Geode is not seeing satellites

28 Feb 2023

There are many reasons why it may appear that your Geode GNSS (GPS) receiver is not seeing satellites.

Note: The number of satellites shown by Geode Connect as Satellites in Fix are those satellites being used with the current correction source. This can be different from the number of GNSS satellites being tracked or received. In some situations, the number of satellites in fix will decrease when you change correction sources. For example, you might see 25 satellites with the Atlas correction source, but only 11 when you connect to an RTK network. This decrease would indicate that of the satellites in range of the Geode only 11 are available to the VRS network position or nearest base (MS solution) and the rover.

Following are some actions you could take to resolve specific problems which might decrease the number of satellites in fix.   

SBAS Satellites Not Being Used

  1. Disconnect and close (swipe away) your GPS/GIS data collection app
  2. From Geode Connect > Receiver Configuration > Advanced,  change the SBAS, e.g. from Auto to WAAS (or your available SBAS coverage).
  3. Select Save.
  4. Fully disconnect and close (swipe away) Geode Connect.
  5. Open your data collection app.

Potential App Conflict

Geode Connect may not see satellites when another app or the operating system is also trying to access the Geode (and/or your location) or vice-versa. After the initial setup and testing of the Geode,

New Receiver

To be able to use all of the available satellites and obtain the most reliable position, turn a new receiver on and leave it outside under an open sky for at least 25 minutes.

When a new receiver is first used, it needs to receive and download the almanac and ephemeris data from the GPS satellites. The almanac is broadcast from every satellite in 12.5 minutes segments and repeats every 25 minutes. The receiver may not see all of the available satellites or may see only a limited set of satellites until the download is complete.

For more information see the Geode Owner's Manual or the GNS3 User's Manual.

After Long Term Storage or Moving Long Distances

When the Geode has been stored for months or has been moved a long distance (such as across states or countries), it needs to download a new almanac and ephemeris. Set it outside under an open sky for 25 minutes. (See the explanation in the new receiver section above for more details.)

Initializing for Work Day

At the beginning of each work day, the Geode may need to be turned on and left outside under an open sky for at least a few minutes to obtain a 3D GNSS fix (indicated by the amber light flashing) and then a DGPS fix (indicated by the solid amber light).

Look for the solid amber light before connecting to a data collection app. During the work day, you may lose the DGPS fix (solid amber light) if an obstruction blocks the SBAS satellites which are at an angle above the southern horizon in the northern hemisphere (or at an angle above the northern sky in the southern hemisphere). The angle above the horizon decreases at higher latitudes and can result in more obstructions as the SBAS satellites will be lower in the sky. This and other possible causes to fix loss are shown and described in Best practices for better GPS accuracy in the field.

Enable NMEA Sentences

Specific NMEA sentences need to be enabled for the receiver to view certain satellites. In most instances, the default NMEA sentences are sufficient. The Geode Connect utility (or a terminal connection) can be used to enable these sentences. Some devices such as EM sensors and GPR (Ground Penetrating Radar) require only one or two sentences to be enabled (which may not include satellite information).

To verify and enable the GGA, GNS, GSA, and GSV sentences that contain satellite information, as well as other NMEA sentences, select Receiver Configuration (Settings) > NMEA Sentences. The defaults for all Geode models include GGA, GNS, GSA, GST, GSV, RMA, RRE, and VTG.

Specific Constellations

You can verify if a Geode unit is GPS only or Multi-GNSS by entering the serial number on our Check Product Status web page. An upgrade code can be purchased if needed. If you cannot see satellites from a specific GNSS constellation (such as Galileo or Beidou), please see Geode not showing Galileo or Beidou satellites. Using the Terminal in Geode Connect to submit commands such as $JGEO,ALL or $jwaasprn can help further determine what settings or subscriptions may be needed.

External Antenna not fully compatible

If you have the Geode GNS3M model with Multi-Frequency upgrade applied, our standard part number 26458 or 26319 single-frequency external antenna is not fully compatible. Instead, you need to obtain an alternative external mulit-frequency antenna. Consider the following possibility: 

https://www.digikey.com/en/products/detail/tallysman-wireless-inc/33-7972-07/9959589

We recommend attaching the external antenna before initially powering on the Geode.

Note: The web link above is provided as a reference and does not imply that Juniper Systems will provide full support for the use of any specific third-party device or software with a Juniper Systems product.

Soft Reset

The Geode Connect software utility can be used to Soft (Warm) Reset the Geode. From Menu > Receiver Configuration > Advanced > Receiver Reset > Reset Options, select Soft Reset. It may take a couple of minutes to reload and show data again.

Receiver Reset (to Factory Defaults)

Resetting the Geode to factory defaults is not recommended unless absolutely necessary. If the receiver is reset to factory defaults (a Hard Reset), a new almanac and ephemeris will need to be downloaded to the receiver. To obtain the most accurate position, the receiver must be turned on and left outside under an open sky for at least 25 minutes and sometimes longer. 

The Technical Details

When a complete reset is performed (which is the same as using $JRESET,BOOT command from the terminal) one of the items that gets reset is the JPOS value; this gets reset to "$JPOS,0,0". The JPOS value is the seed position the receiver uses to identify where on Earth the receiver is located so it can query the downloaded almanac and calculate a solution faster. Setting the receiver to "0,0" is sometimes referred to as "null island", meaning a location off the coast of Africa, or 0 degrees latitude and longitude. This may be why it takes longer for a receiver to track satellites and calculate an initial position.

The structure of the receiver and firmware doesn't allow loading and storing a manually entered $JPOS value until the receiver has determined an initial position.

The JPOS value is used to determine which SBAS satellite PRN values to look for. The position 0,0 will bring up EGNOS satellite PRN codes. The receiver firmware has an internal table of SBAS PRN IDs. As an example, if a value of $JPOS,42,-112 were entered (Juniper's northern Utah facility), then the firmware will use its internal SBAS table and identify the appropriate WAAS satellites.

The "JWAASPRN,AUTO command will only set the JWAASPRN search value to AUTO, and cannot be combined with other JWAASPRN commands to set specific PRNs in the same command string. Therefore, the default setting of Geode Connect should be left at AUTO for SBAS satellite selection, as this can be selected after a discrete constellation is selected.

Hardware Repair

If the Geode will not see satellites or provide a position fix after all of the above troubleshooting methods, then please submit the unit to a certified repair center. For our Utah factory repair center, please follow the instructions and fill out the Repair Order Form.

 

Reivew Pending: JF

Original article from Apr 2021