Hi Martin,
Consider the following flow graph.
File Source ------->Throttle --------> Packet Encoder -------> Packet
Decoder --------->File Sink 2
\
\---------------> File Sink 1
If the File Source loads a small-size image (around 50 kB), then the Packet
Decoder works properly and File Sink 2 can open the image. However if the
File Source load a bigger image or video (9 MB, for example), then the File
Sink 2 achieve only more than 1 MB, and it can only display a part of the
image/video. This surprised me.
Then I added a File Sink right after the Packet Encoder (it's called File
Sink 1) to see what happened after the Packet Encoder. If I let the Sample
Rate = 32k, then the File Sink 1 receives more than 9 MB, but the File Sink
2 still receive more than 1 MB. If I let the Sample Rate be faster, 1M or
4M, then both the File Sink 1 and File Sink 2 only get more than 1MB.
I wonder if something related to CPU got out of ability with high Sample
Rate or Packet Encoder - Packet Decoder
Best Regards,
V-L
Van-Ly Nguyen,
Signals and Systems of Laboratory - SSL
Faculty of Electronics and Telecommunications - FET
University of Engineering and Technology - UET
Vietnam National University, Hanoi - VNU
Tel: (+84) 978 819 406
On Wed, Jul 30, 2014 at 9:19 PM, Martin Braun <martin.br...@ettus.com>
wrote:
> On 07/30/2014 04:14 PM, Nguyễn Văn Lý wrote:
> > Thank you Tom,
> >
> > I found a note in documentation of the *Packet Encoder *block** where it
> > declares that the *Packet Encoder* is for use with the gnuradio
> > modulator blocks: GMSK, DPSK, QAM. I don't know why only these modulator
> > blocks are supported, but not some popular things like BPSK or QPSK.
> > Another thing is that my task requires the use of OFDM.
>
> These should also work (they are basically subsets of QAM), but *you*
> have to make sure the absolute phase is correct *before* going into the
> packet decoder.
>
> > Suppose now I have a simple flow graph as below:
> > File Source -------> Packet Encoder -------> Packet Decoder --------->
> > File Sink
> > I wonder what types of file can be loaded and processed properly in the
> > *File Source* block (text, image, or video ...), and the same question
> > for the *File Sink* block :-)
>
> Any file. The packet blocks really don't care about the contents.
>
> M
> >
> > Thank you so much
> > Van-Ly
> >
> >
> > Van-Ly Nguyen,
> > Signals and Systems of Laboratory - SSL
> > Faculty of Electronics and Telecommunications - FET
> > University of Engineering and Technology - UET
> > Vietnam National University, Hanoi - VNU
> >
> > Tel: (+84) 978 819 406
> >
> >
> >
> > On Wed, Jul 30, 2014 at 8:24 PM, Tom Rondeau <t...@trondeau.com
> > <mailto:t...@trondeau.com>> wrote:
> >
> > On Wed, Jul 30, 2014 at 4:44 AM, Nguyễn Văn Lý
> > <lynguyenvan....@gmail.com <mailto:lynguyenvan....@gmail.com>>
> wrote:
> >
> > Hi all,
> >
> > Can anyone tell me what do *Packet Encoder* and *Packet Decoder*
> > blocks do? and it would be great if you can give me some example
> > :-)
> > Thanks in advance
> >
> > Van-Ly
> >
> >
> > These are very simple example blocks to show you how to packetize
> > data. Packet bytes go in, they get wrapped into a packet of a given
> > payload length with a header, access code, and preamble. The header
> > is just a 2x repetition of the payload length (16 bits for each
> > field). Leaving the preamble and access code blank just chooses the
> > defaults.
> >
> > The decoder just looks for the access code with the number of
> > available bits wrong. When it's found, it reads the header to get
> > the payload length, extracts the payload, and outputs the payload.
> >
> > Hope this helps.
> >
> > Tom
> >
> >
> >
> >
> >
> > _______________________________________________
> > Discuss-gnuradio mailing list
> > Discuss-gnuradio@gnu.org
> > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> >
>
>
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