Thales Z-Max Operation And Application Manual page 242

using a single epoch of base station data to compute multiple rover RTK positions.
The default is Coarse Positioning.
Choosing between Fast RTK and Synchronized RTK
Choosing between Fast (Coarse) and Synchronized (Fine) RTK can be confusing.
This section will explain how Synchronized and Fast RTK work, and provide
applications where you might choose one over the other. Choosing the right mode for
your application is a decision based on a trade-off between frequency of the position
output, and the accuracy of the position.
Synchronized RTK
Synchronized RTK or Fine Positioning is generally less consistent in its output but
more consistent in its accuracy that Fast RTK or Coarse Positioning. Synchronized
RTK is used when consistent accuracy is more important than the frequency of
position output.
In Synchronized RTK, the rover receiver will compute and output a single RTK rover
position for each DBEN, RTCM, or CMR message it receives from the base receiver.
In synchronized RTK, the maximum transmission rate from the base receiver is 1 Hz
(once per second). If the H option is enabled the maximum transmission rate can be
set to 5 Hz (5 times per second). The maximum position output rate at the remote
receiver is equal to the data transmission rate at the base station. In other words, if
the base station data is transmitting data at 1 Hz, then the rover can output RTK
positions at a maximum rate of 1 Hz.
Fine positioning is less consistent in its output because any interruption in the rover
station's reception of base data will cause the rover to cease outputting positions. An
interruption could be caused by a problem at the base receiver or interference in the
data link between the base and the rover. Regardless of the cause, the rover will only
provide an RTK position when it receives data from the base receiver. So if base data
is blocked for 5 seconds, then the rover will cease to output a position for 5 seconds.
Synchronized RTK is generally more accurate because of the issue of latency.
Latency is the delay between when raw base data is transmitted from the base, and
when the data is used in a rover position computation. Latency degrades position
accuracy so the higher the latency, the less accurate the RTK position. With
synchronized RTK, the latency of the rover position is very small so the positions are
consistently very accurate. The accuracy of synchronized RTK positions is typically
0.5 cm + 1ppm.
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