/Best Regards,
Isen I-Chun Chao/
On Sat, Nov 29, 2014 at 6:39 AM, Bastian Bloessl <address@hidden
<mailto:address@hidden>> wrote:
On 2014-11-29 12:34, Isen I-Chun Chao wrote:
Okay, I got it.
One more quick question.
I have been pretty confused about what the sync long and sync
short are,
respectively, responsible for?
Sync short is for frame detection and searches for the cyclic
pattern of the short preamble (autocorrelation). Once a (potential)
frame is detected, sync long correlates sync_length samples with the
long preamble and searches for peaks to align OFDM symbols.
Thanks.
/Best Regards,
Isen I-Chun Chao/
On Sat, Nov 29, 2014 at 6:29 AM, Bastian Bloessl
<address@hidden <mailto:address@hidden>
<mailto:address@hidden <mailto:address@hidden>>> wrote:
On 2014-11-29 12:28, Isen I-Chun Chao wrote:
Hi Bastian,
Thanks for your reply.
The peaks you mentioned is like the correlation result?
Yes, exactly
/Best Regards,
Isen I-Chun Chao/
On Sat, Nov 29, 2014 at 6:21 AM, Bastian Bloessl
<address@hidden <mailto:address@hidden>
<mailto:address@hidden <mailto:address@hidden>>
<mailto:address@hidden
<mailto:address@hidden> <mailto:address@hidden
<mailto:address@hidden>>>__> wrote:
Hi Isen,
On 2014-11-29 07:01, Isen I-Chun Chao wrote:
Hi,
I am using gr-ieee-802-11 and putting a custom
block,
which is
responsible for adding a 90-sample preamble at
the head
of incoming
sample stream, right after the output of WiFi
PHY Hier,
as attached
figure, generator.png. So the sample stream is
changed
as attached
figure, adding_preamble.png.
However, in the case of use of
transceiver.grc, I can still
successfully
decode received data, which is keep printing
out "Hello
World!".
Does anyone know why adding extra samples at
the head of
transmission
samples does not affect the receiving results?
Does it
because
somewhere
in Rx side detect the OFDM preamble so the
payload can
be normally
processed without being affecting by the extra
samples
placed before
OFDM preamble?
The sync long block does matched filtering with
the long
preamble
and searches for peaks in a configurable window
(sync length
parameter). Looks like even if you add 90 symbols
the peak
that the
block is looking for is still in the window.
Best,
Bastian
--
Dipl.-Inform. Bastian Bloessl
Distributed Embedded Systems
University of Paderborn, Germany
http://www.ccs-labs.org/~____bloessl/
<http://www.ccs-labs.org/~__bloessl/>
<http://www.ccs-labs.org/~__bloessl/
<http://www.ccs-labs.org/~bloessl/>>
--
Dipl.-Inform. Bastian Bloessl
Distributed Embedded Systems
University of Paderborn, Germany
http://www.ccs-labs.org/~__bloessl/ <http://www.ccs-labs.org/~bloessl/>