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California Fall Adjustment - May 10, 2021

It is once again time for a broadcast coordinate update in California.  The new broadcast coordinates will be published as of Monday morning May 10, 2021 at 5:00 AM ET and will ONLY effect California.

Why are we doing this adjustment?

California offers a unique set of challenges for RTK users.  A vast majority of the stations in California have significant positional velocities, which in short means they move.  On average the position of the stations in California moves between 30 and 50 mm-a-year, and in some areas even more.  The average shift over the entire network for this adjustment was approximately 18 mm.  

Without our semi-annual adjustment of station coordinates in California, you would quickly see measurable coordinate differences as you moved throughout the state.  As the velocities of the stations vary from location to location, this can cause issues not only as you cross the plate boundary, but also in the area of influence of the plates themselves.  In California's case, this means pretty much anywhere in the population centers of the state.

To get a better understanding of why we are doing this adjustment, please watch our latest SmartNet North American Adjustment Webinar - LINK.

What does this adjustment mean to me?

In very simple terms it means the broadcast position of the base is going to move approx. 20 mm.  This is a relative small change that you may or may not realize in the field, however as more time passes between adjustments, the larger the immediate impact would be.  By adjusting twice a year we mitigate the shift from adjustment to adjustment.

What reference frame and epoch are we moving to?

We will still be in the NAD83(NA2011)(MYCS2) reference frame to stay consistent with the NSRS and we are moving to a 2021.250 epoch.

How can I get back to my old coordinates?

With the introduction of Spider 7.1 in 2017, we introduced Multiple Reference Frame (MRF) Mountpoints.  These mountpoints allow you to access the Common or Last Coordinate Class that was published.  You can find more information on how to use these by watching the video below.

You can also perform your own local transformation, localization or calibration.  For more information about using this technique, please click here - LINK.

How do I see the current coordinates and superseded coordinates?

All current, common, last and superseded coordinates are available on the SmartNet User Portal.  You can find a station's information by using the "Site Information Search" tool, then you can see the current broadcast and processing coordinate, as well as find a button that will allow you to view all the coordinates available via an MRF mountpoint and superseded positions as well.

Once the new adjustment is published on May 10, we will also update the site database with the new NAD83(NA2011)(MYCS2) Epoch 2021.250 coordinates.

For more information on using the "Site Information Search" tool, we encourage you to watch this short video - LINK.

How do I get support to better understand what this adjustment means?

  1. Watch the most recent Adjustment webinar from November 2017 at http://adjustment17.smartnetna.com or our original Adjustment webinar from October 2012 at http://adjustment.smartnetna.com
  2. Utilize the MRF Mountpoints to access the Common or Last Coordinate Class that was published.  You can find more information on how to use these by watching the video above.
  3. If you are still unsure of what to do, please attempt to contact your local hardware/support representative first for information on how to use the MRF mountpoints or how to perform a transformation, calibration, localization, etc.
  4. If your local hardware/support representative is unable to answer your question, please search for the keyword "tools" on this Support Site
  5. If you are still unable to find an answer to your question, please email us at support@smartnetna.com or click "new" in the toolbar to submit a new support ticket
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