[ibis-macro] Re: de-convolution in new flow
- From: <fangyi_rao@xxxxxxxxxxx>
- To: <wkatz@xxxxxxxxxx>, <ibis-macro@xxxxxxxxxxxxx>
- Date: Thu, 22 Oct 2009 20:05:22 -0600
Thanks, Walter. So your point is if a RX returns modified impulse in Init and
does not provide GetWave, then you can safely assume RX is LTI and perform
de-convolution.
Fangyi
From: Walter Katz [mailto:wkatz@xxxxxxxxxx]
Sent: Thursday, October 22, 2009 6:47 PM
To: RAO,FANGYI (A-USA,ex1); ibis-macro@xxxxxxxxxxxxx
Subject: RE: [ibis-macro] de-convolution in new flow
Fangyi,
When Rx Init returns a modified impulse response it is telling the EDA tool
that there is an LTI approximation for the Rx. This telling the EDA tool that
this output can be convolved with a digital stimulus pattern to get a time
domain waveform, or it can be run through a statistical analysis such as
StatEye. In either of these two cases a deconvolution is not necessary. The
only times that just hREI(t) (or a deconvolution) is required is when Rx
GetWave does not exist, and either Tx GetWave does exist or one is using an
external waveform at the Rx Pad. So if you are generate an Rx model with an LTI
approximation to a non-LTI Rx (that by the nature of your LTI approximations
does not support deconvolution), then you really should supply an Rx GetWave in
addition to the LTI approximation to the Rx model.
As Kumar suggests in his flows, you can put as input to the Rx Init a channel
that is a Dirac-Delta function, then the out put of the Rx Init function will
be an hREI(t). This technique will work for Rx models that the EDA tool can set
the tap coefficients. But I assume that code in your Rx Init function has some
sort of algorithm which picks an equalization based on the input, and I suspect
you really want the real channel including the real Tx equalization to generate
that input.
The bottom line is that if you have a non LTI Rx, and also want to supply an
LTI approximation (which we think is a good thing) then you also should include
a Rx GetWave call in your model. With the existence of an Rx GetWave, one never
needs to do a deconvolution.
Walter
Walter Katz
303.449-2308
Mobile 720.333-1107
wkatz@xxxxxxxxxx
www.sisoft.com
-----Original Message-----
From: ibis-macro-bounce@xxxxxxxxxxxxx
[mailto:ibis-macro-bounce@xxxxxxxxxxxxx]On Behalf Of fangyi_rao@xxxxxxxxxxx
Sent: Thursday, October 22, 2009 9:05 PM
To: ibis-macro@xxxxxxxxxxxxx
Subject: [ibis-macro] de-convolution in new flow
Hi, Walter;
In this week's meeting we acknowledged the possibility that some model can't
provide an equalizer filter and have to return a modified impulse. This
indicates that the modified impulse is not likely to be the convolution of the
input impulse with a unknown filter. In this case de-convolution in the new
flow won't generate any meaningful result.
Can you provide some clarification?
Thanks and regards,
Fangyi
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