signal integration in correlation

[preethi19]

i wanted to understand what correlation was... i came accross this link **broken link removed**
i could understand the first 4 diagrams... but in the end it was put the signal is integrated and the shape of the signal i cannot understand why it resulted like that... i went through signal integration and got all mathematical explanation.. can someone pls explain to me in simple words what signal integration is

 

[D.A.(Tony)Stewart]

I agree, there is no correlation with the final integral.

 

[albbg]

You have to move the second signal for both positive (like that shown) and negative displacement with respect to the first signal. Each point of the last diagram has the abscissa equal to the starting point of the second signal (displacement) and the ordinata equal to the integral of the product of the two signal (dashed area).

 

[preethi19]

correlation of a digital signal

i was reading a paper wer the preamble detection was based on correlation.. i went through this link **broken link removed**
i can like understand for correlation we need two signals from the above link.... but say we transmit a preamble of 1011010..... so wer r 2 signals here wer like correlation takes place like in the above link.... like der is no second signal right to correlate the above digital preamble signal... also i saw online wer it was put "Preamble Correlation is the correlation between the measured preamble and an ideal preamble." so measured preamble is preamble at the receiver and is ideal preamble the preamble that was originally trasnmitted????
but how can we measure the measured and ideal preamble and wer do we do this correlation... i mean if receiver is able to obtain the ideal preamble to do the correlation that means it was able to receive the original signal right without any problem.. wer exactly does this correlation between ideal and measured happens?? at the receiver or somewhere else...
if this is not correlation then can someone pls explain to me in simple words wat correlation is and wat would be the output correlated preamble signal and how did we get that result.. do we like xor or like wat... like in simple words... i understood from this link https://www.dspguide.com/ch7/3.htm that correlation is just to find our original signal (in this case 1011010) in the received signal.... so how is this done... i mean if we trasnmit a digital signal wont we get the same signal ok maybe with few errors in the bits... but wat is tough in finding the original signal... is it like 1011010 will be received with additional bits even longer than the original sequence like eg 1110110101010... will it happen like this like due to noise and other factors???? pls help me

 

[D.A.(Tony)Stewart]

The correlation is between expected Sync pattern (1st) and actual (2nd), but I don't see the result as accurate from this process.

 

[albbg]

The received signal is affected by noise, so it's not easy to detect the preable. Using the correlation between the input signal and the expecetd preamble (ideal) you will find a correlation peak when the two signals will be aligned. Of course in the real word in some case you could have false positive (spurious peaks) that have to be filtered.

 

[preethi19]

The received signal is affected by noise, so it's not easy to detect the preable. Using the correlation between the input signal and the expecetd preamble (ideal) you will find a correlation peak when the two signals will be aligned. Of course in the real word in some case you could have false positive (spurious peaks) that have to be filtered.

i get the part wer the expected (ideal) preamble signal is compared with the received preamble (ie one affected by noise)... my doubt is does this correlation (like detecting how similar the signals are) take place at the transmitter or receiver.. it cant take place at transmitter... but then how can the receiver already have an ideal preamble.... do we already load a constant ideal preamble value in the receiver section???? also pls one more doubt is i understand correlation is used to identify how similar the received signal is to the ideal preamble.... but wat is the use of this... does it help to determine noise or does it help in determining the correct preamble or for wat purpose this correlation is used??
because i was working on WSN and i'm working on receiver part... my prof told to work on the correlator part so receiver power consumption can be reduced.... how is correlator (just used to see similarity in two signals) help reduce power consumption... pls help

 

[D.A.(Tony)Stewart]

The preamble is hard wired or stored in the receiver. Re-read my posts which already answered in another one of your similar questions