Trimble Outdoors 5700 - Manual (Page 109)

5700 GPS Receiver User Guide 9 3
Real-Time Kinematic (RTK) Surveying 8
Appl
icatio
ns
8.2.3
Data Link
The data link transfers the reference receiver’s carrier phase and code
measurements, and the location and description of the reference
station, to the rover.
The TRIMMARK 3 reference radio modem, with the 5700 receiver’s
internal receive-only radio, is designed for 5700 receiver RTK
operation. TRIMTALK 450 radio modems are also customized for
RTK applications. You can also use third-party radio modems, cellular
phones, or satellite communication links to transmit reference station
data to one or more rover sites.
Factors to consider when choosing a data link include:
• Throughput capacity
• Range
• Duty cycle
• Error checking and correction
• Power consumption
The data link must support at least 2400 baud throughput. However, a
throughput of 9600 baud is preferable.
Correction message formats
In addition to selecting a data link, you need to decide in which format
messages will be transmitted over the data link. The 5700 receiver
supports two standards for RTK positioning: the Compact
Measurement Record (CMR) format and the RTCM/RTK message
format.
The Compact Measurement Record (CMR) format was designed by
Trimble and is supported by all Trimble RTK products. CMR
messages require at least a 2400 baud data link.