You can find the documentation and download links on the official USGS VPV software page.
The request to "Download 838k txt" most likely refers to a specific sample data file used for the software provided by the U.S. Geological Survey (USGS) . USGS Velocity Profile Viewer (VPV) Data Download 838k txt
While the USGS file is the most direct match for that specific file size and description, "838k" also appears in other technical and data-heavy contexts: You can find the documentation and download links