[Question] gpsd, ntrip & C94-M8P (u-Blox)

[Florian Kiera]

Hello there, I got a question regarding to the use of correction data in 
gpsd.

Using latest Arch Linux (5.6.6) and the latest gpsd version (3.20).

I am using a C94-M8P from u-blox to receive DGPS-information (RCTM3) and 
transfer it via ntrip to another PC that is connected to a 2nd M8P that 
is moving around.
Its supposed to send correction data via the ntrip caster to the moving 
PC's M8P. The fixed station part works, however using the command: "gpsd 
-n /dev/ttyACM0 -G ntrip://:@IP:PORT/STREAM" only puts the information, 
the ntrip caster is giving out and the M8P is giving out, into the PC 
itself but not to the M8P (the USB port since it is not addressed at 
that point?). What worked for me was using RTKlib's str2str that uses an 
input stream (ntrip caster) and gives it to the output stream (the USB 
port of the M8P). But using this command won't allow me to access the 
exact data of the moving M8P because the port is already used to receive 
correction data. GPSD would be able to give the correction data from the 
ntrip caster to the M8P (atleast what the information of the manual 
tells me) and ALSO receive the corrected exact coordinates of the M8P 
(the 2nd M8P uses the RCTM3 messages and its own coordinates to give out 
an accurate position in NMEA) and write them into the shared memory so I 
might be able to use them for my CUI.

So my question is: Whats the correct use of gpsd to send and receive 
correction data from different sources (receive from ntrip, send to 
USB)? Do I need to change any settings of gpsd to tell it that M8P is 
able to use the RCTM3 data or something like that?

Regards, Florian.