PS Surveying Equipment & Technology 3

Question 1

What is the function of the 'circle zero set' procedure performed before taking angular measurements with a theodolite?

Accepted Answer

Orients the horizontal circle to a desired initial direction

Answer

Circle zero set (or circle set) positions the horizontal circle so that a reference backsight direction reads a predetermined value, typically 0°00'00".

Question 2

In static GNSS baseline processing, what is the significance of 'fixing the integer ambiguity'?

Accepted Answer

Resolving the unknown whole number of carrier wave cycles between satellite and receiver to achieve centimeter accuracy

Answer

Fixing integer ambiguities allows use of the precise carrier phase measurement rather than pseudo-range, yielding sub-centimeter baseline precision.

Question 3

Which instrument is best suited for establishing precise vertical control along a long highway corridor where differential leveling would be impractical?

Accepted Answer

Network RTK GNSS with accurate geoid model

Answer

Network RTK GNSS combined with a high-accuracy geoid model (e.g., GEOID18) can provide rapid orthometric heights accurate to 2–3 cm over long corridors.

Question 4

What is the primary drawback of using a 360° prism (omnidirectional prism) with a robotic total station?

Accepted Answer

Its effective prism constant varies with the angle of incidence, introducing distance errors

Answer

Because the signal enters a 360° prism from varying angles as the target moves, the effective prism constant changes slightly, introducing small but real distance errors if not properly modeled.

Question 5

A terrestrial laser scanner reports a range noise of ±2 mm at 50 m. What is the primary source of this random range error?

Accepted Answer

Signal-to-noise ratio in the detector circuit and surface reflectivity variation

Answer

Range noise in TLS systems is dominated by detector noise and target reflectivity; darker or angled surfaces return fewer photons, increasing measurement uncertainty.

(PS) Professional Licensed Surveyor Practice Test

(PS) Professional Licensed Surveyor Practice Test

PS Surveying Equipment & Technology 3