Bad Elf Flex: Collecting RINEX Data and Post-Processing with OPUS

Bad Elf Flex: Collecting RINEX Data and Post-Processing with OPUS

Bad Elf Flex: Collecting RINEX Data and Post-Processing with OPUS

Overview

The Bad Elf Flex allows users to collect raw GNSS observation data in RINEX format for post-processing using the Online Positioning User Service (OPUS) provided by the National Geodetic Survey (NGS). OPUS enables users to obtain highly accurate geospatial coordinates by processing RINEX data against reference stations. This workflow is helpful if no RTK corrections are available to achieve similar results.

This guide walks you through:

  1. Enabling RINEX Logging on the Bad Elf Flex
  2. Collecting GNSS Data in the Field
  3. Downloading RINEX Files
  4. Submitting RINEX Data to OPUS
  5. Interpreting OPUS Results

Step 1: Enable RINEX Logging on Bad Elf Flex

  1. The Bad Elf Flex is capable of collecting raw logs with or without a mobile device.
    1. Bad Elf Flex App: Standalone Data Collection
    2. Bad Elf Flex Logging Features
Notes
A Bad Elf Flex Extreme is required to collect RAW logs. Extreme Mode is activated either by purchasing the permanent unlock or through the use of a Bad Elf Flex Token.

Step 2: Collect GNSS Data in the Field

  1. Place your Bad Elf Flex on a tripod or fixed survey point.
  2. Begin collecting data by navigating to a. GCP on the Bad Elf Flex or b. Raw Logging in the Bad Elf Flex App.



  3. Allow the device to collect GNSS data for at least 15 minutes (30 minutes is highly recommended), though longer sessions (2 hours+) improve accuracy.
  4. When finished, stop logging in the Bad Elf Flex App.

Step 3: Download RINEX Files

  1. In the Bad Elf Flex App or on the Bad Elf Flex receiver, navigate to Logs.
    1. Bad Elf Flex App: Log View and Download
    2. Bad Elf Flex: Logging Features
  2. Select the recorded log session and choose Export as RINEX.
  3. Export the file locally on a USB drive via the Flex On-The-Go adapter or share it to your app of choice via the Bad Elf Flex App for easy access.

Step 4: Submit RINEX Data to OPUS

  1. Open a web browser and go to the OPUS submission page:
    1. OPUS Tool
  2. Click Choose File and select your RINEX file.
    1. The file format is .25o or similar.
  3. Enter your email address to receive the processed results.
  4. Select the appropriate antenna type:
    1. If using the internal antenna, select "NONE".
    2. If using an external antenna, enter its specifications.
  5. Enter the antenna height.
    1. Add 0.23m to account for the antenna phase center offset from the pole mount at the bottom of the receiver.
    2. Example: If using a 2 meter survey pole, enter 2.23 meters.
  6. Click Upload to Rapid-Static for observations less than two hours, and Upload to Static for observations lasting two hours or more.
  7. Wait for an email containing your corrected coordinates.
Notes
Processing time typically takes 10–30 minutes.

Step 5: Interpret OPUS Results

The OPUS report provides:

  1. Processing parameters and RINEX quality metrics.
    1. OVERALL RMS provides the accuracy of the corrected solution in meters.
  2. Corrected ECEF and latitude/longitude coordinates in the NAD83(2011) and ITRF2014 reference frames.
    1. Accuracy for each coordinate is given in meters.
    2. ITRF2014 is equivalent to the WGS84(G2139) realization.
  3. Elevation data (ellipsoidal and orthometric (NAVD88) heights).
  4. UTM and State Plane coordinates with scale factors.
  5. Base stations used for corrections.
  6. Nearest control point.

Use the corrected coordinates for high-accuracy GIS mapping, surveying, and engineering applications.


For any issues or further assistance, contact Bad Elf Support at support@bad-elf.com.




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