vhl in SAS3_EYEOPENING

Remby Taas rembyt at marvell.com
Wed Oct 30 10:29:48 PDT 2013


Formatted message: <a href="http://www.t10.org/cgi-bin/ac.pl?t=r&f=r1310305_f.htm">HTML-formatted message</a>

Graeme,
Hi, thanks. It may be a good idea to include this discussion in the
SAS3_EYEOPENING script's FAQ, as many had used the script to evaluate SAS3
spec conformance with different assumptions.
thnx,
remby
From: Graeme Boyd [mailto:why at pmcs.com]
Sent: Wednesday, October 30, 2013 9:01 AM
To: Remby Taas
Cc: why at pmcs.com; Newman, Harvey; t10 at t10.org
Subject: RE: vhl in SAS3_EYEOPENING
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> [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<mailto: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<mailto: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<mailto:owner-t10 at t10.org>
[owner-t10 at t10.org<mailto: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<mailto:t10 at t10.org>
Subject: vhl in SAS3_EYEOPENING
* From the T10 Reflector (t10 at t10.org<mailto: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<mailto:majordomo at t10.org>



More information about the T10 mailing list