This Page - GS20 sub-metre surveying

GIS data collection on a PDA- Leica GS5 and GS5+

The new DGPS- GIS data collection system from Leica

	This shows the belt arrangement for the RTB "WORCS" set, for batteries, beacon receiver,and bluetooth transmitter. The handheld unit has no physical connection to the belt, so can be used up to 10 metres away from the body. For a full diagram of this system, see the RTB diagram page.
There are three real time systems available to GS20 users for DGPS, to an accuracy of 0.4 metres. See further below for post-processed options. 1. DGPS using beacons such as the Australian AMSA (covers much of Australia's coastline and 300km inland), or the US Coast Guard (in the USA). This is called the RTB set. See description above. 2. DGPS using satellite differential signal from Omnistar. This is called the RTS set. This has world-wide coverage, including Australia, PNG, Indonesia, SE Asia, China, India etc. Use in the remotest areas, no base station to set up. Perfect for preliminary surveys. This is called the RTS set. 3. DGPS using a local RTCM transmitter. Many mining companies and other utilities already have RTK GPS sytems that transmit a DGPS signal. The GS20 will fit perfectly in these situations for quick geological, or civil engineering pickup.
Post-processing data in a computer is also a DGPS option. Accuracy will depend on method. Link for more detail. 1. You can collect data in Leica or Rinex format for post-processing by computer, with base station data. This is normally for code L1 data, to around 0.3 metres. Occupation times on each point, is 2-5 minutes, to ensure most productive data, as there is no way of knowing position accuracy until after process. Base station data can be purchased from a third party supplier (usually government or university facilities), or using a second Leica unit to log corrections at a known point. 2. Collected data can include phase data for cm level accuracy. Elevations of less than 50mm will be normal, but the occupation time of 20-30 minutes will be mandatory for each point. Base station data can be purchased from a third party supplier (usually government or university facilities), or using a second Leica unit to log corrections at a known point. This method requires an additional software module for GIS Data Pro.

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