Commissioning troubleshooting
FarEarth will assist you during your in-orbit commissioning.
This page outlines the most common challenges of this phase and how to troubleshoot them.
FarEarth performs calibration and precision refinements during processing to compensate for specific anomalies. It is normal to see the anomalies listed below in your raw, uncalibrated data.
| Anomaly | Description |
|---|---|
| Vignetting | A gradual colour change across the image |
| Vertical streaking | Visible vertical striping across the entire image |
| Horizontal streaking | Visible horizontal striping across the entire image |
| Band alignment | Bands do not align and the image presents with a rainbow effect |
| Geolocation inaccuracy | Image is not geo-located and not projected |
| Radiometric inaccuracy | Image colouration anomalies |
Saturation
Pixel data is under- or over-saturated.
This can be caused by the TDI being too high or low. It can also be caused if the integration time is too high or low.
If you experience saturation problems, we recommend reviewing the following:
- TDI settings
- Integration time
When imaging, you want the average DN to be between 20% and 80% of the sensor's dynamic range. This leaves 20% at the top end for very bright objects, for example clouds. This also leaves 20% at the bottom of the range for very dark objects. You can confirm the nominal range with your sensor manufacturer.
Smeared imagery
Imagery appears smeared when the satellite is rotated by 180 degrees in the yaw axis.
This usually happens if TDI is used, and the sensor scan-direction is not changed on rotations.
If you experience smearing, check the following.
- Are you rotating the satellite by 180 degrees and using TDI?
- Is it necessary to change the scan direction on rotation?
Band offsets
There are offsets between the bands when the satellite is rotated by 180 degrees in the yaw axis.
Offsets occur if the satellite has been rotated, but the imager scan direction has not been changed.
If you experience band offsets, check the following.
- Are you rotating the satellite by 180 degrees?
- Is it necessary to change the scan direction on rotation?
Out-of-focus imagery or imagery with artefacts
Data is out of focus and/or have circular artefacts.
Satellite instruments are designed to operate under specific thermal conditions. When a camera does not operate within the proper temperature range, thermal expansion can negatively affect the alignment of optical components. This can cause focusing problems.
If you experience out-of-focus imagery, try the following.
- Attempt taking acquisitions at higher sensor and OFE temperatures to improve focus
- Confirm the nominal operating temperatures with the instrument manufacturer.
- Ensure that you control the temperature of your instrument.
- Heat your instruments to the correct temperature before acquisitions.
Horizontal streaking
Imagery has significant, repeated horizontal streaking.
This can be due to high TDI settings or invalid band start row settings.
If you experience horizontal streaking, review the following.
- TDI settings
- Band start rows
Suboptimal resolution in the along-track direction
If the line period does not match the required rate for the GSD, flight speed and altitude, the resolution in the direction of flight might be suboptimal.
If you experience suboptimal resolution in the along-track direction, review the following.
- Check that the line period is calculated to match the ground imaging speed, GSD and satellite altitude
Example: If an imager has a 5m GSD, the line rate should be calculated to match the GSD. If the ground imaging speed (not flight speed) is 7 km/s, then the line-rate should be approximately 714us.
FarEarth Level 0 Reports
FarEarth's Level 0 Quality Report, accessible in the platform, contains details that visualise the aspects discussed. This report is useful during your commissioning phase to track your satellite's behaviour.
See our blog about Level 0 Reports
Speak to us
The FarEarth team is here to guide you through this phase.