[ibis-macro] Re: AMI_Flows_6.pdf for today's ATM teleconference

  • From: ckumar <ckumar@xxxxxxxxxxx>
  • To: <Arpad_Muranyi@xxxxxxxxxx>
  • Date: Wed, 21 Apr 2010 20:49:53 -0700

<DD7A9A95166BF4418C4C1EB2033B6EE20227F23D@xxxxxxxxxxxxxxxxxxxxxxxx>
Message-ID: <5c023dc83727c256d78a8ba0181a9291@xxxxxxxxxxx>
X-Sender: ckumar@xxxxxxxxxxx
User-Agent: RoundCube Webmail/0.3.1
Content-Transfer-Encoding: 8bit
Content-Type: text/plain; charset=UTF-8

I believe Fangyi is pointing out cases where modified (impulse) response
exists, However it is not the result of convolution with a filter

The larger more issue still stands. i.e  the potential of getting two
different results for the same model
On Wed, 21 Apr 2010 20:20:42 -0700, "Muranyi, Arpad"
<Arpad_Muranyi@xxxxxxxxxx> wrote:
> Fangyi,
> 
> I am sorry but I don't quite understand the second half of your
> 1st sentence (after the word "because") because there is some
> problem with English in it and I am not sure what you mean.  
> Please clarify it.
> 
> Regarding the 2nd sentence about assuming that Rx Init modifies
> the input, I am not sure how that makes a difference, since the
> convolution #2 box seems to be there to do that modification in
> case the Init function didn't do it.  (This is also true for
> the Tx Init function and the convolution #1 box).
> 
> The question that we didn't seem to address in the November
> flow is what Init will return when Init_Returns_Impulse is False.
> This is not shown on the drawings and I can't find anything in
> the current spec that says what is returned in that case.
> 
> If it returns what goes into it, then this setting may be a duplicate
> of the Use_Init_Output = False setting, at least as section 2.3
> describes that in the current spec, unless we meant to distinguish
> how the Init Output is passed to the GetWave functions vs. the 
> next Init function, but this is not spelled out in the spec
> either as far as I can tell.
> 
> Or does it mean that it should return nothing (i.e. uninitialized
> memory, or noise)?  Or should it mean that it should return the
> filter only?  (In that case we do not need the new Init_Returns_Filter
> Boolean).  This must be defined because it fells like we have another
> loose end dangling here.
> 
> Regarding de-convolution, I thought the reason we added the
> Init_Returns_Filter Boolean was to eliminate the need for
> de-convolution.  As far as I can tell, according to the November
> flow de-convolution would only be needed with older models
> which do not have the ability to return filter only to the
> EDA tool.  This would hopefully die out as new models come
> into existence and old models fade away.
> 
> Thanks,
> 
> Arpad
> =====================================================================
> 
> -----Original Message-----
> From: fangyi_rao@xxxxxxxxxxx [mailto:fangyi_rao@xxxxxxxxxxx] 
> Sent: Wednesday, April 21, 2010 9:36 PM
> To: Muranyi, Arpad; ibis-macro@xxxxxxxxxxxxx
> Subject: RE: [ibis-macro] Re: AMI_Flows_6.pdf for today's ATM
> teleconference
> 
> Hi, Arpad;
> 
> Moving the Selector to the right side does not save time-domain
> simulation because it makes the modified impulse returned by Rx Init
> based on the modified impulse returned by Tx Init and Tx Use_Init_Output
> is False. Moreover, you can't assume that Rx Init modifies the input
> impulse by convolving it with a filter.
> 
> In my opinion (I pointed out last year) the November flow does not
> really address this issue. It works only if above assumption is true. In
> addition, de-convolution is still required in certain cases in the
> November flow.
> 
> Regards,
> Fangyi
> 
> -----Original Message-----
> From: ibis-macro-bounce@xxxxxxxxxxxxx
> [mailto:ibis-macro-bounce@xxxxxxxxxxxxx] On Behalf Of Muranyi, Arpad
> Sent: Wednesday, April 21, 2010 7:08 PM
> To: ibis-macro@xxxxxxxxxxxxx
> Subject: [ibis-macro] Re: AMI_Flows_6.pdf for today's ATM teleconference
> 
> Fangyi,
> 
> Thanks for your comments.  I agree with your observations.
> 
> In fact this is why Walter was right when he wrote in his 
> recent comment that the Tx Init Output Selector box on my
> latest drawing should be on the right side instead of the
> left side.  That way both statistical and time domain
> simulations would be correct without having to sacrifice
> either one of them over the other.
> 
> The problem is that making that change would deviate from the
> flow in more than just changing the order of steps 4 and 5 as
> described in the existing specification in section 2.3 and it
> would also bring us back to the issue of having to do a 
> deconvolution for certain configurations, which is why it
> was suggested to me to move that selector to the left side a
> week ago.  I am beginning to see why Walter said that the
> entire flow is flawed in the existing specification...
> 
> The more I push and shove the blocks around in this flow diagram,
> the more I feel that the November flow is the right way to go.  It
> seems that we have already figured it all out in the fall how to
> do this right, and no matter how hard we try to be minimalistic
> in fixing the spec, the best way to do it is as described in the
> November flow.
> 
> Thanks,
> 
> Arpad
> ====================================================================
> 
> 
> 
> -----Original Message-----
> From: fangyi_rao@xxxxxxxxxxx [mailto:fangyi_rao@xxxxxxxxxxx] 
> Sent: Wednesday, April 21, 2010 8:32 PM
> To: Muranyi, Arpad; ibis-macro@xxxxxxxxxxxxx
> Subject: RE: [ibis-macro] Re: AMI_Flows_6.pdf for today's ATM
> teleconference
> 
> Hi, Arpad;
> 
> In the current BIRD only section 2.3 defines the control of Tx
> Use_Init_Output on input impulse response to the Rx Init call. The
> excerpt quoted in Walter's email is actually for the control of input
> waveform to the Rx GetWave call. Your flow presented in the last meeting
> is consistent with section 2.3.
> 
> A key difficulty arises from the condition when Tx has GetWave, Tx
> Use_Init_Output is False and Rx Use_Init_Output is True. If the input
> impulse to Rx Init is the original impulse input to Tx Init, then the
> time-domain bit-by-bit simulation is fine but the statistical simulation
> is broken. If the input impulse to Rx Init is the modified impulse
> returned by Tx Init, then the statistical simulation is fine but the
> time-domain simulation is broken. Given the fact that time-domain
> simulation captures more effects of nonlinear models, it seems we should
> give it higher priority over statistical simulation.
> 
> Regards,
> Fangyi
> ---------------------------------------------------------------------
> IBIS Macro website  :  http://www.eda.org/pub/ibis/macromodel_wip/
> IBIS Macro reflector:  //www.freelists.org/list/ibis-macro
> To unsubscribe send an email:
>   To: ibis-macro-request@xxxxxxxxxxxxx
>   Subject: unsubscribe
> 
> ---------------------------------------------------------------------
> IBIS Macro website  :  http://www.eda.org/pub/ibis/macromodel_wip/
> IBIS Macro reflector:  //www.freelists.org/list/ibis-macro
> To unsubscribe send an email:
>   To: ibis-macro-request@xxxxxxxxxxxxx
>   Subject: unsubscribe
---------------------------------------------------------------------
IBIS Macro website  :  http://www.eda.org/pub/ibis/macromodel_wip/
IBIS Macro reflector:  //www.freelists.org/list/ibis-macro
To unsubscribe send an email:
  To: ibis-macro-request@xxxxxxxxxxxxx
  Subject: unsubscribe

Other related posts:

  1. Home
  2. ibis-macro
  3. Archive
  4. 04-2010