SURVEY

Subject
 Trimble Survey Controller Software: Naming Conventions in a GNSS Networking Survey
Product(s)
 Trimble Survey Controller™ software, Trimble® GPSNet™ reference station software, VRS™ network
Question
 1. Where do RTCM… and PRS… names come from?

2. What does “New Base Detected” mean?

Answer
 1.

RTCM names are created in RTCM v3.x reference station messages by the network and are then transferred to the Trimble Survey Controller software and the rover receiver.

PRS names are created by the Trimble Survey Controller software when storing vectors if the physical base station name is missing from the network messages.

2.

RTCM names are different when the network is set to increment the IDs for each RTCM generator in the VRS network software on each new rover connection. Every virtual reference station that is created has an incremented ID.

When the VRS network starts sending out RTCM messages, RTK starts at the rover. If the network immediately changes something in these RTCM messages (for example an ID, or if the ID starts as null and then becomes a value), the rover displays the message New Base Detected. Even though the rover position has not changed, the rover receiver flags that it has a new base and the Trimble Survey Controller software switches bases.

The software also switches bases when the network moves from networking (Trimble GPSNet in VRS mode) to raw mode (single base mode). A message, Trimble GPSNet in RAW-Mode, appears. At this stage, a point is written to the Trimble Survey Controller job even if you are connected to a VRS network and are storing positions. 

The network provider can set the network to switch to raw mode when the user is within a configurable distance of the closest physical reference station; however, there are also other reasons why the network would switch to raw mode. These include a network becoming unsolved, a station going down, and the user moving outside the network. A new base station is also reported after the receiver has been reset for any reason.

Note: When the network switches to raw mode, the Trimble Survey Controller software switches from storing positions to storing vectors. It also changes the stored points from Wide Area Fixed to Fixed observation class.
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