Hello all:
I have read the code of “Schmidl & Cox
synchronisation”.And I
find the code use the plateau detectors.It shows that the code will
output
1 at the middle of the plateau.Why not in the first place of the plateau
instead of in the middle of the plateau?
Thank you very much.
Best regards,
zs
Hi zs,
hm, there’s basically three places (that I know of) that GR uses Schmidl
& Cox:
the ofdm_chanest Channel estimator, the original S&C-based
ofdm_sync_pn.py and the more robustness-optimized version in
ofdm_sync_pnac.py.
I suspect you’re referring to one of the two ofdm_sync_pn*.py , but they
differ a bit in how they deal with the peaks. Thus:
Which implementation are you referring to exactly?
Generally, Schmidl & Cox [1] states that
“The timing metric reaches a plateau […] For the AWGN channel, there
is a window with a length of the guard interval where the metric reaches
a maximum, and the start of the frame can be taken to be anywhere within
this window without a loss in the received SNR.”
Thus, without having really read throu ofdm_sync_pn.py in depth, if
using the original approach, you shouldn’t even care where the plateau
is converted to a 1.
Greetings,
Marcus
[1]
http://scholar.google.de/scholar?cluster=3934179950738780116&hl=en&as_sdt=0,5&as_vis=1
On 11/22/2014 06:01 PM, Marcus M. wrote:
Hi zs,
hm, there’s basically three places (that I know of) that GR uses Schmidl
& Cox:
the ofdm_chanest Channel estimator, the original S&C-based
ofdm_sync_pn.py and the more robustness-optimized version in
ofdm_sync_pnac.py.
I suspect you’re referring to one of the two ofdm_sync_pn*.py , but they
differ a bit in how they deal with the peaks. Thus:
Which implementation are you referring to exactly?
He’s probably referring to plateau_detector_fb.
Generally, Schmidl & Cox [1] states that
“The timing metric reaches a plateau […] For the AWGN channel, there
is a window with a length of the guard interval where the metric reaches
a maximum, and the start of the frame can be taken to be anywhere within
this window without a loss in the received SNR.”
Thus, without having really read throu ofdm_sync_pn.py in depth, if
using the original approach, you shouldn’t even care where the plateau
is converted to a 1.
This. Also, how do you detect plateaus? Have a look at the code. Finding
the middle is easy, but how do you know you’re at the beginning?
M