General FAQs
General: Frequently Asked Questions
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General: Frequently Asked Questions
Last updated
If you need help, the preferred method of communication for support is through our ticketing system. To submit a support ticket, send an email to with the subject line as the title of your question and include your question in the body of the email.
Ellipsoid comes from the word "ellipse," which is simply a generalization of a circle. Ellipsoids are generalizations of spheres. The Earth is not a true sphere, it is an ellipsoid, as Earth is slightly wider than it is tall. Although other models exist, the ellipsoid is the best fit to Earth's true shape.
Like the ellipsoid, the geoid is a model of the Earth's surface. According to the University of Oklahoma, "the geoid is a representation of the surface of the earth that it would assume, if the sea covered the earth." This representation is also called the "surface of equal gravitational potential," and essentially represents the "mean sea level." The geoid model is not an exact representation of sea level surface. Dynamic effects, such as waves and tides, are excluded in the geoid model.
Unlike the geoid, the ellipsoid assumes that Earth's surface is smooth. Additionally, it assumes that the planet is completely homogeneous. If this were true, Earth could have no mountains or trenches. Further, the mean sea level would coincide with the ellipsoid surface. This is not true, however. Vertical distance exists between the geoid and the ellipsoid as a result of the geoid taking into account mountains and trenches as an Earth model. This difference is known as the "geoid height." The differences between the ellipsoid and geoid can be significant, as the ellipsoid is merely a baseline for measuring topographic elevation. It assumes that the Earth's surface is smooth, where the geoid does not.
If you need to reduce the size of a RINEX file, you could try slicing it into smaller chunks (about 4 hours) or decimating to a lower sample rate (5 seconds instead of 1 second) for upload. There is a free tool called (pronouced "tek") that can help you with either of those. Refer to the on UNAVCO's site for more information.
You can find a bit of information about using PPP to refine the coordinates logged for a static reference station in NovAtel's support document .
For more info on using PPP for processing the rover GNSS data, refer to NovAtel's An Introduction to GNSS, specifically .
There are two options to boresight your system detailed below: 1. You can send the system back to us for re-calibration. There is a flat charge for the calibration which includes aerial acquisition and data processing. Please fill out an on our site if you choose this option. 2. You can choose to fly the re-calibration acquisition mission yourself and upload the data to us for processing. If you select this option, please refer to the section in our User Manual for details of this process. Once the data is uploaded to our server through our page, there is a fee to process the data. When you’ve uploaded the data, send an email to support@phoenixlidar.com so that we are notified of your upload.