Cheap hardware / simple base station for CentipedeRTK

[ffries]

Dear all,

I just discovered your project and I would like to set-up a base station for my local community in rural area in France. It would be nice along my LoraWan station to provide precise GPS. I am not planning to use precise positioning myself.

Reading the documentation Gnss receiver (F9P) is detected automatically but it would make sense to use a cheaper and older Ublox M8 chip for base. It does not sound clear to me whether ublox hardware returning RAW Output available via UBX-RXM-RAWX Message would be suitable for RTKLIB.

In particular I purchased Uputronics Raspberry pie hat: the https://store.uputronics.com/files/Uputronics%20Raspberry%20Pi%20GPS%20RTC%20Board%20Datasheet.pdf

According to docs it supports RAWX and is supported by the Raspberry Pi 2/3/4. I am also planning to use a Raspberry Pi 2B which is still available cheap new or used (RP 3 and 4 are all out of stock as of writing).

So it would make a suitable base station for 20€ (Raspberry Pi 2B) and Uputronics Raspberry pie hat (50€). Do you think it will work with RTKlib? Both are made of European components. It would drive the cost to 70€ and maybe 100€ if you find a cheap antenna.

Does it sound interesting and do you think it is worth testing?

Kind regards, FFries

[Stefal]

Hi!

• Yes, you can use a raspberry Pi 2B, or an Orange Pi Zero
• No, the Uputronics Hat can't be used. I don't think it can output the RAW stream, and it's L1 only, a things of the past for RTK.
• LoraWan usually doesn't offer enough bandwidth for a RTK correction signal.

If you live in France, do you know the CentipedeRTK Project ? RTKBase is directly connected with this open network.

[ffries]

Sorry for the confusion, I am planning to use my Lorawan casing (where I have PoE), nothing more.

Yes I am planning to join CentipedeRTK Project. Therefore I don't need a roaming solution with a base and a rover. Only a simple base (I renamed the post) to participate in the project.

The Uputronics Hat can output RAW streams as written here: https://store.uputronics.com/files/Uputronics%20Raspberry%20Pi%20GPS%20RTC%20Board%20Datasheet.pdf

Is a recent RTK chip like the F9P really needed for my project (only need a base for CentipedeRTK)?

Kind regards, Ffries

[ffries]

Here is my BOM (if the Uputronic hat is suitable) that I ordered:

• Raspberry Pi 2B (planning to use Docker): 20€ (used, my own). In France Raspberry Pi 2B/3B can be purchased on LeBonCoin easily. They are impossible to source new (at the time of writing).
• Uputronics Hat with M8 chip: 50€ (new, kubii.com)
• Waterproof casing: 15€ (new, my own)
• SD card: 10€ (new, my own)
• PoE splitter or 5V AC/DC: 15€ (new, Amazon)
• Waterproof active GPS antenna (for boating, not calibrated) with 3 meter cable: 20€ (new, Amazon)

Around 130€ total. This could divide cost by 3.

[Stefal]

If you already have this Uputronics Hat, you can play with it and try Rtkbase. If you don't have it, don't waste your money.

[ffries]

Dear Stefal, No I don't have the Uputronics Hat, but I just ordered it (before reading your message).

Are there technical reasons why we can't go with an older M8 chip for a CentripedeRTK base station? I am aware that I need to wait a few hours before reaching centimeter precision. But does it really matter ?

Kind regards, Ffries

[Stefal]

With L1 only receivers (base and rover), it take a long time to get a RTK Fix, and you will lose this Fix very easily. Moving from L1 to L1/L2 receiver is like upgrading your internet connection from adsl to optical fiber.

[ffries]

Thank you for clarification. I found this information: https://gnss.store/blog/post/rtk-ppp-and-autonomous.html

My centripedeRTK base will be mounted on a pole so it does not move.

A modern GNSS RTK receiver with two channels cost only 150EUR to 200EUR and it can reach centimeter precision in a matter of seconds. It might not be interesting to use software RTK as it can take hours an I may never reach the same precision as it is single channel. Furthermore RTK is no longer actively maintained since 2017 ... All work is focusing on hardware. Also I understand that admins are worried that I might provide bad data to the centripedeRTK project if my station moves. So it might not be possible to participate with software RTK. Simple as that ...

However I can always try and buy a new GNSS if it goes wrong.

So I am closing the issue and will report when finished.

Kind regards, FFries