RTK Facet L-Band Not Receiving Corrections

GPS/GNSS Development Boards
1

I have an RTK Facet L-Band, product GPS-20000, that works great with one exception: I am not receiving satellite corrections.

Current state:

I can power on the Facet, it starts reading satellites as expected. After a few minutes it gets me to ~ 1 meter accuracy w/ 20-30 satellites. That all seems to work well. However, I never get any better accuracy - nor do the images on the Facet’s display indicate I am getting corrections (ie the 3 little bars on the satellite image).

Error:

Using Tera Term, I pull up the Main Menu, and then select System Status, which yields “L-Band: Online - Keys Good / Corrections Received Failed / Eb/N0[dB] <>9 is good): 0.00”.

…photo of this output is attached.

Historically what I’ve done:

  1. Placed Facet in CONFIG mode (setup button presses until Config displays).

  2. The Facet’s ESP32 boots into AP mode, and I successfully connect to WiFi

  3. I successfully launched the webpage (192.168.4.1) and set the Home Wifi & pwd. I left the 3rd field blank under the PointPerfect section of the webpage.

  4. I save and reboot.

  5. The Facet successfully downloaded the keys, and I have 40 days remaining.

…everything seems to work as expected regarding key management.

Additional Test:

  1. Via BT I connection my Android phone to the L-Band Facet.

  2. Using SW Maps, i get a reading and everything works as expected at reduced accuracy.

  3. I have an RTK Facet (non-L-Band version), product GPS-19984, so I thought I would using my account to send NTRIP corrections (as received from the cellphone) and that works perfectly…the system gets me to ~20mm accuracy. This tells me the L-Band Facet is capable of getting to RTK Fix, if it can just receive the corrections.

Current configuration:

Taken from the SFE_Facet_LBand_Settings_0.txt, the following configuration versions:

rtkIdentifier=34

rtkFirmwareVersion=v2.2-Jun 8 2022

zedFirmwareVersion=HPG 1.32

Conclusion:

The Facet L-Band is working at reduced accuracy, home WiFi is set, the keys are successfully downloading…BUT I never actually receive any corrections. I have left it on for over an hour, and still reduced accuracy.

I welcome any thoughts. I’m guessing I just need to return for a different one?

Thanks in advance.

facetLBandSmall.png
facetLBandSmall.png720×540 514 KB

2

Great issue write up. Thank you!

After a few minutes it gets me to ~ 1 meter accuracy w/ 20-30 satellites.

20-30 SIV is good, but I regularly see better than 0.25m accuracy, sometimes 0.15m. Let me know if you are still at a 1m accuracy under normal (no L-Band, no RTCM) operating conditions. How does this unit compare with your non-L-Band Facet? They should be very similar.

“L-Band: Online - Keys Good / Corrections Received Failed / Eb/N0[dB] <>9 is good): 0.00”.

Ok, looks like you’re unit has connected to u-blox for credentials (good!) but no reception. L-Band is far weaker than GNSS signals. Was the antenna outside with a clear view of the sky when you took the terminal output photo? I know it’s tricky to debug a thing that’s supposed to be outside that also needs a serial terminal connection.

I have an RTK Facet (non-L-Band version), product GPS-19984, so I thought I would using my account to send NTRIP corrections (as received from the cellphone) and that works perfectly…the system gets me to ~20mm accuracy. This tells me the L-Band Facet is capable of getting to RTK Fix, if it can just receive the corrections.

You’re doing all the right things! The ZED has proper firmware. The antenna and ZED are functioning. You’ve got your keys. Please take the unit for a walk. Assuming you are in the USA, get a clear view of the southern sky (where the Inmarsat sat sits). You should see the SIV icon turn to 3-pronged within 60 seconds. The 3-prong indicates successful reception and decoding of an L-Band packet. RTK float/fix may take longer, but the packets should start arriving very quickly.

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