[ibis-macro] Re: de-convolution in new flow
- From: "Walter Katz" <wkatz@xxxxxxxxxx>
- To: <fangyi_rao@xxxxxxxxxxx>, <ibis-macro@xxxxxxxxxxxxx>
- Date: Thu, 22 Oct 2009 23:21:01 -0400
Fangyi,
Yes, with all of the known numerical instabilities of doing deconvolution.
It would definitely be better if we added an option Init_Returns_Filter, so
that model makers can have the option to create an Rx model with Init just
returning hREI(t) when the Rx model does not have a GetWave.
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 10:05 PM
To: wkatz@xxxxxxxxxx; ibis-macro@xxxxxxxxxxxxx
Subject: [ibis-macro] Re: de-convolution in new flow
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
Other related posts:
