Hi,
I think one point needs to
be clarified. The requirement of delay estimation in calculation of BER needs to
be a deterministic quantity which is required to be set as a parameter. Right?
Now what is the gaurantee that you will get a maxima only at zero shift and not
at any other value? The data is random in nature and could result in max at
other values as well. The maximum value of crosscorrelation will depend on the
sequence of data. Indeed there is a whole field of research going on to give a
maximumum peak only at zero shift and low values at other shifts. As a matter of
fact the BER calculation block works fine if we set the delay higher than the
actual delay but will be erronous if we select the delay to be lesser than the
actual. In the latter case it will be seen that the BER is 50%, since the
reciver is purely guessing.
The link to the MATLAB site
given in the other mail on this same thread addresses the issue very
well.
-Snehamoy
----- Original Message -----
From: Vipperla Ravi Chander N Rao
To: m...@yahoogroups.com
Sent: Friday, October 31, 2003 9:27 AM
Subject: [matlab] Re: Help in Simulink
Hi Hrishikesh, You can find the delay using
crosscorrelation between the Tx signal and received signal. You can
take the samples of tx and rx from simulink to Matlab workspace using the
signal to workspace block. Then you apply cross correlation on the two
signals to calculate the delay between the two.
This is code
given in Matlab help for this purpose: [m,index]=max(xcorr(Rx,Tx)); L=length(Tx); delay=index-L
For more details look into the
MATLAb help on 'Building a frequency shift keying model' under
communications blockset help.
regards, Ravi 200211014, MTech, DA-IICT
>Hai,
> I have developed a Tx - Rx
chain model in simulink in >which i have used buffers, selectors and
some Matlab >Functions.
>Now while calculating the error
rate between Tx data >and the Rx data, how do i calculate the delay tht
the >Tx data needs to be given so tht it can be comapred >with
rx data.
>For eg. if we use 1 buffer of parameter value 12 in >the model, the delay for TX data will be 12 samples, >but the
delay in case of other blocks or concatenaed >buffers is not as
straightforward.
>nybody with any idea on how to take care of the
delay >to be provded or any references.
> Thanks in
advance.
>regards, >hrishikesh V ____________________________________________________________________ "Not
everything that can be counted counts, and not everything that counts can
be counted." -Albert Einstein ____________________________________________________________________
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