Connecting the waterfall sink behind the FFT Filter causes the
waterfall to show only the filtered APT signal. Fixing this needs
an additional resampler.
The flowgraph for decoding NOAA APT images generates a waterfall with a
bandwidth depending on the default samplerate of the SDR hardware.
USRPB200 defaults to 500 ksps, which produces an output of 125 ksps
after the "first_stage_decimation" which is fixed to a value of 4.
Changing the hardware to an "rtlsdr" also changes the default
samplerate to 1 Msps which results in a waterfall bandwidth of 250 kHz
(+- 125 kHz). Connecting the waterfall sink behind the FFT Filter,
which has a decimation set to match an output samplerate of 125 kHz,
seems to be correct! This produces waterfalls with a bandwidth of
125 kHz (+- 62,5 kHz).
Fixes issue #128
* Set the loop bandwith of the PLL to a lower value, to get rid off the
DC leakage and improve SNR
* Set the AGC update rate to a higher value
* Decrease the CW decoding threshold
Add a BPSK decoder script for frames transmitted in AX.25, using G3RUH
scrambling and without. Baudrate is set via parameter "baudrate", all
filters, taps, offsets, etc are calculated using this parameter. Decoder
tested with 1k2 bps and 9k6 bps.
* Set all decoders output to binary format
* Introduce the quadrature demodulation filter in all affected
flowgraphs, in order to reduce false alarms and increase performance
There are cases where in AFSK1200 mode, the transmit source uses the
G3RUH scrambling. Now the flowgraph implements both scrambled and
unscrambled decoders, so there is no need to descriminate between
scrambled and unscrambled satellites.
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.
Seems that there is a probleb with general blocks and the history, so
the filter cannot act as valve. However, it produces zeros, in the
presence of noise.
This is an attempt to cut the signal free period after the quadrature
demodulation block. The idea seems that works, but there still an issue
with the samples not passing correctly from the valve.
Corey Shields
Manolis Surligas
Sebastian
Patrick Dohmen
Alexander Jenke
Thanos Gkiolias
Nikos Karamolegkos
George Vardakis
Vasilis Tsiligiannis