FUNDAMENTAL SURVEYING Surveying Equipment & GPS/GNSS 2

Question 1

What is 'DOP' (Dilution of Precision) in GPS surveying?

Accepted Answer

A dimensionless number indicating the geometric strength of the satellite configuration

Answer

The percentage of time a GPS receiver is operational

Answer

The signal delay caused by the ionosphere

Answer

The number of satellites in a constellation

Question 2

Which type of GPS error is largely eliminated by differential techniques (DGPS or RTK)?

Accepted Answer

Common-mode atmospheric errors that affect both base and rover

Answer

Antenna phase center variation

Answer

Multipath from nearby reflective surfaces

Answer

Receiver clock drift in the rover only

Question 3

What is 'geodetic height' (ellipsoidal height) in GPS terminology?

Accepted Answer

The height above the reference ellipsoid (GRS 80 or WGS 84)

Answer

The elevation above mean sea level (orthometric height)

Answer

The height above the local geoid only

Answer

The height corrected for atmospheric refraction

Question 4

What is a 'tribrach' in surveying instrumentation?

Accepted Answer

A leveling base with three foot screws that mounts instruments on a tripod head

Answer

A three-legged rod used to hold a prism over a point

Answer

A three-crosshair reticle used in precise leveling

Answer

A type of tripod with only three sections

Question 5

What is 'forced centering' in surveying?

Accepted Answer

A system allowing interchangeable instruments to be swapped onto a tribrach without re-centering over the point

Answer

A method to force-close a traverse with excess error

Answer

The process of centering a level bubble electronically

Answer

A GPS initialization method for RTK surveys

Question 6

What is the purpose of atmospheric corrections applied to EDM measurements?

Accepted Answer

To adjust the velocity of electromagnetic waves for actual air temperature, pressure, and humidity

Answer

To correct for the curvature of the Earth along the measurement path

Answer

To compensate for the magnetic effect of the atmosphere on the prism

Answer

To reduce slope distance to horizontal distance