Trying to connect Base Postcard to Rover Postcard using local wifi

GPS/GNSS
1

Hi,

I’ve got a specific application that I’m trying to setup on my two Postcards that is giving me issues. Here are the details:

I’ve got one Postcard as a base and one as a Rover.

I want to send the base corrections to the rover using a local (not connected to the internet) wifi.

The wifi system I want to use is actually the wifi that comes with the UBLOX C099-F9P. I’ve used it before to pass small amounts of data from a phone to my computer so I know that it will work. Note that I am NOT trying to use any of the data that the C099-F9P produces - just using its WIFI network.

I’d like the base station to have a static IP address if at all possible.

How do I configure the base and rover to do this? I’ve tried setting the base to be in base with NTRIP server enabled and put it in base caster mode but I can’t get the rover to connect with the base.

Can someone advise as to how I setup my Postcards to do this? FYI - I am running RTK Everywhere v3.4 and V2.01 for the LG290P

2

Looks like I solved the issue.

I used the Web Config to look at the settings and noticed that the NTRIP server had a typo with the wrong IP address. Pretty sure that it looked ok in the serial terminal.

changed that and got RTK fix right away.

I am seeing a bit of a hesitation on my secondary app that reads the data coming in - it’s about every 7secs or so that the data hesitates for a 1/2sec or so. Not sure if I’ve got a bad setting (turn off NTRIP?)or if there is a Bluetooth capacity issue. My rover is set to 10Hz. Hopefully I can resolve it as other than that it’s working well.

also wondering if there are better instructions on how to use the base assist? I’d like to be able to store a few base’s and then put them back in when needed - not really sure how to use this function and there is nothing in the documentation that I can see?

3

Nice! As for the data hiccups I would take a look at disabling any unneeded messages. Are you missing any data or is it just stuttering but complete?

There’s a bit in their guide that might help (they also have forums that might help if no one chimes in here)

4

Thanks Russell. I’ll check that out. Can you advise on the exact settings (ie BASECASTER mode, etc) I should use to do what I am looking to do? I have a feeling that part of my stuttering is possibly a wrong setting.

5

I was a bit confused, but I think I have a handle on it now. For your setup, the key distinction is that you don’t want the Postcard acting as an NTRIP Server in the usual “send corrections to an external/Internet caster” sense. You want the Base Postcard itself to act as the local NTRIP caster, with the Rover connecting directly to it over the C099-F9P’s Wi-Fi network.

BaseCaster gives you the local caster functionality you need: Base Menu

Base mode + NTRIP Caster + TCP 2101

So the basic configuration would be BaseCaster on the Base and NTRIP Client on the Rover.

Base Postcard — hosting the caster

  • Wi-Fi: Join the C099-F9P’s Wi-Fi network as a station.

  • System Mode: BaseCaster

  • Base type: Surveyed or Fixed, depending on whether you’re using survey-in or a known fixed position.

  • NTRIP Caster: Enabled

  • TCP port: 2101

  • Configure the mount point, username, and password for the local caster.

  • NTRIP Server: Disabled. That is used to push corrections to an external caster such as RTK2Go and isn’t needed for this setup.

The important distinction is that the NTRIP Server pushes RTCM to a caster, whereas the NTRIP Caster accepts connections from NTRIP clients.

Rover Postcard

  • Wi-Fi: Join the same C099-F9P network.

  • System Mode: Rover

  • NTRIP Client: Enabled

  • Host/address: The Base Postcard’s IP address

  • Port: 2101

  • Mount point: The mount point configured on the Base

  • Username/password: Match the Base’s caster settings.

The resulting data path should be:

LG290P Base
     │
     │ RTCM
     ▼
Base Postcard
  NTRIP Caster
  TCP :2101
     │
     │ Local Wi-Fi
     ▼
C099-F9P Wi-Fi AP
     │
     ▼
Rover Postcard
  NTRIP Client
     │
     ▼
LG290P Rover

Static IP

We don’t currently have much documentation on configuring a static IP on the Postcard, so I’d treat that as a second step. Get everything working using the IP address assigned to the Base by DHCP. Once that’s working, you can look at making the address predictable (either via F9P DHCP reservation or if the postcard settings allow setting static IP…unsure if either of those are supported, check their menus)

Our firmware also supports mDNS, so rtk.local may be usable instead of an IP address when both devices are on the same network.

The other relevant documentation is here:

TCP/UDP Menu

WiFi Menu

6

Thanks Russell. This is great! One wrinkle that is specific to the C099-F9P is that the wifi has a different subnet than the Postcard. The Postcard want 192.168.4.1 whereas the C099-F9P’s subnet is 192.168.0.X. So I tried forcing the Postcard to the same subnet: 192.168.0.x and it seemed to work. It also seems like it stays on a fixed IP address through power cycles.

I’ll review my settings and try it again and see if there is an impact on the stuttering

7

I tried this configuration and it worked well. Couple of notes:

  • as mentioned above, I fixed both of the IP addresses on the Rover and the Base to match the WIFI subnet. No issues that I could tell with this
  • on the Rover, under WIFI, I have it set to WIFI whereas on the Base I have it set to AP
  • Also, in regards to stuttering, I noted that I had it on Bluetooth:Dual. I changed it to Classic. Stuttering seems better now.