RTK gps

[jesse brockmann]

Hello,

   Anyone use rtk gps yet?   Saw this video 

https://twitter.com/SmallpixelCar/status/1259242473177534464?s=09

today and it is really motivating me to start using mine soon.   I promise to do a write-up on it when I do.   

Regards

JesseJay

[Jeff Webb]

I've built a rover using Sparkfun SparkFun GPS-RTK2 Board - ZED-F9P (Qwiic)
GPS-15136

I'm not the greatest at this but I'm learning and progressing pretty quickly. Its been pretty exciting getting it running. I'm using an older PCDUINO that I had laying around since I'm most comfortable in the linux environment. Connecting the motors and and a couple of sensors is complete. Network connectivity and wiring is also complete. I've written basic scripts for movement but nothing is autonomous yet. Logging and viewing the GPS status can be done on linux using the RTKLIB, rtklibexplorer or piped to internet port using gpsd and socat to be consumed by ucenter on windows. Ntrip connectivity comes from  UNAVCO and injected using str2str. 

I'm currently trying to write the code that would move to waypoints automatically. Next would be activating the switch on the weed sprayer.

The end goals are

1.) Learn and have fun

2.) Very basic topography of my property for landscaping/construction purposes. Possibly something I feed into archicad.

The dream big plan (most likely not possible with my skill set)

1.) Selectively spray weeds on a 200 yard x 25 yard strip of asphalt. Currently a large spray tractor does the work. The spraying in bulk and indiscriminate. Spraying only the weeds with a robot and not the asphalt would reduce human exposure to chemicals, lower costs of materials and make the process a lot more eco friendly.

 I love getting guidance and if anything I've done can help someone else, let me know.

Jeff

[Jon Russell]

Hi,

Can anyone give me some help with setting up RTK ?

I bought two ZED-F9P boards from SparkFun ages ago and every time I try to get them working, I always fail.

Lets just talk about the base station to start with ... 

IIUIC I need to know my accurate fixed position for the base station, before it will switch to "TIME" RTK mode ?

Once in TIME mode, it should output RTCM messages to UART2, which I can send to the rover RTK board on it's UART 2.

I can set the position of the base unit either manually, or run "Survey-In" ?

I cant ever get Survey-In to complete ?

I reset the base board to factory defaults. I run Survey-In using uCenter.

I tried the default std dev settings in uCenter, but that failed, so I tried something it should be able to achieve. I tried 300 seconds and 5m.

IIUIC this means it will survey for 300  second, and must achieve a std dev of less than 5m, and if so, then switch to TIME mode ?

It never completes ?

It stays in 3D mode.

Is my std dev not less than 5m ? Is it related to one of the 3D Acc or DOP figures ? Can I get a text readout of it anywhere ?

So, questions ... 

• Have I misunderstood Survey In ? Why doesn't it ever complete ? Do I need to leave it running for 24 hours ?
• How accurate does the position need to be ? Can I just take my position from the GPS and manually enter it. I understand this wouldn't provide accurate RTCM messages, but it should switch to TIME mode / It doesn't, I tried to manually enter my rough position.
• How do I view what my std dev is ? can I monitor how Survey-In is progressing ?

Thanks !

Jon.

[Wayne Holder]

This might be useful:

  https://www.youtube.com/watch?v=FpkUXmM7mrc

Wayne

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[Jon Russell]

Yes. Thanks. I've tried to follow that video, and the SparkFun tutorial.

But he enters his position manually for the base station. He also says he hasnt had much success with Survey-In mode .. he knows the accurate location of his base station.

When I enter mine manually it doesn't switch to TIME mode.

Thanks.

[Matt Droter]

This may be a different setup from the SparkFun version.

Ardusimple GPS base station setup:  https://www.youtube.com/watch?v=qlkN70bBfFQ

To view this discussion on the web visit https://groups.google.com/d/msgid/diyrovers/692e68f7-7b99-41d9-9d89-dc82173597fan%40googlegroups.com.

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Matt Droter

ma...@droter.com

214 293-3679

[jesse brockmann]

 Have you tried contacting Sparkfun yet?  They are really good with support and maybe they can help you out.  I have gotten a chance to use mine yet.  If you keep having issues let me know and I will reach out to my contact at Sparkfun to see if I can help getting your issue resolved

Jesse

[Wayne (gmail)]

Another good resource is https://rtklibexplorer.wordpress.com/ He mostly writes about RTKLIB, but he’s done a lot of work with the F9P and may be able to help.

Wayne

On Jun 17, 2020, at 9:04 AM, jesse brockmann <jjbr...@gmail.com> wrote:



 Have you tried contacting Sparkfun yet?  They are really good with support and maybe they can help you out.  I have gotten a chance to use mine yet.  If you keep having issues let me know and I will reach out to my contact at Sparkfun to see if I can help getting your issue resolved

Jesse

On Tue, Jun 16, 2020, 5:50 PM Jon Russell <goo...@red-herring.co.uk> wrote:

Hi,

Can anyone give me some help with setting up RTK ?

I bought two ZED-F9P boards from SparkFun ages ago and every time I try to get them working, I always fail.

Lets just talk about the base station to start with ... 

IIUIC I need to know my accurate fixed position for the base station, before it will switch to "TIME" RTK mode ?

Once in TIME mode, it should output RTCM messages to UART2, which I can send to the rover RTK board on it's UART 2.

I can set the position of the base unit either manually, or run "Survey-In" ?

I cant ever get Survey-In to complete ?

I reset the base board to factory defaults. I run Survey-In using uCenter.

I tried the default std dev settings in uCenter, but that failed, so I tried something it should be able to achieve. I tried 300 seconds and 5m.

IIUIC this means it will survey for 300  second, and must achieve a std dev of less than 5m, and if so, then switch to TIME mode ?

It never completes ?

It stays in 3D mode.

<ublox.png>

<ublox2.png>

Is my std dev not less than 5m ? Is it related to one of the 3D Acc or DOP figures ? Can I get a text readout of it anywhere ?

So, questions ... 

• Have I misunderstood Survey In ? Why doesn't it ever complete ? Do I need to leave it running for 24 hours ?
• How accurate does the position need to be ? Can I just take my position from the GPS and manually enter it. I understand this wouldn't provide accurate RTCM messages, but it should switch to TIME mode / It doesn't, I tried to manually enter my rough position.
• How do I view what my std dev is ? can I monitor how Survey-In is progressing ?

Thanks !

Jon.

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[Jon Russell]

Ok, I got it working! Fresh eyes this time spotted the issue.

So, I managed to get it in to TIME mode, not using survey, but by taking the Lon/Lat/Alt readings from it in 3D mode and manually entering them in the the FIXED TIME3 setting, as described in Roby video ...

I would still like to understand how Survey-In works? I'm not sure how accurate this is, or how it will affect accuracy. Surely the postition data in 3D mode has a deviation of about 2m ? Dont I need a 10cm accurate base location to get a 10cm accurate rover location ?

However, I still couldn't get any RTCM data coming from UART2 when I plugged an FTDI cable in to it.

This video helped me spot the problem : https://www.youtube.com/watch?v=g92GboiOkeQ 

Although you have to setup UART2 in the config to output RTCM message in the "PORTS" section .. you *ALSO* have to enable the individual messages you want on each port, in the "MSG" section.

This new video showed their MSG config and I spotted that everyone uses UART1 for RTCM in the videos. But the SparkFun board has UART2 broken out on the top for a Bluetooth module, which is what I'm using.

By default, in all the configs, RTCM messages are only enabled for USB and UART1. You have to manually enable all the RTCM messages you want for UART2, then they start appearing on the port !!

Maybe SparkFun should update their learning guide, as it doesn't state this, but they use UART2 for RTCM. I dont think their current instructions will work. Well, it didn't for me. You need to enable all the RTCM messages in the MSG section for UART2.

My final Base config, added after a factory reset, then saved to flash:

  RAM CFG-UART1INPROT-UBX  0

  RAM CFG-UART1INPROT-NMEA 0

  RAM CFG-UART1INPROT-RTCM3X 0

  RAM CFG-UART1OUTPROT-UBX 0

  RAM CFG-UART1OUTPROT-NMEA 0

  RAM CFG-UART1OUTPROT-RTCM3X 1

  RAM CFG-UART2INPROT-UBX  0

  RAM CFG-UART2INPROT-NMEA 0

  RAM CFG-UART2INPROT-RTCM3X 0

  RAM CFG-UART2OUTPROT-UBX 0

  RAM CFG-UART2OUTPROT-NMEA 0

  RAM CFG-UART2OUTPROT-RTCM3X 1

  RAM CFG-MSGOUT-RTCM_3X_TYPE1005_USB 0x1

  RAM CFG-MSGOUT-RTCM_3X_TYPE1005_UART1 0x1

  RAM CFG-MSGOUT-RTCM_3X_TYPE1005_UART2 0x1

  RAM CFG-MSGOUT-RTCM_3X_TYPE1074_USB 0x1

  RAM CFG-MSGOUT-RTCM_3X_TYPE1074_UART1 0x1

  RAM CFG-MSGOUT-RTCM_3X_TYPE1074_UART2 0x1

  RAM CFG-MSGOUT-RTCM_3X_TYPE1084_USB 0x1

  RAM CFG-MSGOUT-RTCM_3X_TYPE1084_UART1 0x1

  RAM CFG-MSGOUT-RTCM_3X_TYPE1084_UART2 0x1

  RAM CFG-MSGOUT-RTCM_3X_TYPE1124_USB 0x1

  RAM CFG-MSGOUT-RTCM_3X_TYPE1124_UART1 0x1

  RAM CFG-MSGOUT-RTCM_3X_TYPE1124_UART2 0x1

  RAM CFG-MSGOUT-RTCM_3X_TYPE1230_USB 0x5

  RAM CFG-MSGOUT-RTCM_3X_TYPE1230_UART1 0x5

  RAM CFG-MSGOUT-RTCM_3X_TYPE1230_UART2 0x5

  RAM CFG-MSGOUT-RTCM_3X_TYPE1094_USB 0x1

  RAM CFG-MSGOUT-RTCM_3X_TYPE1094_UART1 0x1

  RAM CFG-MSGOUT-RTCM_3X_TYPE1094_UART2 0x1

  RAM CFG-MSGOUT-UBX_NAV_PVT_USB 0x1

  RAM CFG-MSGOUT-UBX_NAV_SVIN_USB 0x1

  RAM CFG-UART1-BAUDRATE   0x1c200

  RAM CFG-UART2-BAUDRATE   0x1c200

I'm now RTK Corrected !!

:-D

The only final question I have is should I turn on power to the antenna ?

The antenna data sheet says it's powered, but the default config on the ZED-F9P is power off.

Thanks.

[Jon Watte]

>  Dont I need a 10cm accurate base location to get a 10cm accurate rover location ? 

Yes!  But the difference in position will be consistent -- meaning, if you're off 2 meters North, the rover will be off 2 meters North, and sometimes the accuracy of the relative position traveled is more important than the direct absolute accuracy. This is true for speed sensing applications, as well as navigation/SLAM applications that have local error adjustment capability.

Sincerely,

Jon Watte


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