Re: [Discuss-gnuradio] Is Simple Framer and Simple Correllator blocks will synchronize my data?

[Tom Rondeau]

On Tue, May 27, 2014 at 3:51 AM, Martin Braun <address@hidden> wrote:

Hi Irfan,

you can't remove a filter delay.

If all of your sync is working, the packet encoder/decoder is probably what you want to use -- although I think I remember you've tried that before...?
In any case, to get rid of transients, prepend a preamble to your signal. As for the simple_* blocks, I don't think they work well over lossy channels (the packet decoder will allow some slack w.r.t. bit errors).

Cheers,
M

Irfan,

Also check out the correlate_access_code blocks. There are a few different versions of these for different purposes. The tag version might be useful: 

http://gnuradio.org/doc/doxygen/classgr_1_1digital_1_1correlate__access__code__tag__bb.html

And a brand new version that was just checked in last week (documentation on the web isn't updated for this since it's not in a release yet) called correlate_access_code_ff_ts that takes floats in, finds the access code, and produces a tagged stream out. What this means is that the block strips off the access code and creates a stream of just the payload with a tag to mark the start of the payload where the tag holds the payload's length. It uses floats because it expects soft decisions and was designed to work with FEC.

Tom

 

On 27.05.2014 09:03, Irfan Ullah wrote:

Hi all,
I am working on QPSK Transceiver I have done all the synchronization at
receiver except frame delays means frame synchronization is lift. there
are some delays in my recieved data at start I have some garbage values
this delay is due to filters because filters produce one output sample
for N input samples (N filter Taps). I want to remove this delay so
please any one guide me can simple framer and simple correlator will be
used for this purpose? I am currently trying to design my own out of
tree blocks for frame synchronization but if the these two blocks(simple
framer and simple correlator ) are suitable for this purpose or some
modification is required in its code so that I can use it for my purpose.

any help will be much appreciated and may your help will solve my many
problems of this transciever please help me if YOU CAN.

Regards ,
Irfan Ullah

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