Wording for TxRx connection section
George Penokie
gop at us.ibm.com
Thu Nov 15 06:08:31 PST 2007
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Alvin,
That may be enough. See below for a few comments I have.
Bye for now,
George Penokie
Dept 9A8 030-3 A410
E-Mail: gop at us.ibm.com
Internal: 553-5208
External: 507-253-5208
Alvin.Cox at seagate.com
Sent by: owner-t10 at t10.org
11/14/2007 01:42 PM
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Subject
Wording for TxRx connection section
I have made some changes to the woding of this section to help
implementation and interpretation of cable/backplane specs. Please review
and provide discussion on the reflector or during tomorrow's call.
Alvin Cox
Seagate Technology, LLC
Office 405-381-8067
Cell 405-206-4809
E-Mail alvin.cox at seagate.com
5.3.3.2 TxRx connection characteristics
TxRx connection overview
Each TxRx connection shall support a bit error ratio (BER) that is less
than 10-12 (i.e., fewer than one bit error per 1012 bits). The parameters
specified in this standard support meeting this requirement under all
conditions including the minimum input and output amplitude levels.
A TxRx connection may be constructed from multiple TxRx connection
segments (e.g., backplane, cable, cable, backplane). In such cases, the
individual TxRx connection segment should have loss characteristics less
than the total TxRx connection loss characteristic allowed for the
application. Specifying the loss characteristics for individual TxRx
connection segments is the responsibility of the implementer and is beyond
the scope of this specification. <<GP - Added in a more realistic segment
compination were problems occur into the e.g list in this paragraph.>>
Each TxRx connection segment shall comply with the impedance requirements
detailed in 5.2.6 for the conductive material from which they are formed.
An equalizer network, if present, shall be considered part of the TxRx
connection.
TxRx connections shall be applied only to homogenous ground applications
(e.g., between devices within an enclosure or rack, or between enclosures
interconnected by a common ground return or ground plane).
5.3.3.2.1 1.5 and 3 Gbps applications
Each TxRx connection shall be designed such that its loss characteristics
are less than:
a) the loss of the TCTF test load plus ISI at 3 Gbps (see figure 108 in
5.3.2.3) over the frequency range of 50 MHz to 3 000 MHz; or
b) the loss of the low-loss TCTF test load plus ISI at 3 Gbps (see figure
110 in 5.3.2.4) over the frequency range of 50 MHz to 3 000 MHz, if the
system supports SATA devices using Gen2i levels (see SATA-2) but the
receiver device does not support SATA Gen2i levels through the TCTF test
load.
Each TxRx connection shall meet the delivered signal specifications in
table 58 (see 5.3.7.2).
For external cable assemblies, these electrical requirements are
consistent with using good quality passive cable assemblies constructed
with shielded twinaxial cable with 24 gauge solid wire up to 6 meters in
length if no other TxRx connection segments are included in the TxRx
connection.
5.3.3.2.2 6 Gbps applications
For 6 Gbps applications, the TxRx connection shall support a bit error
ratio (BER) that is less than 10-15 (i.e., fewer than one bit error per 10
15 bits) based on digital communication link simulation results, with data
input from S-parameter measurements of the TxRx connection, the specified
reference transmitter device, and the specified reference receiver device.
Figure 105 illustrates an example circuit for simulation. The specific
simulation program used is beyond the scope of this specification.
Simulations typically do not include all aspects of noise that may degrade
the received signal quality. The support of a BER that is less than 10-15
by simulation should yield an actual BER that is less than 10-12. For
external Mini SAS 4x cable assemblies, these electrical requirements are
consistent with using good quality passive cable assemblies constructed
with shielded twinaxial cable with 24 gauge solid wire up to 10 meters in
length if no other TxRx connection segments are included in the TxRx
connection..
SAS 6 Gbps transceiver devices incorporate enhanced features to allow them
to operate over high-loss TxRx connections. These high-loss TxRx
connections may not be suitable for legacy SAS or 6 Gbps SATA devices.
Care should be used to determine if a SAS device location supports a
legacy SAS or 6 Gbps SATA device (see SATA).
<<GP - The term 'legacy SAS' should be removed. The sentence should be
stated as 'These high-loss TxRx connections may not be suitable for
versions of SAS that comply with prior versions of this standard or 6 Gbps
SATA devices.' and the last sentence should be deleted as it does not give
the reader any useful information. >>
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