GNSS Decoding

GNSS Decoding

Vesper and Nanotag positions work by snapshot GNSS: instead of running a power-hungry GNSS receiver to a live fix, the tag stores short raw RF snapshots (G.BIN). Back at the computer, the GNSS decoder plugin post-processes those snapshots into latitude/longitude fixes.

Requirements

• The GNSS decoder plugin must be installed — see Software Updates and Plugins. Without it, all other decoding still works; only GNSS decode is unavailable.
• An internet connection is used to fetch satellite aiding data (ephemeris) for the recording period.

Decoding snapshots

Usually you don't need to do anything: with Auto Decode on, DAT folders produced during import are decoded automatically (Recordings).

To decode manually:

1. In Recordings, browse to the DAT folder of a recording session.
2. Press Manual GPS Parser.
3. A GNSS job appears in the Decoding Progress panel showing "Decoding snapshot X of Y…", a live console tail and elapsed time.

Results

The decoder writes its output files to the recording's decode folder and reports each successful fix (time, latitude, longitude, altitude, horizontal accuracy, satellites used).

A full log of every job is kept in logs/gnss/ under the app data folder (%LOCALAPPDATA%\VesperApp on Windows, ~/Library/Application Support/VesperApp on macOS, ~/.local/share/VesperApp on Linux) — the Open Log button on the job panel takes you straight to it. Include this file when reporting decode problems.

Tips for good fixes

• Snapshots recorded with a clear view of the sky decode best; heavy canopy or indoor captures may yield no fix for some snapshots — that is expected, not an error.
• Decode runs entirely on your computer; large snapshot sets take time and benefit from letting jobs run in the background.
• If every snapshot fails to decode, verify the plugin is installed and current, then check the job log for details. See Troubleshooting and FAQ.