On 03/05/2023 14:04, Marcus Müller wrote:
Hi Fabian,
I'd write a block that copies a stream in- to output. It might query
gpsd every time the work() function is called, or have a FIFO into
which data from gspd is being pushed by a separate thread (or by
reading from a socket or however gspd works, I must admit I'm not sure).
You then take that info, and encode the long, lat, uncertainty as
(double, double, double) PMT tuple. You then use add_item_tag to add
that PMT to the first sample in your output buffer.
You'd feed the result into a metadata file sink block: That saves
things in a serialized format ready for retrieval.
Best,
Marcus
On 5/3/23 19:52, Fabian Schwartau wrote:
Hi everyone,
I am trying to record some data from an SDR and would like to
sync/tag the data with the current gps position from gpsd. I am kind
of stuck and don't know how a possible solution for that might look
like in grc.
I have a python function that gets the current position as a tuple,
but how do I get this into my data stream, which I would like to
write to a CSV file or similar?
I am not asking for a solution of my problem, just point me in the
right direction ;)
Best,
Fabian
Quite apart from the GPSD-specific stuff, it would be useful to have a
kind of "annotated formatted data" file sink for low-rate
data (like scientific data, etc) which supports CSV outputs, and has
some way of ordering any tags that come in with the
data and formatting them appropriately, but still be reasonably
"generic" (in that the block doesn't really *know* anything
about the tags, and can be told how to format them). Maybe *in
addition* you could pass the block a series of methods to
call at some configurable cadence.
This somewhat overlaps with what SigMF tries to do, but this is
formatted data, inherently low-rate, with formatted
annotations.
I nearly always end up doing this in a custom way for my applications,
but having a generic block would be cool, and not
hard to do. Could be entirely in Python, since we're talking "low
rate" (like perhaps a few per second at most).
