Hi Amir,
you're right, the packet encoder and decoder have *long* been
deprecated, because they sometimes simply drop data. Don't use them at all.
Also, you're using GNU Radio 3.7. Don't use that to design new software,
it's really in "legacy maintenance". The current stable release series
is 3.8.x.x.
Also, at least in your loopback.grc, you should NEVER use throttle in
the same flowgraph as a hardware sink (i.e. the audio sink). GRC should
print a warning about that, unless it's *really* old.
Are you sure your audio file contains audio sampled at the same rate
that you let your audio sink sample?
Best regards,
Marcus
On 8/10/20 2:53 AM, Amir Hossein Aalipour wrote:
Hi all
As a newbie at gnuradio, currently I have two problems. I want to
transmit an audio file with gmsk modulation. I used the below
transmitter and receiver flow graphs which include packet
encoder/decoder blocks. It works but the audio I hear is "like" that
it is playing 10x faster than normal that it gets intermittent too
much and sound card can't follow it! I couldn't find why. Can you
please tell me what i have missed here?
Can the packet encoder/decoder be the cause?
I guessed maybe the packet encoder/decoder are the sources of problem
(because seemingly they are obsolete). Therefore I tried to implement
what these two blocks do. I reached at the loopback configuration
below in which I packed the data going into modulator. But it does not
work. no warning no error but nothing to hear either! then I removed
the mod/demod combination and put a tag gate block. This time it was
ok as expected of course. This shows something is wrong with the
mod/demod. I couldn't figure it out and this is now my second problem.
Please guide me to the right way.
The format object I used is:
digital.header_format_default(digital.packet_utils.default_access_code, 0)
and the endianness of repack bits block is MSB with length tag key of
packet_len.
I'm using Ettus B205 SDR boards on Ubuntu 18.04 and GRC 3.7.13.4.
Thank you in advance.
--
Amir Hossein Aalipour
MSc student of Electronics engineering
Department of Electrical Engineering
Sharif University of Technology
