On Wed, Jun 13, 2012 at 8:15 PM, Phelps Williams
<address@hidden> wrote:
I have a simple bpsk transmitter setup with a custom udp source block
which outputs a fixed pattern if no data is available from the socket.
I have instrumented the block to indicate when data is read from the
socket inside of work().
My radio looks like this:
Custom UDP Source -> DPSK Mod (DBPSK, 10 samp/sym) -> Multiply Const
(0.3) -> UHD: USRP Sink
My sample rate is 1e6.
I can tell from my instrumented UDP Source that udp traffic is handled
by work and passed on almost immediately. However I can tell from
both monitoring the spectrum and the receiver output on the other side
that the data takes between 7 and 10 seconds before I see the expected
output from the N200. I thought this could be improved by reducing
the maximum socket buffer size (sudo sysctl -w
net.core.wmem_max=5000000) but that didn't seem to make a difference.
I went as low as wmem_max=10000 with no difference in delay. My goal
is to get the total delay to < 1sec.
What else could be adding delay to my transmission path? Are there
other buffers I can tweak? Where else should I be looking?
Enabling logging in:
gnuradio/gnuradio-core/src/lib/runtime/gr_block_executor.cc
... by changing the line to:
#define ENABLE_LOGGING 1
... might produce some interesting data to evaluate what is going on.
Let us know what you learn. Thanks.