Post processing STA Explorer HA data

One of the key differences between the STA Explorer HA and the standard STA Explorer is the ability to post process raw GNSS observations to achieve much higher positional accuracy. While the field workflow remains simple, the processing workflow introduces a number of additional steps that may be unfamiliar to users who have not previously worked with GNSS post processing.

The overall concept is relatively straightforward. During operation, the STA Explorer HA records raw GNSS observations alongside the standard operational tracking data. After field collection, these observations are combined with data from a nearby GNSS base station to calculate corrected positions through a PPK workflow.

Worked example

The first step is obtaining suitable base station data covering the period of field work. In Australia, this is commonly sourced through the AusCORS network, where observation and navigation files can be downloaded from publicly available government infrastructure. Typically, the required downloads include Observation files and Navigation files.

Depending on the source, observation data may be supplied in compressed CRX format rather than standard RINEX format. In these situations, the files must first be converted before processing can occur. A commonly used utility for this conversion is CRX2RNX Utility. There are also other GNSS utilities and processing packages capable of performing this conversion. Users who are unfamiliar with GNSS data formats may wish to contact support for assistance with this stage of the workflow.

Once the base station files are prepared, the next step is processing the STA Explorer HA raw GNSS data. The STA device records raw observations in UBX format, which are provided separately via file share.

Several software packages can perform the post processing step. RTKLIB is a powerful package, however for single file processing, Emlid Studio is often one of the simplest starting points due to its relatively user-friendly workflow and visual interface.

The general workflow involves:

• Loading the STA Explorer HA UBX file as the rover dataset
• Loading the converted RINEX observation file as the base station dataset
• Loading the navigation file
• Configuring processing settings
• Running the PPK solution

Emlid have published a more comprehensive guide to using Emlid Studio, which you can view here.

After processing, the software generates corrected coordinate outputs, commonly as a POS file or similar coordinate dataset.

One important detail is that the logging frequency of the STA Explorer HA and the base station may not perfectly align. In many workflows, interpolation or resampling is performed automatically by the processing software to align observations during solution generation.

Once a corrected position file has been produced, the next step is converting those corrected coordinates into a more usable tabular format such as CSV. From there, the corrected positional data can be aligned back against the original STA operational attribute data, allowing the improved coordinates to inherit the planting event information, timestamps, selectors, operational metadata, and other associated attributes recorded during field collection. This final alignment step is important because the GNSS processing software typically only outputs corrected positioning information rather than the full operational dataset used within the STA platform.

At present, these workflows are performed externally to the STA Portal. Post processed coordinates are not automatically written back into live operational layers unless future automated HA processing workflows are introduced into the subscription platform.

While the workflow may initially appear technical, much of it becomes routine after a small number of processing runs. Organisations already familiar with GNSS or survey-style workflows will likely find the process relatively familiar, while users approaching PPK for the first time may benefit from some initial guidance and support.