« Return to Thread: The state of RTCM3 support, and two request for healp

The state of RTCM3 support, and two request for healp

by Eric S. Raymond :: Rate this Message:

Reply to Author | View in Thread

I have spent the last week or so adding RTCM3 support to gpsd.  But
I don't have an RTCM3 source and RTCM3-capable GPS to test with,
so I need some help verifying that the support is correct.

Enhancing the packet sniffer to detect RTCM3 packets was not
difficult. They have a well-defined framing protocol with a unique
leader byte and a strong checksum (actually, the best checksum
algorithm I've ever seen). The RTCM3.1 standard includes a hex dump of
a good test packet.  Thus, I have high confidence in the support at
the packet-sniffer level.

I am fairly sure that gpsd will correctly pass RTCM3 packets from a source
to all attached RTCM3-capable GPSes, but only because the code to do
that was trivial once the sniffer changes were in place -- I basically
cut and pasted the RTCM2 passthrough support.  But this needs to be
tested.  

To test RTCM3 passthrough, somebody needs to run gpsd at a high debug level
with the right equipment attached (an RTCM3 source and an
RTCM3-capable GPS) and verify by looking at the <= and =>  that the
right thing is happening.

Testing rtcmdecode's facility to analyze and dump the contents of
RTCM3 packets is more difficult; in fact, right now I have no way to
check the correctness of that code, and it is almost certainly wrong
in some of its details. I've tried to follow the 10403.1 standard as
closely as possible, but getting this sort of thing perfect on the
first try is notoriously difficult and I doubt I have managed it.

Just having a binary RTCM3 capture isn't good enough.  To verify this
code I need both a capture and a set of testable assertions about what the
the data in it means -- ideally, an ASCII dump of the data fields in the
capture produced by a tool that is known good.

I haven't actually finished the analyzer code, because there doersn't
seem to be a lot of point in trying before I can test it.  Can anyone
supply both a binary RTCM3 test load and some sort of text dump of at
least the key data in it?
--
                <a href="http://www.catb.org/~esr/">Eric S. Raymond</a>

The whole of the Bill [of Rights] is a declaration of the right of the
people at large or considered as individuals...  It establishes some
rights of the individual as unalienable and which consequently, no
majority has a right to deprive them of.
         -- Albert Gallatin, Oct 7 1789
_______________________________________________
Gpsd-users mailing list
Gpsd-users@...
https://lists.berlios.de/mailman/listinfo/gpsd-users

 « Return to Thread: The state of RTCM3 support, and two request for healp

LightInTheBox - Buy quality products at wholesale price!