C-Nav Corrections Services
Following the email announcement in 2021 regarding the legacy corrections service retiring end of life October 2025 (replaced by the C-Nav LEO service with associated C-NavX1 GNSS receiver).
A copy of the bulletin for the End of Life announcement can be found here
The C-Nav Correction Service includes GLONASS and a GPS (GNSS) clock, as well as orbit correctors. It provides a fully independent suite of clock and orbit correction algorithms, and fully independent servers in geographically separated processing centers. Features also include a second independent global network of C-Nav dual frequency GPS/GLONASS reference stations equipped with Sapphire based technology, and simultaneously broadcasts from two independent satellite networks (Net-1 and Net-2).
C-NavC2 SF2 and SF3 use the latest realization of the International Terrestrial Reference Frame (ITRF). In other words, the C-Nav corrections are based upon ITRF20, and are adjusted on a daily basis (at UTC midnight) to account for minute shifts in velocity attributed to continental shifts on a global basis.
The C-Nav AuthCode System will automatically notify the original recipients of an AuthCode (C-Nav Correction License) that a license is nearing expiration. All email addresses associated with the original AuthCode, including all carbon copied (CC) recipients, will be notified.
The following tables outline the interval at which a notification email is sent.
| First Notification |
|---|
| >=days | Notify at days |
|---|---|
| 180 | 30 |
| 90 | 14 |
| 30 | 7 |
| 3 | 1 |
| Second Notification |
|---|
| >=days | Notify at days |
|---|---|
| 180 | 14 |
| 90 | 7 |
Examples:
- A 280 day AuthCode will get a notification when 30 days remain and another when 14 days remain.
- A 45 day AuthCode will get a single notification when 7 days remain.
- A 3 day AuthCode will get a single notification when 1 day remain.
DISCLAIMER: Although C-Nav strives to notify AuthCode recipients in a timely manner, delivery of email messages cannot be guaranteed due to factors beyond our control.
Unlike conventional Ground Based Augmentation Systems (GBAS) which determine highly temporal signal corrections, the C-Nav Corrections Service corrections are derived for satellite key parameters of orbit and clock. This is a more fundamental method of correction and as a result the accuracy degrades much more slowly with time. Excluding any sudden GNSS satellite anomalies, the last set of valid corrections will provide decimeter accuracies for up to and beyond 10 minutes. This is a setting made allowable to the user, which permits many accuracy tolerances dependent upon the application.
C-Nav Hardware
We’d recommend following the below checklists when installing your new receivers.
C-NavX1 installation checklist
C-NavX3 installation checklist
Any support queries can be addressed to cnavsupport@oceaneering.com
For the syncing of data between controller and receiver one of the connected receivers is assigned as the time device, if you are having an error make sure a time device is set at
C-NaviGator III:
menu>settings>general settings > Time Device Settings
C-Setup/C-Monitor/C-Setup :
Settings > Time Device Settings
If you have a suspected issue with your antenna, antenna cable run or receivers antenna output please refer to the troubleshoot guide linked below
CNAV-MAN-052.4 (C-Nav Troubleshooting Guide)
Please email cnavsupport@oceaneeering.com with your findings if you need further advice.
Plese see below guides for connecting using the C-NaviGator III or any of the PC control software
CNAV-MAN-037.2 (How to Connect a C-Nav3050 to C-Setup_C-Monitor_C-Scape)
CNAV-MAN-057.2 (How to Connect a C-Nav3050 to the C-NaviGator III)
Please email cnavsupport@oceaneeering.com with the part you’re stuck with for further advice.
A Snapshot is a file containing the current state of C-Monitor, C-Setup, or C-NaviGator, including pertinent information about each connected device, to a standard HTML file that can easily be read. This file can also be sent to C-Nav Support for troubleshooting purposes.
To save a Snapshot...
C-NaviGator III
- Insert a USB stick into an available USB port on the C-NaviGator.
- Press the Snapshot button on the right under the quality panel.
- Tap to highlight/select the USB stick, then press the Select Drive button.
- Wait several seconds for the file to be saved.
- To retrieve the Snapshot, remove the USB stick from the C-NaviGator and insert it in a PC.
- Navigate to the cnav/snapshot directory on the thumbdrive.
- The file can be viewed in a web browser or emailed to C-Nav Support for troubleshooting purposes.
C-NaviGator II
- Insert a USB stick into an available USB port on the C-NaviGator.
- Select Menu >> File >> Take Snapshot.
- Tap to highlight/select the USB stick, then press the Take Snapshot button.
- To retrieve the Snapshot file, remove the USB stick from the C-NaviGator and insert it in a PC.
- Navigate to the cnav/snapshot directory on the thumbdrive.
- The file can be viewed in a web browser or emailed to C-Nav Support for troubleshooting purposes.
C-Monitor/C-Setup
- In the Main Window, select File >> Save Snapshot.
- Locate a convenient folder to save the file.
- In the File name: text box, enter a descriptive name for the file.
- Click the Save button.
- The file can be viewed in a web browser or emailed to C-Nav Support for troubleshooting purposes.
After failure of a C-NaviGator III update, the user would next proceed to try a reload of a fresh image of the C-NaviGator III software, this is referred to as a rescue install.
C-NaviGator III Rescue Installer v10.0.1 (when clicking this link the file will automatically download)- 212 MB (Instructions)
Please email cnavsupport@oceaneering.com if you need any further advice.
For Antenna Phase Center Offset Information please see the Products Page.
To feed the POS MV we would recommend you use the either GGA or PNCTGGA (depending on POS version), this will give you the most accurate result. The feed can be setup as a C-Nav/NavCom receiver as shown below:
This will configure the POSMV to expect the proprietary C-Nav/NavCom message which will provided the best solution based on your hardware configuration.
Your C-Nav3050 needs to output NMEAPNCTGGA at 1hz interval to the POSMV, this message can be scheduled in the 'Output Control' menu.
The baud rate for the port you have the message scheduled on needs to match the POSMV baud rate, this can be checked on the 'Port Configuration' menu.
C-Tides® Software Package
This error occurs when the Area of Interest (AOI) is too large. Ideally, the AOI should be as small as possible around the desired location. Select a smaller bounding area and press Extract again.
There are three possible reasons for this error.
- The C-Tides Data package was not properly installed. Please read the section Install C-Tides Data(Page 12) of the C-Tides Quick Start Guide. Ensure that the C-Tides Data is installed into the same directory as the C-Tides® application.
- The Area of Interest is too large. Ideally, the AOI should be as small as possible around the desired location. Select a smaller bounding area.
- The MATLAB runtime has run out of system memory. Restart the C-Tides® application.
The ding sound indicates that the MATLAB Runtime has triggered an unexpected error that caused the C-Tides® software to stop execution. It is best to close the application and send the error to C-Nav™ Support for further troubleshooting. To close the application, press Ctrl + C in the busy dialog window. This will allow you to then close the main C-Tides® application window.All errors are logged to a diagnostic log file. The most recent diagnostic log file can be found at:C:\Users\{USERNAME}\AppData\Local\C-Nav\C-Tides\
This occurs when the C-Tides® Online application does not receive enough data to properly decode. Check the C-Nav3050® receiver output settings and ensure PVT1B is scheduled for at least 1Hz and that the baud rates match.
This occurs when the C-Nav3050® receiver has more messages scheduled on the serial port than the PVT1B. Check the C-Nav3050® receiver output settings and ensure that only PVT1B is scheduled for at least 1Hz.
The predicted tide values are derived from an independent solution that is detailed in the paper "FES 2004 Modern Insights". The values are based on a combination of MSS and tide gauge values around the world.
The predicted tide data are not available on land or in some areas near land. The easiest method to determine if the predicted tide data is available in your Area of Interest is to Plot Constituents. The last constituents graph—"ISLW: Approximately LAT w.r.t. MSL (m)"—will be non-white in areas with predicted tide data.
The predicted tide is a 14-year average of model data. The tidal height is based off of real values which are open to influence by local conditions such as weather, GPS errors, or offset errors.
In certain areas there may be significant differences between the EGM and MSS model results. The MSS model should give a better correlation to the predicted tide beyond 10 km from shore. If both models are significantly different to the predicted tide, check the COG offsets.
C-Tides is not a replacement for a tide gauge system. If the user is close enough to shore that tide gauges are available, then the user is too close to shore to be using C-Tides.
- To use the MSS model, the vessel must be 10 kilometers from the nearest land mass.
- To use the EGM model, the vessel must be in water with a depth of at least 10 meters. It is preferable to have a depth of at least 25 meters.
Using these models near-shore or in shallow water will affect the results due to land mass.
C-Tides is not able to generate an LAT or VORF solution.
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