[Discuss-gnuradio] Digital Audio Broadcast (DAB), anybody running gr-dab?

[Matthias Weber]

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data (old reference to [5] also seems to be outdated).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] https://github.com/andrmuel/gr-dab
[2] https://github.com/gzm0/gr-dab
[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