# Is Simple Framer and Simple Correllator blocks will synchronize my data?

**URL:** <https://www.ruby-forum.com/t/is-simple-framer-and-simple-correllator-blocks-will-synchronize-my-data/230013>\
**Category:** GNU Radio\
**Created:** [May 27, 2014, 9:04am UTC](https://www.ruby-forum.com/t/is-simple-framer-and-simple-correllator-blocks-will-synchronize-my-data/230013 "2014-05-27T09:04:41Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![jason\_sam](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/7993a0/32.png) [@jason\_sam](https://www.ruby-forum.com/u/jason_sam)\
**Post date:** [May 27, 2014, 9:04am UTC](https://www.ruby-forum.com/t/is-simple-framer-and-simple-correllator-blocks-will-synchronize-my-data/230013/1 "2014-05-27T09:04:41Z")

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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 U.

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**Author:** ![Irfan\_U](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/i/57b2e6/32.png) [@Irfan\_U](https://www.ruby-forum.com/u/Irfan_U)\
**Post date:** [May 27, 2014, 9:53am UTC](https://www.ruby-forum.com/t/is-simple-framer-and-simple-correllator-blocks-will-synchronize-my-data/230013/2 "2014-05-27T09:53:08Z")

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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

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**Author:** ![Irfan\_U](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/i/57b2e6/32.png) [@Irfan\_U](https://www.ruby-forum.com/u/Irfan_U)\
**Post date:** [May 27, 2014, 8:37pm UTC](https://www.ruby-forum.com/t/is-simple-framer-and-simple-correllator-blocks-will-synchronize-my-data/230013/3 "2014-05-27T20:37:17Z")

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On Tue, May 27, 2014 at 3:51 AM, Martin B.  
[removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)wrote:

> 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:

> **[GNU Radio Manual and C++ API Reference:...](https://www.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