PS GNSS & RTK Survey Technology 3

Question 1

The NMEA 0183 GGA sentence provides which of the following fields critical for RTK status monitoring?

Accepted Answer

Fix quality indicator, number of satellites, and HDOP

Answer

The GGA sentence includes fix quality (0=invalid, 1=GPS, 2=DGPS, 4=RTK fixed, 5=RTK float), satellite count, HDOP, and antenna height.

Question 2

What is the typical horizontal accuracy specification for a high-quality RTK GNSS receiver under good conditions?

Accepted Answer

±1–2 cm + 1 ppm

Answer

RTK systems commonly achieve ±1–2 cm horizontal accuracy with an additional parts-per-million component that grows with baseline length.

Question 3

A surveyor observes that satellite signals arrive at the antenna via reflected paths off nearby buildings. This error source is called:

Accepted Answer

Multipath

Answer

Multipath occurs when GNSS signals reflect off surfaces and arrive at the antenna via multiple paths, distorting code and carrier phase measurements.

Question 4

In GNSS carrier-phase surveying, an abrupt jump in the measured phase due to brief loss of signal lock is called a:

Accepted Answer

Cycle slip

Answer

A cycle slip is a discontinuity in the carrier-phase observable caused by momentary loss of lock, resulting in an integer jump in the ambiguity.

Question 5

When initializing an RTK rover, what is the minimum recommended number of common satellites between base and rover for a reliable fixed solution?

Accepted Answer

5

Answer

At least 5 common satellites are generally required for reliable RTK initialization, providing sufficient redundancy for ambiguity resolution.

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