RTK Facet with Correction Data

GPS/GNSS Development Boards
1

I am trying very unsuccessfully to get correction data to work with the RTK Facet.

I can connect the Facet to Ucenter 22.07 and connect to an NTRIP Server from rtk2go server cornell_tech

Ucenter says that it is connected and receiving NTRIP data, but it does not appear that the data is going to the Facet or the Facet is not applying the correction data.

I’ve also tried SW Maps, RTKNavi, and Lefebure NTRIP Client version: 2017.07.27.

All software seems to have the same result, the RTK Facet is not utilizing or receiving the RTCM correction data.

The Server I am using is approximately 20 miles from my house and while I know that is outside of the best default range, I think it should still be a good test case for whether the Facet is setup correctly (but that may be an incorrect assumption?)

I am very confused, but I may have the right place to look.

I believe that my problem is an incorrectly setup Facet. It appears as if there are ways to customize the messages that the U-Blox receiver receives and sends. This would be accessed through the menu in UCenter for Messages view. I have seen references to modifying those settings, but have not been able to locate how to setup the receiver to allow it to do this or potentially find a correct configuration file to load.

So I guess the two questions I think might help me are

How do I verify that the RTK Facet is actually receiving the correction messages?

How would I verify that RTK is attempting to action the correction messages?

Any help would be greatly appreciated,

Jim

2

Here’s what I do and see, hoping this answers your questions.

I just fired this up and tried it; my reference station is 14 miles away and the Facet reports a RTK Fixed solution. While your station 20 miles away isn’t awesome, it should work just fine.

  1. I go outside and get a clear view of the sky.

  2. Start the Facet in Rover mode using the power/setup button.

  3. Start the app I’m going to use to forward the NTRIP data from the internet to the Facet.

  4. Use the app to connect to the Facet using Bluetooth. When I connect the device I’m going to use to send NTRIP to the Facet, the 4 hexadecimal numerals (part of the Bluetooth MAC) in the upper left corner change to the Bluetooth symbol.

  5. Use the app to setup and start the NTRIP data feed to the Facet. When the NTRIP data flows to the Facet via Bluetooth, the Bluetooth Icon alternates with a down arrow, indicating Bluetooth data flowing down to the Facet.

  6. When the ZED starts processing the NTRIP data to get an RTK solution, the target bullseye on the left center gets two concentric circles instead of one circle, and it starts to blink.

  7. When it gets an RTK Fix, the target bullseye stops blinking - it becomes solid with two concentric circles, and the HPA (Horizontal Positional Accuracy) number just to the right of the bullseye gets small, often it reads “.014” meters. But almost always a number that’s a few centimeters or less.

I didn’t need to use u-center or any other software to customize the ublox ZED messages. The out of the box Facet configurations work just fine. The WiFi AP configuration on the Facet also works very well if you need to change any of the Facet configuration, though when running a simple RTK Rover using NTRIP there’s not much, if anything, to configure on the Facet. The SparkFun folks have been good about having it work “out of the box” for this.

You might want to try:

  1. Resetting your Facet to factory defaults.

  2. Connect SWMaps on your android device to the Facet using Bluetooth.

  3. Make sure the Facet works well with SWMaps on an Android device in autonomous mode. That is, without NTRIP or RTK. Get good at using SWMaps in this mode first if you haven’t already. When I first used SWMaps, I found I didn’t understand the UI and SWMaps wasn’t always connecting to the Facet, it sometimes used the android device’s internal GPS if I wasn’t careful.

  4. Make sure your Facet is outside with a clear view of the sky. Trees and buildings are not a clear view. If you’re supplying NTRIP to the Facet via a USB cable from your PC, are you outside or inside at your desk? I tried doing this inside and it didn’t work for me. I tried doing this in one yard (comfy patio and table) under the trees and it didn’t work. I had to find a place with a mostly clear view; didn’t have to be perfectly clear though.

Hope that helps.

Tony.

PS I’m not a SWMaps expert, I don’t use it anymore as my surveying work required me to use professional (and expensive) survey software that forwards the NTRIP to the Facet.

3

Thank you very much!

This step through helped immensely. I am not sure why, but the original NTRIP server I was attempting to connect to wasn’t providing data correctly. With you assistance I could see that the Facet was getting data (With the Arrow behind the Bluetooth logo), but was not entering into the correct mode.

It also was important to do the test outside. Not sure why it can sit on my window sill for almost everything but this, however moving it outside was also neccessary.

I switched which station I was using, move it outside and it worked like a charm.

Thanks again,

Jim