Comments: GPS-RTK2 Hookup Guide


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  • What's the max altitude this thing is good to?

    • You mean the ZED-F9P? It's on the features tab:

      • Max Altitude: 50km (31 miles)

  • Hello, the "Getting started with U-Center" link is broken. It should direct to

  • Hello, first of all, thank you so much for providing such a detailed tutorial. Our research group is planning to use RTK GPS on a ground mobile robot. I checked the availability of nearby correction base stations and I could not find any stations in the 20km range. I am planning to use the ZED-F9P module as the base station and the ZED-F9R module as the receiver. I understood the base station set up part, but I could not figure out how I can transmit the RTCM correction signals from the base station to the receiver? I believe the receiver needs the RTCM signals on any of the serial ports. Could you explain how can I transmit the RTCM correction signals?

  • Would like to verify my understanding. I planned to setup my Base station/Rover similar to the "Setting up a Rover Base RTK System" article, but (on Rover side) instead of obtain NMEA information via USB-C port I can get it via UART1, is that correct?

    • Nate / last year / 1

      Short answer is yes, you can get RTCM over UART1. On the rover side, the ZED-F9P's default setup to receive RTCM over UART1, UART2, USB, and I2C. This can be turned on/off.

      Most projects (that use a radio to pass correction data) use UART2 for the RTCM connection between Rover and Base but you can use really any port on the ZED you'd like.

  • If I understand this right, for best accuracy (without internet connection) and assuming I can provide data link between the two, I would need at minimum two GPS-RTK2, one setup as a base station programmed to produce RTCM data and other setup to listen for this data, is this correct? Can two GPS-RTK2 be setup this way? If so, I understand that weather conditions play a big role when determining RTCM data, can GPS-RTK2 achieve 10mm accuracy in such setup on cloudy day? If not, how much accuracy can get lost?

    • Yes you need two. Yes one can be programmed as a base and a rover.

      I don't think a cloudy day will have much impact on accuracy. There's plenty of disturbances you cannot see (ionospheric stuff) that can be corrected for. The rover unit report horizontal accuracy and I've never seen anything less than 14mm with RTK Fix.

      • Ok, because we can use one GPS-RTK2 as "Correction Source", is RTCM data from this sensor same quality as data from other RTCM providers such as UNAVCO? Also, does setup for "Correction Source" requires any manual position input from the user or does it have self-positioning ability?

  • "There seem to be NTRIP apps for iOS but we have not been able to verify any one app in particular. If you have a favorite, please let us know."

    YES, there are (free) NTRIP client apps for iOS... but according to your support team, "Apple requires Bluetooth devices that connect to Apple products to be MFi certified and that's something that Apple charges manufactures to add to a product. Unfortunately none of the Bluetooth modules we[Sparkfun] carry are MFi certified and usually won't connect to an Apple device." Might be worth mentioning that here in the hookup guide, and also on the bluetooth board specs pages to save other folks the headache I just went through.

  • Hi,

    Has anyone succesfully connected this GPS to LabVIEW through I2C?


  • With the board in base station mode, would it be possible to connect a 'UART to RS232' adapter on UART2 to send corrections to a device that accepts RTCM3? I'd use an RS232 radio modem to transfer the data long range.

    • Yep. A MAX3232 or equivalent circuit would convert the TTL serial to RS232 serial. That serial could then be physically attached to an RS232 long range radio.

  • I followed the hookup guide for to a correction source using the bluetooth mate and the lefebeure ntrip client. Everything worked great the first time. I shut everything down for the night and when I tried to hook up again today I can't connect to the board at all. When I try to connect via usb in u-center the error message simply says "Can not connect to COM9 9600". I tried disconnecting the bluetooth and get the same result. Any ideas?

  • Hello, I'm a student and for my university project I have to setup a RTK system in base - rover configuration using a device like GPS-RTK2. I'm a newbie in this field and after I read the hookup guide and some other stuff on internet I still have some doubts about the configuration of the system.

    The system that I imagine is composed of: 1) A base compose with GPS RTK2 + antenna connect through USB to a PC. On the PC a program like u-center (or other like RTKLIB or SNIP) collect the data and works as NTRIP server/caster and sent the corrections through internet to the rover. 2) A rover compose by GPS RTK2+antenna+Bluetooth module recives the stream via Bluetooth from a smartphone that runs an NTRIP client like Lefebure app and through USB connection power up the board. Could it works? Any advices it's really appreciated, thank you very much and sorry for my english! Luca

    • I'm not sure if I understood your question because "your system" sounds exactly like the information covered in this tutorial (maybe I missed something). For further assistance, please post a new topic on forum and we will do our best to assist you.

  • Hello,

    I don't have acces to free real time RTCM corrections, but I can download for free one hour old RINEX files from the nearest RGP (IGN reference station network, France) base.

    So I'm thinking about make a custom base station.

    • Would it be possible to record the data received by sparkfun GNSS hardware as a RINEX file, for post processing with RTKLIB and compute the accurate position of my custom bas base ?

    Thank you !

    • I'm not quite sure if I understand your question. For assistance, please post a new topic on forum and we will do our best to assist you.

      (*Also, please elaborate on the details of your project in your post. Currently, from my point of view... I am interpreting it to mean several different things depending on where the "sparkfun GNSS hardware" is located.)

  • Hi Nate,

    I'm currently a student doing an internship. There are a few things that I do not understand about your guide. Perhaps you could help me out? How does the rtk rover receive the rtcm correction data? Through what medium? Isn't the rtk obtaining the rtcm data the same as delivering the rtcm data to rtk? What's the difference? Is a correction source a base station? Or does the base station need to connect to the correction station?

    Here in the netherlands we have 06-gps. It is a company that provides their correction from their base station/correction station. They send the data through cellular data 3G or 4G. I assume that I need a modem to receive that data. How do I integrate that into the rover? What microcontroller do I need for that? How can I process that data from the microcontroller to the ntrip client?

    Thank you! Damian

    • Many good questions. Let me try to answer them.

      How does the rtk rover receive the rtcm correction data?

      You send RTCM binary data via a serial connection over UART2.

      Through what medium?

      Your choice. You could use a laptop to send RTCM data via serial to the RTK2, or you could use a cellular module to pull it down from the internet and send the RTCM data via serial to the RTK2.

      Isn't the rtk obtaining the rtcm data the same as delivering the rtcm data to rtk?

      It depends on the mode you've set the RTK2 to be in. If the RTK2 is stationary, you can put it in survey mode and it will begin producing RTCM corrections but it cannot then begin to move and have centimeter accuracy.

      Is a correction source a base station?


      Or does the base station need to connect to the correction station?

      If you have an available correction source (from a company, from someone else's base station, from a government run GPS station, etc) that is within 10km of your rover then you do not need a base station - just use their RTCM stream.

      They send the data through cellular data 3G or 4G. I assume that I need a modem to receive that data. How do I integrate that into the rover? 

      That's a very large topic that can't be answered in a comment. I recommend starting by reading the hookup guide for our LTE shield to find out how to pull data down from the internet.

  • Nate, When using the low cost magnetic GNSS antenna were you able to receive any L2 signals or were they all blocked by a filter? I look forward to seeing some multi-band antennas show up!

    Thanks! Tom

    • Our low cost antennas can only received L1 bands; the frequencies are far enough apart the GNSS antennas simply don't pick up any signal in L2.

      (edit) We've got the L1/L2 band antennas posted now.

  • Nate, i have two of your rtk2 boards and two blutooth mates arriving today. I’ve looked all over for an iOS ntrip client for iphone, but can’t find one. Can you recommend one? I guess i could run rtklib (strsvr) on a laptop and stream to the rover bluetooth, but would be much cleaner if i can just use my iphone as ntrip client. Thanks! Don

    • Unfortunately I don't have a good recommendation. After a quick look, most of the IOS apps look like the are closed down to only work with a given set of RTK hardware.

      An open source NTRIP mobile app is badly needed in this world.

      • Same thing i found. All the ones i saw required specific hardware. So i’m not seeing a way to use the two Bluetooth Mates i’m getting today with my iphone. Bummer.

  • What antenna did you use in your demo with this GPS? It needs to be a GNSS multi-frequency antenna. Does Sparkfun provide one?

    • I did most of my testing with our low-cost magnetic GNSS (with ground plate) and achieved the 17mm shown in the image.

      We currently carry GNSS antennas but no multiband units yet. I'm hoping to get one listed on SparkFun in 4-6 weeks.

      (edit) We've got the L1/L2 band antennas posted now.

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