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

[Gary E. Miller]

Yo Florian!

On Thu, 30 Apr 2020 12:49:14 +0200
Florian Kiera <address@hidden> wrote:

> Thanks to Greg I am now able again to use gpsd to receive the
> correction data from my NTRIP Caster. (the NTRIP Caster stream is
> good again!)

Good news.

> To give a short explanation how I solved my issue before:
> Greg gave me a huge hint to check out net_ntrip.c line 453. (You
> might already know:) In this line it checks the "ICY 200 OK"
> feedback. However, because my caster sends "ICY 200 OK\x0d\x0a" gpsd
> counted it as error and closed the connection. I just changed
> net_ntrip.c line 33 '#define  NTRIP_ICY "ICY 200 OK"' to "ICY 200
> OK\x0d\x0a", installed it anew and now the "good stream" works again.

This make no sense.  The strstr() only checkes the leading part of
"ICY 200 OK", so any trailing data is ignored.

Why would strstr() match the longer string and not the shorter one?

> Later I will try to change it on the ntrip casters side to not run a 
> "custom ugly solved" gpsd.

Most people can not change their casters.  Many are run by universities
and governements that do not change quickly.  Best to make gpsd work
with more casters.

> The receivers computer
> seems to be the unstable thing here. After some time and odd outputs
> in dmesg, it kicks and adds the receiver to a new port address
> (ttyACM1 cause ttyACM0

Sadly this is a common USB failure.  Be sure you receiver is connected to
a UBS 2.0 port, not a USB 3.0 port, and has lots of spare power.


> is still used by gpsd) which, of cause, gpsd
> cannot find dynamically.

gpsd can handle that case if your udev is properly setup.

> gpsd:ERROR: Write to RTCM sink failed, type u-blox
> gpsd:ERROR: SER: device open of /dev/ttyACM0 failed: No such file or 
> directory - retrying read-only

Should be obvious why.

> [10994.628969] usb usb3-port1: disabled by hub (EMI?), re-enabling...

Try a different hub.  I have yet to find a USB 3 hub that is reliable.
More than a few USB 2.0 are also falkey.  I have tried many.

> So it all didnt worked due to the odd output "ICY 200 OK\x0d\x0a"
> (the hexadecimal "ok" is odd)

Not odd, that is just CR, LF.

> As always the solution must've been that simple... UGH. Thank you for 
> your patience and tips!

Sadly, we are not done yet.  This still doe snot smell quite right.

> P.S. I only used "gpsd -G ntrip://usr:pw@ip:port/STREAM" to test if
> gpsd is able to open a stream to my caster. That gpsd lacks a
> receiver here in this command is clear. It just had testing purpose
> (learning gpsd in small steps) and didn't unnecessarily spammed me
> with the receivers NMEA/TPV output.

fgrep is your friend.

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
        address@hidden  Tel:+1 541 382 8588

            Veritas liberabit vos. -- Quid est veritas?
    "If you can't measure it, you can't improve it." - Lord Kelvin

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