(CH. 6 Canvas Material) Major Test B Study Guide - SRVY 2331

Material pulled from Canvas to make a study guide

What is static GNSS surveying?

A relative positioning method where multiple stationary receivers collect data simultaneously

What is the preferred GNSS method for control surveys?

Static GNSS surveying

What are the minimum requirements for a static GNSS survey?

More than one receiver, at least 4 satellites, and a mostly open sky

How long do static GNSS sessions typically last?

About 30 minutes to 2 or more hours

What is the result of static GNSS processing?

Baselines or vectors between receivers

What is the difference between precision and accuracy?

Precision is how tightly measurements cluster, accuracy is how close they are to the true value

What is local accuracy?

Uncertainty relative to adjacent connected points

What is network accuracy?

Uncertainty relative to a datum such as the NSRS

Which is usually larger, horizontal or vertical uncertainty?

Vertical uncertainty

What does CORS stand for?

Continuously Operating Reference Station

What is the main advantage of using CORS?

Relative positioning without running your own base station

What does ARP stand for?

Antenna Reference Point

What is the ARP?

The physically measurable antenna reference point

What is PDOP?

Position Dilution of Precision, a measure of satellite geometry

What does a low PDOP indicate?

Good satellite geometry

What PDOP value is considered excellent?

Less than 2

What PDOP value should generally be avoided?

About 5 to 6

What mask angle is commonly used in static GNSS surveying?

15° to 20°

Why are multifrequency receivers preferred on long baselines?

They nearly eliminate ionospheric error

What baseline length is generally suitable for single-frequency receivers?

Less than about 25 km

What is multipath?

A reflected GNSS signal that reaches the antenna by more than one path

What types of objects commonly cause multipath?

Metal structures, chain-link fences, parked vehicles, and trains

How can multipath be reduced?

Using choke ring antennas, survey masts, and offset points

What is a zero-baseline test?

Two receivers connected to one antenna through a splitter

What errors are removed in a zero-baseline test?

Clock, orbit, atmospheric, and multipath errors

What should a zero-baseline test result be?

Only a few millimeters

How many independent baselines are produced in one session?

r − 1, where r is the number of receivers

With 4 receivers, how many independent baselines are there?

3

What creates redundancy in a GNSS network?

Repeated independent baselines and reoccupied stations

What is a cycle slip?

A loss of carrier-phase lock that changes the integer ambiguity

Why should every baseline be part of a loop?

To provide redundancy and checking

What is the most common GNSS field blunder?

Incorrect antenna height, H.I., measurement

How should antenna height be measured?

Independently in both feet and meters, not by conversion

Why are all GNSS antennas usually oriented the same direction, typically north?

To reduce phase center variation effects

What does GNSS directly provide, ellipsoidal or orthometric heights?

Ellipsoidal heights

What method is best for transferring orthometric heights?

Spirit leveling

What information should always be checked before planning observations?

Satellite health and PDOP

What format is used for CORS data distribution?

RINEX

What does PID stand for on an NGS data sheet?

Permanent Identifier

What does a Laplace correction do?

Converts astronomic azimuth to geodetic azimuth

What does HTDP do?

Computes coordinates at different epochs