Trimble Outdoors 5700 - Manual (Page 110)

8 Real-Time Kinematic (RTK) Surveying
9 4 5700 GPS Receiver User Guide
Appl
icatio
ns
RTCM messages were designed by the Radio Technical Commission
for Maritime Services (RTCM). RTK messages were included in
version 2.2 of the RTCM standard. RTCM/RTK messages require at
least a 4800 baud data link.
Not all RTK positioning modes are supported when you use the
RTCM/RTK format. To ensure that you can use all the positioning
modes supported by the 5700 receiver, Trimble recommends that you
use the Compact Measurement Record format for all Trimble RTK
positioning applications.
C
Warning – Use caution when trying to mix RTK systems from different
manufacturers. Degraded performance nearly always results.
8.2.4
RTK Positioning Modes
The 5700 receiver supports two positioning modes to support a wide
variety of user applications. This section describes each mode,
outlines it requirements, and highlights the differences between the
modes.
Synchronized RTK (1 Hz)
Synchronized RTK is the most widely used technique to achieve
centimeter-level position estimates between a fixed reference station
and a roving receiver. Typically, the update rate for Synchronized RTK
is once per second (1 Hz). With Synchronized RTK, the rover receiver
must wait until the reference station measurements are received before
computing a baseline vector. The latency of the Synchronized position
fixes is dominated by the data link delay (see Figure 8.1, page 92).
Given a 4800 baud data link, the latency of the Synchronized RTK
fixes is up to 0.5 seconds. The solution latency could be reduced by
using a 9600 baud, or higher bandwidth data link.