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The RINEX files are uploaded directly to the post-processing service's web page. The service is available for logged in users with a post-processing subscription.
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Here you can read about the requirements on the RINEX file to be processed, as well as information on how antenna types and antenna heights are handled.
Requirements on the input data
Your uploaded RINEX file will be checked when you order a new post-processing job, to make sure that the file meets the formal requirements and that all necessary information is included.
File format and header
The observation file to be calculated must be in RINEX format:
- RINEX 2 observation files always have the file extension *.yyo, e.g. "point.21o" for a measurement carried out in 2021.
- Observation files in RINEX 3 format or later always have the file extension *.rnx, e.g. "point.rnx".
The following information must be available in the RINEX file:
- Approximate coordinates of the measured point
- Antenna height
- Antenna and receiver type
The post-processing service reads the information from the header of the RINEX file. Since RINEX files are in ASCII format, you can check and edit the data in the file header using any text editor, e.g. Notepad. Note that the values in the file header are position bound.
Observation types and observation time
The RINEX file must contain static dual-frequency GPS observations. If you want to use Glonass and Galileo for processing, the file must also contain dual-frequency observations of them. When ordering the calculation, you choose which satellite systems (in addition to GPS) are to be used.
|
GNSS
|
Frequencies
|
|---|---|
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GPS
|
L1, L2
|
|
Glonass
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L1, L2
|
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Galileo
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L1 (E1), L5 (E5a)
|
The processing utilises data from satellites down to 3 degrees elevation. The elevation mask in your GNSS receiver should therefore be 3 degrees or less.
The calculation is done with 30 second observation intervals, so the submitted file should have the same observation interval. If data is logged at more frequent intervals – e.g. 1, 5, 10 or 15 second intervals – the file will be reduced to 30 second intervals. It is not suitable to use 20 second logging intervals because the file will then be reduced to 60 second intervals for processing.
To get a reliable result with centimetre accuracy, it is recommended that you observe for two hours or more. The processing cannot be started if the measurement time is shorter than 30 minutes. If the observation time is between 30 minutes and two hours, you will receive a warning that the result may be uncertain.
Antenna height in the RINEX file
The post-processing service assumes that the antenna height specified in the header of the RINEX file is the vertical height to the antenna reference point, ARP.
The ARP (antenna reference point) is usually the bottom of the antenna, but you should check what applies to the type of antenna you are using. You should be able to find the information on the antenna or in the equipment's user manual. Information on ARP, as well as information on how to correct from measured slant antenna height to vertical antenna height to ARP, is also available at the following websites:
- IGS's file with antenna dimensions (new window).
- NGS's antenna calibration page (new window). Select the antenna manufacturer and then the antenna type you want to view. Then click on Drawing to see the dimensions of the antenna.
If antenna height is missing in your RINEX file, then the processing will be performed with antenna height 0.000 m, and you will get a warning in the result file.
Antenna types supported by the post-processing service
The post-processing service has a large catalogue of different antenna models. In order for the correct antenna model to be used in the processing, you must specify the correct antenna type in the header of the RINEX file. The antenna type must consist of antenna and radome designations.
The RINEX file control will give a warning if antenna type information is missing in the file, if the antenna model lacks correction values for any of the observed satellite systems, or if the antenna type is not recognised by the service.
When you are logged in to the service, you can see which antenna types that are supported. If needed, more antennas can be added.
If your antenna type is not listed, you can look at the photos on NGS's antenna calibration page (new window) and identify your antenna there. The Geo ++ antenna calibration page (new window) can also be an option to identify your antenna. The websites use standardised designations, so-called IGS designations, for the different antenna types. The post-processing service uses the same standardised names. If you cannot identify your antenna on any of these websites, your instrument supplier can help you. Ask for the IGS designation of the antenna.
Then check if the standardised designation of the antenna type is in the list of antennas supported in the service. In that case, you can either
- change the antenna type designation in the header of the RINEX file, to the standardised designation, or
- contact Swepos control centre and tell them which antenna type is in the header of the RINEX file and which antenna model should be used for it, and we will add a translation between the designation in your RINEX file and the antenna model to be used in the post-processing service.
If your antenna type – with the correct standardised designation – is not included among the antenna types supported by the post-processing service, contact Swepos control centre.
The antenna type is often automatically written to the RINEX file when it is created. The antenna designation is always written with 16 characters starting at column 21 on the line marked with the comment "ANT # / TYPE". If the designation is shorter, it must be filled out with blanks. If the antenna has a radome mounted, write the 4 characters of the radome designation beginning at column 37 on the same line. If no radome was used, the text "NONE" or 4 blanks must be entered. If the radome designation consists of only blanks, the post-processing service will add the radome designation "NONE".
About antenna models
A prerequisite for high-quality height determination is that the so-called electrical centre of the antenna is described in a sufficient way. An antenna model is a mathematical description of how this electrical centre varies relative to a physical point (ARP) on the antenna, depending on the incoming signal. The antenna models are needed to describe the specific variation in different antenna types.
An antenna model can contain values – phase centre variations or phase centre corrections – for one or more satellite systems, depending, among other things, on the time at which the description of the antenna's electrical characteristics was made.
Sometimes these correction values have been copied for one satellite system to another, in case values have been missing in the antenna model. For example, the values for GPS may have been copied, so that they also apply to Glonass or Galileo. This is not done in the post-processing service, but only the satellite systems that have correction values in the antenna model are used in the calculation. That means, if you use an antenna whose antenna model contains corrections for GPS and Glonass, but not for Galileo, then Galileo will not be used in the calculation, even if your RINEX file contains Galileo observations.
If the antenna model lacks correction values for any of the satellite systems supported by the post-processing service, you will receive a warning in the initial check of the RINEX file.
Receiver types supported by the post-processing service
The post-processing service supports the vast majority of receiver types, but needs information about which receiver type was used during the measurement. The receiver type is found on the line in the RINEX file with the comment "REC # / TYPE / VERS".
The RINEX file check will give a warning if receiver type information is missing.
If the processing fails
If an error occurs, and the processing fails, you will receive an error message via email. The Swepos control centre will trouble-shoot the processing job and get back to you as soon as possible. Contact Swepos control centre if you have questions.
Please do not resubmit the same RINEX file for processing until you are notified of the trouble-shooting.