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Design >> High-Speed I/O Design >> What is precursor ISI?
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Message started by ywguo on Nov 19^th, 2012, 6:03am

Title: What is precursor ISI?
Post by ywguo on Nov 19^th, 2012, 6:03am

Hi Guys,

I know that ISI is inter-symbol interference. But could you please tell me what precursor ISI is? Please have a look at page 13 in the linked slides.
http://www.ece.tamu.edu/~spalermo/ecen689/lecture7_ee689_eq_intro_txeq.pdf

Best Regards,
Yawei

Title: Re: What is precursor ISI?
Post by raja.cedt on Nov 19^th, 2012, 7:40am

hello,
ISI can be thought of as the effect of past and future symbols on the
current symbol. We call previous bit effect as post-cursor ISI and next bit effect pre-cursor.

In case of DFE, we are correcting present bit with knowledge of previously sampled bit which is sampled already. So with this idea we can correct for post cursor ISI, but we don't know abut next bit so DFE can't correct pre-cursor ISI.

Hope i didn't confuse you.

Thanks,
Raj.

Title: Re: What is precursor ISI?
Post by ywguo on Nov 20^th, 2012, 3:21am

Thank you, Raj.