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
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