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Simple F9P (rtk) howto

Posted by grin on 14 November 2021 in English (English). Last updated on 21 November 2021.

Simple uBlox F9P howto

I got a question about specific usage of the F9P from zero to hero, so, here’s some summary from the beginning.

It is simple and almost hassle-free.

I got my board from uBlox directly but I guess it works the same with all the F9P boards. The board came with an external antenna (if you don’t have that you definitely have to find a good one, makes a lot of difference), and an USB-B cable for power.

As for the hardware, you need:

  • power source; I am using a 10 Ah powerbank which is enough for 10+ hours (probably even more)
  • a box, to put the board into, and preferably stable within, either by screws or some foamy stuff. The connectors are said to be sensitive, so try to find a way to relieve any stress on them.
  • for the external antenna you should find a way to keep it at the top seeing the satellites. My antenna has a strong magnet and I got a metal plate so I usually put the antenna outside of the top of my backpack sticking to the metal plate inside.
  • You need a mobile phone with bluetooth. Preferably Android, since I can’t help with iAmrich models. (Theoretically you could use a laptop but, uh.)

The board does not really need any setup, but there are freely available windows® programs turning the internal knobs. Since the board came with Bluetooth enabled I didn’t need to fiddle with settings (but I’m a fiddly type, so I have, but you don’t have to).

For the phone you need an app which can

  • connect to the board by bluetooth
  • able to retrieve an NTRIP stream from the network (about that later)
  • can send the stream to the board
  • can retrieve the NMEA log from the board
  • and preferably can provide mock locations for the phone.

There are two free apps available at the moment I am aware of:

  • Lefebure NTRIP client is an older, non open source program which works quite well but has the nasty habit of disconnecting and never reconnecting
  • Bluetooth GNSS is an open source program which shows a bit less logs but way more reliable, and the author is more responsive. I suggest using that one.

Also you need continuous internet connection on your mobile to get realtime position. (In fact you can do it offline by recording the raw GPS stream and later use correction with NTRIP but that’s way beyond this howto.)

You need an NTRIP stream

You need an NTRIP stream, which is an internet service sending you atmospherical corrections from a Base station through a continuous TCP stream. There are countless services selling you that for a lot of dineros, but there are some nice people providing freely available streams.

I am using EUREF-IP, which has a perpetually dying chain of webpages, right now it seems to be available through, but may be accessed through or or else. You have to request access to the streams on this page and they usually respond within days. You need a bit of luck to find the streams for this specific login, I am using TCP/80 as a server with the login they accepted.

As StephaneP mentioned there may be a lot of other freely available streams, or community provided streams - generally you need a base station as close to you as possible. It may work from 300 km but way better within 10 km. Search… (Check the maps on

Enable mock locations for Android

To let whichever app to see/use your location you have to enable Developer options on your Android (it needs no root or modification, just a few clicking, google it), then enable your NTRIP app to provide Mock locations.
This will let you to use any of the usual apps, like OsmAnd.


At this point you are ready. Power up the board, go outside to see some satellites, then fill out the data in the app (stream server and port, login name and password, and the NTRIP station you chose). Then connect to bluetooth of the board, and the app shall start retrieving NTRIP from the internet, send to the board, and get GPS data. You will probably see a DGPS fix pretty soon, and if your NTRIP stream fits your atmosphere and you stay put you will have FloatRTK or real RTK fix within minutes. And the location will be seen in OsmAnd or navigation or logger or else.

You go and start mapping.

At the end, you stop track recording, then disconnect the app from bluetooth then disconnect power from the board. Then you process and upload to OSM. :-)

[Update]: It is usually useful to request your NTRIP app to log the GPS stream (usully NMEA), because it may contain more precise information about the fix type, which help you later when you are mapping. JOSM has nice setting to display GPS tracks with precision circle showing how precise the GPS unit thinks the measurement was. It is usually reliable, but the more money you pay for something the more reliable it is, and since F9P is a midrange chip it sometimes make mistakes; I have seen 1-2 meters error when moving but for non-moving measurements I haven’t seen any errors so far.

Real Time Kinetics

Posted by grin on 3 November 2021 in English (English).

Real Time Kinetics (RTK)

For half a year now I’m walking, biking and generally moving accompanied by an uBlock F9P unit, which is a precision multichannel GPS receiver board with an external antenna and bluetooth connection to my mobile phone. The phone receives correction stream (NTRIP) by mobile net and uploads it to the unit, which in turn uses the correctional data to fix up atmospheric noise in the GPS signal.

The result is a GPS position way more precise than a phone.

There are 3 usual states:

  • RTK - or “Real Time Kinetics”, when there is both satellite and internet data is available, and the base station of the stream is near. It means precision between 50 centimeters up to 5 centimeters! Imagine it like not only it’s visible when I go to the other side of the path but the track even show when I turn around, since my backpack makes a 30 cm circle around. :-)
  • FloatRTK - is when the precision “floats” from a known-good position, which in practice mean 1.5 meters up to about 90 cm (on average 1 m). When I am within 100-300 km of a base station and I’m moving in a forest this is the most usual state.
  • DGPS - when there is no RTK fix (usually due to no mobile network or blocked satellite receiving) the “normal” differential receiving mode is active, which means 3m - 1m precision, closer to 1.5 m on average, thanks to the external antenna and multichannel receiver.

When I am on FloatRTK or RTK it’s amazing: it can get back to the same position everytime, later on the day, or on a different day, which basically mean that the position is exact. I can draw a track with 50 cm precision and try not to draw that much detail on OSM (not to make anyone mad seeing fixes of centimeters along :-)).

Unfortunately there are no miracles: on the bottom of a gorge (say, recent beautiful Slovensky Raj) or with no mobile network the float become DGPS fast, and precision starts to wander. HDOP is not a reliable measure: while the “guesstimate” is usually a few meters there are places where my track diverges from satellite imagery too much to be trusted. (So, for a specific example, I wasn’t able to precision-fix up Slovak gorges since there was no network coverage in the middle of nowhere.)

When you see accuracy=* on my tracks it usually mean I had FRTK or RTK there and the position is pretty accurate, way more than a mobile phone can reproduce. Still, if you have an industrial receiver you may be better than me, and feel free to fix up points and tag accuracy=* accordingly. :-)

Hardware and software:

  • uBlox F9P + 10Ah powerbank
  • Bluetooth GNSS (Android) [logging NMEA, sending position to android and uploading NTRIP to F9P]
  • Free NTRIP casters from or
  • OsmAnd
  • and an android phone with mobile net and a largish battery (+powerbank backup).


Massive thanks to the Hungarian OSM Community, and especially Kolesár to research the receivers and usage, finding software and streams, to make it all possible.

Posted by grin on 9 November 2010 in English (English).

I think I'm guessing right that those LOTS of GPS tracks with wildly detailed street coverage in selected Hungarian cities which simply isn't drawn in the OSM map are actually offered by ( team for OSM.

If so, they're simply Great Heroes.

Vă mulţumesc mult!

Location: North Great Plain, Great Plain and North, 4200, Hungary


Posted by grin on 9 November 2010 in Hungarian (Magyar).

Na jó, megbarátkoztam a JOSM-mal. Vannak irritáló hibái, de most, hogy sikerült beizgatni alá a slippymap-et is meg a yahoot is, egész használható.

Bár agyamra megy, amikor belassul...

Anonymus a Hős

Posted by grin on 4 November 2010 in Hungarian (Magyar).

JOSM tesztelésképp ránéztem „szülőfalumra”, Hajdúszoboszlóra, és láttam, hogy igen katasztrofális állapotban van. Előfordul.

Alaposabban megnézve azonban azt láttam, hogy bár az OSM térképen szinte semmi nincs, valaki gyalog bejárta az egész várost, alaposan, pontosan, szisztematikusan; ebből azonban semmi térképet nem láttam.

Meg tudom valahogy vajon nézni (nyilván HA van a track-hez id adat) hogy ki csinálta? Vajon miért nem rajzolta fel a térképre...?

Másrészt furcsa effektus, hogy SzPaula főútjai mintegy 50m-re vannak a GPS trackektől, szisztematikusan. Higyjek Paulának a GPS ellenében? (Nem tettem, de meggyőzhető vagyok.)

Mindenesetre 'Szoboszló jelentősen jobban néz ki. Elfogyott a türelmem az utcanevekhez, talán majd egy helyi vagány folytatja. (És persze elfáradtam az egymást keresztező utcákban meg vonatsínekben...)

De jó, hogy van róla valami, köszönhetően a Névtelen Hősnek, Aki Bejár.

Location: Észak-Alföld, Alföld és Észak, 4200, Magyarország


Posted by grin on 26 September 2009 in Hungarian (Magyar).

Itt látható egy példa az utcák számozására:

Itt pedig egy meredekségre, ami persze nem renderelődik le:

De ez is kapott egy mókás (valid) taget (Way 40694574):


Posted by grin on 11 September 2009 in English (English).

So I finally exported some GPS tracks and tried to check around. LOTS of white, unmapped areas, some of them unfortunately so much unmapped I cannot even cut the proper roads apart. At least I entered some pivot places to start from. Lazy bastards around Veszprém for example. ;-)

Still no useful aerial of Debrecen, and I have no saved tracks from there. Darn.

On the bright side I've done my first roundabout. Looks ugly. :-(


Posted by grin on 22 May 2008 in English (English).

Hmm, well, well, this project has been hiding from me till now. I love the idea. Seems very time consuming waste of time, love it. I have no time, so this may help my struggles to meet universal enlightenment by wasting more time than I have and disappering into Nirvana with a loud *pop*. :-)