How to Submit a Base Observation File to OPUS – LP360

Audience: Customers and GeoCue / LP360 Support
Applies to: Static GNSS base observations used for PPK Trajectory Processing, RTK bases or control evaluation

Purpose

This article explains how to correctly submit a base observation file to OPUS so it can be evaluated reliably. It is intended to:

Help customers submit usable OPUS solutions on the first attempt
Reduce common errors that lead to rejected base observations
Align submissions with how GeoCue evaluates OPUS results

This article covers submission only.

What You Need Before Submitting

Static GNSS observation file (RINEX preferred; vendor formats may work if OPUS supports them)
Antenna model (exact make and model used during the observation)
Antenna height (ARP height, in meters)
Email address to receive OPUS results

Important: Incorrect antenna height or antenna model is the most common cause of unusable OPUS results.

Step-by-Step: Submitting a Base File to OPUS

STEP 1 — Export the Base Observation File

Export the base as a static observation file from your GNSS receiver / processing software
RINEX is preferred; vendor formats are acceptable if OPUS supports them
Use the full observation duration (do not trim unless instructed)

Need to generate a RINEX file?
If your receiver produces proprietary formats (e.g., Topcon TPS), you may need to convert the raw data to RINEX before submitting to OPUS.

See vendor‑specific conversion guidance here:
Converting Raw GNSS Data to RINEX (Topcon Examples)

STEP 2 — Go to OPUS

Open the OPUS submission page:
https://www.ngs.noaa.gov/OPUS/

STEP 3 — Upload the Observation File

Select your observation file
Confirm the file uploads successfully (no format errors)

OPUS error: “Request Entity Too Large”
If OPUS rejects your submission due to file size, your RINEX file may need to be decimated.

OPUS internally decimates to 30‑second epochs
Removing unused constellations reduces file size

See step‑by‑step instructions here:
Troubleshooting: OPUS: Request Entity Too Large – Decimating a RINEX File

STEP 4 — Enter Antenna Information (Critical)

Antenna Model: Select the exact antenna used
Antenna Height:
- Enter the ARP height (vertical height to the antenna reference point)
- Units must be meters
- Do not convert slant height unless you know your workflow requires it

Common mistakes to avoid:

Wrong antenna model selected
Feet entered instead of meters
Slant height entered as vertical height

STEP 5 — Enter Email and Submit

Enter a valid email address
Submit the job
Wait for the OPUS results email

Recommended Observation Practices (Strongly Encouraged)

Observe the base for at least 1 hour (2+ hours preferred)

Need to trim or window a RINEX file?
If your base observation includes gaps, extra time before/after the survey, or does not align with the flight duration, trimming the RINEX file may help.

Learn How to Trim a RINEX File

Use a stable setup (tripod or fixed mount)
Avoid obstructions (trees/buildings) and reflective surfaces
Collect a second independent occupation when possible

Why this matters:
A single OPUS solution cannot confirm correctness. Repeat observations help verify stability and reduce the risk of setup/environmental bias.

After Submission: What Happens Next

OPUS processes the observation and emails a report
The report includes quality indicators (e.g., RMS, peak-to-peak, CORS used)
Evaluate the result using OPUS metrics and repeatability
Import into Survey Manager to create a Survey Nail for use in your Trajectory Processing.

Troubleshooting

OPUS fails to process: The file format may be unsupported, or the file may be corrupted
Results look poor: Re-check antenna height/model, observation duration, and site environment
Base rejected: Often due to metadata errors or lack of repeatability (only one occupation)

Base observation quality checks
If OPUS results are inconsistent or fail quality checks, review the base observation file itself:

RINEX header (antenna, interval, constellations)
Observation duration and overlap
Constellation support and sampling rate

Troubleshooting: Base Station Observation Files

Summary

Submit a clean static base file (RINEX preferred)
Enter correct antenna model and ARP height (meters)
Prefer longer observations and repeat occupations
OPUS submission quality directly affects RTK reliability

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