This commit adds a hierarchical block that performs Doppler
compensation and resampling.
Rather than using directly the available Doppler correction blocks,
based on the user parameters of the incoming sampling rate and the
desired target sampling rate, it applies proper decimation on the signal
so the frequency shift to be applied to a smaller sampling rate,
reducing significantly the CPU resources required. At the previous
architecture (gr-satnogs 1.x.x) we used seperate blocks for the doppler
correction and the LO digital shift, operating at the device sampling rate.
These two blocks, performing almost the same operation, contributed to a
30% CPU usage of the overall application. Now the LO is compensated by
the Doppler correction block, taking into account at the same time the
Doppler drift.
After the digital LO shift, the Doppler corrected signal is passed through
an Polyphase Arbitrary Resampler, to match exactly the sampling rate
requested by the user.
The new GNU Radio linkage system seems that has some
issues. There are linkage dependencies that they should
be private on the GNU Radio target.
In addition, find_package(Boost) is also called on the
gnuradio-runtime target. Calling it again in the OOT
module overwrites the existing list of dependencies,
causing many problems.
We are staring a process of dropping Boost and use
the C++11 variants.
To allow easier integration to the new architecture the
multi format file sink supports bot legacy and the new
format of the PMT messages. In poth cases, only the PDU
is extracted. Legacy used the PDU as a BLOB, whereas
now the PDU is stored in base64 format inside a
dictionary, which structure is defined through
the gr::satnogs::metadata() class
The decoders produce a PMT message containing several information about
the decoded frame. While this is very convenient for handling data
inside the flowgraph, it is not for third party applications. The JSON
converter block is responsible to serialize all the information
contained in a PMT originating from a decoded frame.
For simple demonstration some metadata were added on the AX.25 decoder.
These metadata are still a WIP and they subjected to changes.
Some distros do not contain the GrVersion.cmake module so the git
version can be applied into the gr-satnogs version reporting script.
This commits adds this module into the project, so the build system can
use it during project configuration.
The new BPSK decoder uses a blind equalizer in par with an LMS based
equalizer. Both of them adapt more quickly in the channel response than
the AGC.
The decoder supports baudrates up to 19200.
Note that the bpsk_ax25.grc deprecates the bpsk_decoder.grc and
bpsk_demod.grc and they will be removed on the next release.
The CMake build system will first try to locate libfec in the system. if
it is not available, it will start building the libfec that is part of
the gr-satnogs source code. During the installation libfec is installed
in the system, thus future builds will make use of it and will not
rebuild from source.
fm_demod script that also writes waterfall data (credit to surligas, I'm just committing)
Also FFT needs to be added to CMakeLists.txt to build in some conditions.
see also satnogs/gr-satnogs#42
* UDP Message source can handle multiple data types
* Add a waterfall sink block
* Fix dependency issues with VOLK
* Add mean and max hold mode to the waterfall sink
* Add mean and max hold mode to the waterfall sink
* Install satnogs_waterfall.gp gnuplot script at
<install_prefix>/share/satnogs/scripts
* Automatically retrieve x and y axis ranges at the satnogs_waterfall.gp
Now, with the Morse code debug source block the testing of the decoder
can begin.
Add at the examples directory a small flowgraph that connects the debug
source block with the decoder.
Depending the received symbol the tree is traversed towards the leafs.
At each step the corresponding decode-able character is appended at a
string buffer.
TODOs:
* Add logic in the decoder to retrieve the decoded words from the tree
* Create a debug source block
Manolis Surligas
Sebastian
Kostis Triantayllakis
Alexandru Csete
George Vardakis
Manolis Surligas
Corey Shields