remove the gui sink. It also limits the sample processing speed
and thus is equally bad as throttle.
Am 09.08.2013 19:33, schrieb Vanush Vaswani:
It doesn't help, I still consistently drop samples.
I tried increasing the buffer size in udp_source_impl.cc. I can
record to .wav perfectly for about two minutes before the flow
graph suddenly exits with (I'm assuming) a segfault.
For reference, I have attached images of the sender and receiver.
Surely, this sort of streaming has been done before? I am using a
BeagleBone Black running Ubuntu 12.04 (which runs fine - no
overflows). The correctness of the FM receiver is less of a
concern than the dropped samples.
On Sat, Aug 10, 2013 at 3:11 AM, Marcus
ok. Throttle does not _do anything_ with the samples. It
just slows down the computational speed that they are
processed with. Remove it, it breaks your flowgraph.
As said before, the WARN:... warnings stem from your UDP
source. Data does not get processed fast enough; that's
throttle's fault (before, the audio sink was limiting
your sample processing speed, which is in its nature).
Your flowgraphs are _not_ running at the same rate; they
_may_ process samples at the same average rate (that's
what throttle does, stop the sample flow when it's faster
than specified), but throttle does not convert sample
Refer to existing Receiver flowgraphs from the internet on
how to do things right, and please remember: 192kHz input
MUST be downsampled for audio usage.
Have a nice day,
Ok, I still don't understand why I'm getting so
many dropped packets.
FCDPP -> UDP Sink
UDP Src -> _Throttle_ (at 192KHz) -> WBFM
Receive -> Wav File Sink
Note: no audio sinks.
I constantly get "WARN: Too much data; dropping
Wave file is full of skips, yet both flowgraphs are
running at the same rate?
On Fri, Aug 9, 2013 at 10:37 AM, Iain Young,
On 09/08/13 00:22, Vanush Vaswani wrote:
If i add a rational resampler to match the
audio rate before the UDP
sink, I can get a continuous output, but it's
of terrible quality due to
the loss of information.
You are always going to have to throw information
away. You have 192k
that you are trying to fit into human hearing, so
you *must* filter
and then down sample.
How wide is your BPF/LPF ? Is it more than your
soundcard can handle ?
How does the
flowgraph work having a sample rate 'mismatch'
FCDPP block is in the same graph?!
Your soundcard (probably) expects 44k1. The
resampler takes care of
this, but of course, 192k is not going to go into
44k1. You need to
Could you give me a
hint in working around this issue?
As I said before, google has plenty of examples of
FM receivers with grc
(Google for gnuradio FM receiver grc, I'm sure
you'll find loads)
Here are two working flowgraphs that start at 192k
They are actually a multimode receiver I wrote
as an example for a
friend, and a multimode transceiver for ham radio
use, but they show
the FM receive chain.
With both, you'll note I have a variable BPF so I
can listen to
broadcast stations on MW/LW, and FM, SSB, or CW
stations on the amateur
For pure FM you can drop the selector blocks, and
just concentrate on
the NBFM receiver chain
Note if you need to be tuning with the FIR filter,
you'll need to define
filter taps. I used a simple LPF.
Hope that helps