Hi all!
Yesterday I tried to investigate on DAB reception. I have searched the
list archive for discussions about DAB in reverse chronological order.
Unfortunately It did not really help out.
I stumbled across two gnuradio-related projects [1] and [2]. [2] has
last change several years ago. [1] has last change 7 months ago and is
written by Andreas Müller (put in BCC) who also wrote a semester thesis
[3] about DAB - Software Receiver Implementation which is quite good!
Also stumbled across references to [4] which is no longer available.
I tried to build an run the scripts in ./apps. I was not able to receive
successfully:
The execution of usrp_dab_rx.py returned several warnings:
gr::buffer::allocate_buffer: warning: tried to allocate
4 items of size 16000. Due to alignment requirements
32 were allocated. If this isn’t OK, consider padding
your structure to a power-of-two bytes.
On this platform, our allocation granularity is 4096 bytes.
This might be okay, but I did not allocate where this came from.
Afterwards I get several errors saying “FIB CRC error” coming from
./lib/fib_sink_vb_impl.cc function
gr::dab::fib_sink_vb_impl::process_fib. [“FIB” standing for Fast
Information Blocks that make up the Fast Information Channel (“FIC”)]
Verbose mode hints the following phase variance and signal quality:
→ Phase variance: 0.202296033502
→ Signal quality: ======================>----------------------------
Is it still good enough for reception? May the error also be due to the
use of DAB+ instead of DAB because of the use of a different channel
code? I think so.
Can anybody say that he or she is using gr-dab successfully at the
moment? I am not sure if this is an RF reception or software problem.
From my point of view the spectrum rather “looks good”. If required I
could also upload some raw IQ data (old reference to [5] also seems to
be outdated). Or maybe somebody else could also provide samples to
compare?
The hardware I was using: both an USRP N210 and a rtl-sdb dongle with
different antennas and antenna locations.
Just found a note right now: “the patch in
patches/not_applied_in_trunk/gr_peak_detector_XX.cc.t.diff must
be applied to the GNU Radio trunk before building” - is this still the
case? The problem is that I am currently using Gnuradio 3.7.2.1 Debian
packages in Linux Mint.
I am grateful for any hint as there is many parameters that may be
wrong, thanks.
Matthias
[1] GitHub - andrmuel/gr-dab: GNU Radio DAB (digital audio broadcasting) module
[2] GitHub - gzm0/gr-dab: GNU Radio DAB (digital audio broadcasting) module
[3] http://0x7.ch/text/dab-report.pdf
[4]
http://www.zhaw.ch/de/engineering/institute-zentren/zsn/projekte/gnu-radio.html
[5] http://www.opendigitalradio.org/files/dab_mode1_basicrx_2msps.cf.bz2