Goes lrit?

GNU Radio
1

Hello,

Is there any GOES LRIT decoder available under Linux and GNU Radio with
support for USRP or RTL-SDR. In case there is only USRP compatibility,
perhaps with the GRC file freely available it can be attempted to be
converted for RTL-SDR?

I have found some tools but only for POES HRPT…

Thanks,

Raydel

2

Raydel,
There was included in Gnuradio3.3 an example called usrp_rx_lrit which
has since I assume been depreciated. I have never actually used it. so I
can’t comment on how well it might have worked. It is attached here for
your reference, though I suspect it will be a major effort to get it to
work with a modern version of gnu radio.

-Ian

3

Hi,

See gr-poes-weather/apps/GOES/gui at master · mbsat/gr-poes-weather · GitHub
You need to upgrade the code to work with latest GR (to use cmake and
stuff)

To decode frames into images you need to use the RICE algorithm.

Patrik

4

Hello Ian and all,

Thanks for the attached files, i tested it but when opening it says that
some blocks are not defined, a costas loop in one case and I don’t
remember
the other one…

After browsing a little bit on the GNU Radio website I found a folder
that
includes that files, perhaps, downloading the entire folder and building
it
would fix the missing files error.

Thanks!!!

Raydel

2013/10/25 Ian B. [email protected]

5

Hi Rydel,

Right, you will first get CCSDS frames (bpsk-demodulated) let us call
that file lrit-frames.dat. To create images from the frames
(lrit-frames.dat) we need to unpack the data (lrit-frames.dat) using the
RICE algorithm to a new file say goes-13-lrit-frames.lrit. Since the
data rate is low we could rice-decode the frames (10 frames/earth disk)
on the fly, of course.

The (NASA) RICE algorithm seems to be fairly easy BUT I haven’t bothered
to try since the result (full-disk) ain’t that valuable for weather.
You’ll get nice images of Tellus, that’s 4 sure.

The RICE lib from NOAA is found here
http://www.noaasis.noaa.gov/LRIT/software.html It doesn’t link (on
linus), we’ve asked if they could release source-code so we could make
it cross-platform (last year)…

We will support you if you want to have a go. We have antennas standing
by at LA (Los Alamitos)

Patrik

6

Inorder to port it to GR the C++ code is needed (where all the fiddling
is done).
Can you give us a link?

Patrik

7

Patrick,

Thanks for the link!!! I have visited your repository before, but I
failed
to dig deeper, that’s why I didn’t found the GOES I believed it was only
for HRPT, that’s a great opportunity, I will try to build it.

Quick question, you mention I need to do RICE for obtaining images, so
if I
understand correct your application produces the frame files, a
(dot)lrit
file if I am correct? If that’s the case I can use your program for the
receiving chain, dump the lrit files into a shared folder and then
processing the images with compatibles windows programs I am familiar
too.
Am I correct?

Thanks!

Raydel

2013/10/25 Patrik T. [email protected]