudo-range measurements? (a) Higher frequency signals always lead to more accurate pseudo-range measurements (b) Lower frequency signals are inherently more accurate due to their longer wavelength (c) The impact on accuracy depends on various factors like satellite geometry, signal strength, and multipath effects (d) Frequency choice has no direct influence on pseudo-range accuracy; only carrier phase measurements are affected

(c)

When is it crucial for a GNSS receiver to rely on almanac data instead of ephemeris? (a) When operating in a remote location with limited satellite visibility (b) When requiring high-precision positioning for surveying or mapping applications (c) When the receiver has been inactive for a prolonged period and needs initial satellite acquisition (d) When experiencing signal interference or data corruption from the ephemeris broadcast

(a)

How are GNSS receivers able to acquire and synchronize with specific PRN codes? (a) By matching the received code sequence with a pre-loaded library (b) By comparing the signal strength of different satellites (c) By analyzing the Doppler shift of the received signal (d) By directly measuring the satellite position in the sky

(a)

What is the primary function of a CORS network? (a) Provide real-time positioning corrections for mobile GNSS receivers (b) Track and monitor satellite health and orbit information (c) Store and archive historical GNSS data for scientific research (d) Act as a redundant backup system for existing GNSS stations

(a)

How can CORS data be accessed by GNSS users? (a) Through subscription-based services (b) By physically visiting each CORS station (c) By connecting directly to the satellite signals (d) Only through government agencies

(b)

What does WAAS stand for in the context of GNSS? (a) Worldwide Auxiliary Satellite System (b) Wide Area Augmentation System (c) Wireless Aircraft Altimeter System (d) Weather Analysis and Awareness System

(b)

What type of information is included in WAAS corrections? (a) Pseudo-range corrections only (b) Satellite clock error corrections and satellite health flags (c) Carrier phase ambiguity resolution information (d) Atmospheric delay corrections

(c)

How many operational satellites are typically in the BeiDou Navigation Satellite System (BDS) constellation? (a) 10 (b) 20 (c) 30 (d) 40

(b)

What is the relationship between PDOP and the accuracy of GNSS positioning? (a) Higher PDOP values indicate higher positioning accuracy (b) Lower PDOP values indicate better geometric distribution of satellites, leading to higher positioning accuracy (c) PDOP only affects the accuracy of pseudo-range measurements (d) PDOP is unrelated to GNSS positioning accuracy

(c)

How many subframes are present within a GPS data frame? (a) 10 (b) 15 (c) 25 (d) 30

(b)

What primary components of the troposphere contribute to atmospheric delays in GNSS signals? (a) Ozone and carbon dioxide (b) Water vapor and pressure gradients (c) Nitrogen and oxygen (d) Dust and aerosols

(b)

What was Selective Availability (SA) in the context of GNSS? (a) A feature that allowed users to selectively enable or disable satellite signals (b) An intentional degradation of GPS signals by introducing errors (c) A method for selecting the best available satellite signals (d) A security feature to prevent unauthorized access to GNSS signals

(b)

What are the limitations of pseudo-range measurements in GNSS? (a) They are inherently very accurate and require no correction (b) They are affected by satellite clock errors, atmospheric delays, and multipath effects (c) They only work with specific GNSS constellations and signal frequencies (d) They are highly susceptible to interference from other radio sources