vhl in SAS3_EYEOPENING

Graeme Boyd why at pmcs.com
Wed Oct 30 09:01:28 PDT 2013


Formatted message: <a href="http://www.t10.org/cgi-bin/ac.pl?t=r&f=r1310304_f.htm">HTML-formatted message</a>

Remby
The script makes the following assumptions:
- All Tx scope captures have the same Tx amplitude
- The first Tx scope capture has NO Tx emphasis
If either of these two assumptions are wrong then the results will
likely also be wrong.
So in order to get all the cases of Table 45, one would need at least 2
SAS3_EYEOPENING runs to be able to find cases where Vhl is not centered
around 0, and do some of post processing of the K0 and V1V2V3 outputs
|from the script.
Graeme
On Thu, 2013-10-24 at 19:52 -0700, Remby Taas wrote:
> Graeme,
> 
> Hi, allow me to confirm... since the current SAS3_EYEOPENING script
> assumes "constant amplitude" the independent coefficient adjustment
> cannot use the same no-eq reference in the script or else results will
> not be accurate, is that correct? and that for independent coefficient
> adjustment the starting no-eq reference amplitude to be used should be
> equivalent in p-p amplitude for those adjustments, is that correct?
> 
>  
> 
> thnx,
> 
> remby
> 
>  
> 
> 
>  
> 
> 
> 
>  
> 
> 
> From: Graeme Boyd [mailto:why at pmcs.com] 
> Sent: Thursday, October 24, 2013 4:45 PM
> To: Remby Taas
> Cc: why at pmcs.com; Newman, Harvey; t10 at t10.org
> Subject: RE: vhl in SAS3_EYEOPENING
> 
> 
> 
>  
> 
> Remby
> 
> The script requires a single Tx amplitude for all Tx data files,
> effectively making K0 the same and thus also assumes |C3|+ C2 + |C1| =
> 1.
> 
> If one allows Tx amplitude to vary, then you would be required to make
> several SAS3_EYEOPENING runs (one per Tx amplitude or K0 setting).
> This means that you would have to manually calculate the v1/v2/v3 &
> Vhl diff's and make sure they are within specs.
> 
> At this time I have no plans on upgrading the SAS3_EYEOPENING script
> to allow for multiple Tx amplitudes (one per measurement file). Note
> that one could write a wrapper script that would call SAS3_EYEOPENING
> multiple times and process the results.
> 
> Graeme
> 
>  
> 
>  
> 
>  
> 
>  
> 
> 
> On Wed, 2013-10-23 at 10:40 -0700, Remby Taas wrote: 
> 
> Graeme,
> 
> Hi, would the script be updated to include the vhl then? 
> 
> also a question... in the current script would the results of v1v2v3
> be correct/accurate for the cases of independent coefficient update?
> (there was no assumption on K0 restriction?)
> 
>  
> 
> 
>	  thnx,
>	  
>	  remby
>	  
>	   
>	  
>	  
>	  
>	   
>	  
>	  From: Newman, Harvey [mailto:Harvey.Newman at lsi.com] 
>	  Sent: Tuesday, October 22, 2013 3:53 PM
>	  To: why at pmcs.com
>	  Cc: Remby Taas; t10 at t10.org
>	  Subject: RE: vhl in SAS3_EYEOPENING
>	  
>	  
>	  
>	   
>	  
>	  Hi Graeme,
>	  
>	   
>	  
>	  Table 45 controls how a transmitter is allowed to be
>	  controlled by a receiver.  Independent coefficient control
>	  including reducing the overall amplitude using C2 is allowed.
>	  In this case there is not the restriction C2 = 1-|C1|-|C3|.
>	  
>	   
>	  
>	  Table48 and Table 49 are controlling the simulation
>	  environment.	In these cases we are being more restrictive. In
>	  Table 48 the amplitude is controlled by K0 = 0.425 giving the
>	  minimum amplitude of 850 mVdpp. This is only the case if we
>	  also impose the restriction C2 = 1-|C1|-|C3|.  In Table 49 the
>	  end to end simulation needs to adjust the equalization but not
>	  reduce the amplitude in much the same was as Table 48.
>	  Therefore both are correct but in different cases.
>	  
>	   
>	  
>	  While receivers are allowed to reduce the amplitude by
>	  adjusting C2 most of the transmitter equalization test
>	  conditions are with amplitude at maximum.
>	  
>	   
>	  
>	  Please let me know if there are any additional open issues.
>	  
>	   
>	  
>	  Regards,
>	  Harvey Newman
>	  
>	  LSI Corporation
>	  
>	  (408) 433-4028
>	  
>	  
>	  
>	   
>	  
>	  From: Graeme Boyd [mailto:why at pmcs.com] 
>	  Sent: Tuesday, October 22, 2013 1:58 PM
>	  To: Newman, Harvey
>	  Cc: why at pmcs.com; Remby Taas; t10 at t10.org
>	  Subject: RE: vhl in SAS3_EYEOPENING
>	  
>	  
>	  
>	   
>	  
>	  Thanks Harvey
>	  
>	  So in looking at the spec more I have an issue:
>	  
>	  Table 45 allows C1, C2 & C3 to be controlled independently
>	  (for example only one of them can be "dec" while the other two
>	  are in a "hold" state)
>	  
>	  Yet the notes in tables 48/49 states: C2 = 1-|C1|-|C3| which
>	  does not allow the coefficients to be independently controlled
>	  (the peak-to-peak voltage is controlled by the K0 gain as
>	  shown in figure 137).
>	  
>	  
>	  Which is correct?
>	  
>	  If "|C1| + C2 + |C3| = 1" is correct, then Vhl should not
>	  change with changing C1/C2/C3 (so for noise, a +/-20mVpp
>	  should be allowed). In which case Vhl would be 2 times K0 as
>	  reported by the script (K0 in the script is in mVpd rather
>	  than mVpp) and table 45 would need to be updated. Further we
>	  may want to add an extra table to bound Vhl when K0 is changed
>	  (incremented/decremented).
>	  
>	  If independent control of C1/C2/C3 is allowed, then figure 137
>	  & Tables 48/49 need to be fixed up, and Vhl becomes much more
>	  complex to extract from the script (have to do multiple runs
>	  with different Tx amplitudes and subtract twice the reported
>	  K0's).
>	  
>	  Graeme
>	  
>	   
>	  
>	   
>	  
>	  
>	  On Mon, 2013-10-21 at 17:11 +0000, Newman, Harvey wrote: 
>	  
>	  Hi Graeme,
>	  
>	   
>	  
>	  The definition of Vhl for SAS-3 is the largest peak to peak
>	  voltage over any 80 UI since this is the defined measurement
>	  interval. It is not intended to include noise on the
>	  measurement so averaging is allowed.
>	  
>	   
>	  
>	  Regards,
>	  Harvey Newman
>	  
>	  LSI Corporation
>	  
>	  (408) 433-4028
>	  
>	   
>	  
>	  From: owner-t10 at t10.org [mailto:owner-t10 at t10.org] On Behalf
>	  Of Graeme Boyd
>	  Sent: Monday, October 21, 2013 8:15 AM
>	  To: Remby Taas
>	  Cc: why at pmcs.com; t10 at t10.org
>	  Subject: RE: vhl in SAS3_EYEOPENING
>	  
>	   
>	  
>	  Remby
>	  
>	  I would need someone (maybe Harvey or Alvin) to clarify the
>	  definiation of Vhl as used within SAS3.
>	  
>	  Graeme
>	  
>	   
>	  
>	   
>	  
>	  
>	  On Fri, 2013-10-18 at 17:59 -0700, Remby Taas wrote: 
>	  
>	  
>	   
>	  Graeme,
>	  Hi, would you have suggestion for the calculation of vhl(as defined
by SAS3 spec) using any script output parameters?  or would the
SAS3_EYEOPENING get updated?
>	   
>	  thnx,
>	  remby
>	   
>	   
>	  -----Original Message-----
>	  From: Graeme Boyd [mailto:Graeme.Boyd at pmcs.com] 
>	  Sent: Friday, October 18, 2013 5:32 PM
>	  To: Remby Taas; t10 at t10.org
>	  Subject: RE: vhl in SAS3_EYEOPENING
>	   
>	  The definition of Vhl from sas3r05g is "the peak-to-peak voltage
measurement in the interval t1 to t1+80T", which I originally thought was the
same thing as "Maximal Peak Low-frequency Amplitude (K0)" as reported by the
script. However the values for Vhl(k+1)-Vhl(k) in table 45 vary between the 3
values (-20 to +20; -40 to -10; +40 to +10) - only the first makes any sense
based on Vhl being the same thing as K0.
>	   
>	  Graeme
>	  ________________________________________
>	  From: owner-t10 at t10.org [owner-t10 at t10.org] on behalf of Remby Taas
[rembyt at marvell.com]
>	  Sent: October-17-13 3:04 PM
>	  To: t10 at t10.org
>	  Subject: vhl in SAS3_EYEOPENING
>	   
>	  * From the T10 Reflector (t10 at t10.org), posted by:
>	  * Remby Taas <rembyt at marvell.com>
>	  *
>	  I'm doing TX-char sim with 3x waveforms(incl. no-eq ref), and I get
the following results...
>	   
>	  TX_FFE_diff =
>	      0.1875   -0.2940	 -0.1066
>	    -31.7138  -33.1855	  2.0598
>	   
>	  K0 =
>	      0.3702
>	      0.3703
>	      0.3699
>	   
>	  V1V2V3_diff =
>	      0.0997	0.0208	 -0.1181
>	    -25.1636  -23.6397	 -0.1779
>	   
>	   
>	  How/Where do I calculate/get the equivalent VHL?
>	   
>	   
>	  The given/resulting V1V2V3 are the SAS3's v1, v2, v3 deltas, but
the vhl is not given for each case.
>	   
>	   
>	   
>	  *
>	  * For T10 Reflector information, send a message with
>	  * 'info t10' (no quotes) in the message body to majordomo at t10.org



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