gpsd | gpsd | Version Control System library

It was a problem of different library versions. Some changes in the gps_data structure were introduced in the newer version of libgpsmm (3.22) , while I used older one. Therefore, I was getting the wrong data.

The fftw recipe is set up to create a few different packages (RPM) like libfftw, libfftwl, libfftwf, fftw-wisdom, fftwl-wisdom, fftwf-wisdom, and fftw-wisdom-to-conf. You probably want to add one or more of those. It seems there is no actual fftw package.

It is important to remember that IMAGE_INSTALL and RDEPEND lists items from the package namespace, while DEPENDS lists items from the recipe namespace.

If you are unsure about which package you want to install you can inspect the packages-split folder for fftw in tmp/work to see which files are included in which package.

For the presented input:

I don't think there is a pythonic solution, not because you can't use python but because python is not relevant to the topic. And there is no canonical solution either, everything will depend on the application.

From my experience I have found it much easier to reuse libraries that handle GPIOs like Rpi.GPIO or gpiozero. These libraries have as a strategy to create threads where the state of the pins is monitored, so you cannot use the callbacks directly to update the GUI but you must implement wrapper(see this for example).

trivial example:

How are the debug levels set?

A call to the library routine gpsmm_enable_debug() according to the GPSD Client HOWTO. Refer to Table 1.

A quick and dirty way would be to start gpsd with the -G option, to enable monitoring all interfaces (by default, gpsd will only listen to localhost for security and privacy) and then disable access on unwanted interfaces by having proper firewall rules (disable access on two unneeded interfaces). Gpsd will listen on port 2947, you can change that with the -S option to fit your needs.

/proc// is a filesystem-like view on the process , exposed by the kernel.

As such, the only way to remove/add/change anything within this directory is by changing the process itself (in your case: make the process close the offending file-descriptor to have the corresponding symlink go away).

The other way is to patch the kernel, but you probably don't want to do this.

After tinkering (i.e. compiling from source, installing, configuring, testing, etc.) with gps-share, Gypsy, geoclue2, serialnmea and other ways to access data from a GPS connected to a serial port (thanks to Pa_ for all the suggestions), but all with no results while gpsd was working perfectly for other apps, I decided to make Qt support gpsd by making a very crude change to the QDeclarativePositionSource class to implement support for a gpsd scheme in the URL for the nmeaSource property. With this change, a gpsd source can now be defined as nmeaSource: "gpsd://hostname:2947" (2947 is the standard gpsd port).

The changed code is shown below. I would suggest this should be added to Qt at some point but in the meantime, I guess I need to derive this class to implement my change in a new QML component but, being new to QML, I have no idea how that is done. I suppose it would also probably be a good idea to stop and start the NMEA stream from gpsd based on the active property of the PositionSource item... I will get to it at some point but would appreciate pointers on how to do this in a more elegant way.

system_clock and NTP both "handle" leap seconds the same way. Time simply stops while a leap second is being inserted. Here I'm speaking of the time standard, and not of any particular implementation.

An implementation of NTP might not stop for a whole second during a leap second insertion. Instead it might delay itself by small fractions of a second for hours both before and after a leap second insertion such that the sum of all delays is one second. This is known as a "leap second smear".

So you could say that both system_clock and NTP ignore leap seconds in that if you have two time points t0 and t1 in these systems and if t0 references a time prior to a leap second insertion and t1 references a time after that leap second insertion, then the expression t1-t0 gives you a result that does not count the inserted leap second. The result is 1 less than the number of physical seconds that has actually transpired.

A GPS satellite "ignores" leap seconds in a completely different way than system_clock and NTP. The GPS "clock" keeps ticking right through a leap second, almost completely ignoring it. However GPS weeks are always exactly 604,800 seconds (86,400 * 7), even if a leap second was inserted into UTC that week.

So to convert GPS weeks (and GPS time of week) to UTC, one has to know the total number of leap seconds that have been inserted since the GPS epoch (First Sunday of January 1980). I believe gpsd does this transformation for you when it provides you a UTC time point.