[SI-LIST] R: LVDS Transmission Problem
- From: "Guasti Giovanni" <Giovanni.Guasti@xxxxxxxxxx>
- To: <bduzgun@xxxxxxxxxxxxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
- Date: Tue, 27 Sep 2005 14:53:52 +0200
I think LVDS is not the first choice for a so long path.
How is the measured signal? Is a problem of losses, reflections or a =
signal polarization due to distributed capacitance?
maybe the LVDS suffers the high capacity of the system (maybe is just =
the shield).
After the signal measurement, I would try with these:
1)a scrambled (or a more balanced number of '1' and '0')signal=20
2)a unshielded cable / unshilded and shorter cable.
3)replace LVDS with a LVPECL or MLVDS/BLVDS
I hope this could help you,
Giovanni
Hi=20
=20
We have a system which is build up two subsytem. Data signals between =
the
subsystems are in LVDS format. Between these two subsystems there is 10m
cable. LVDS data signals are carried using shielded twisted pair cables.
Inside these two subsystem LVDS signals also passed through backplanes =
and
flexes . We use national LVDS transmitter and receiver. (DS90LV032ATM &
DS90LV031ATM) . The data rate of the LVDS signals are 34MHz. The problem =
is
for some data patterns the transmitted and received data is not same? =
As
the cable length is shortened to 3m and frequency of LVDS signals is
reduced the problem somewhat lowered but we have still the problem. What
could be the reasons for this problem?
=20
<mailto:r@xxxxxxxxxxxxxxxxxxx>=20
M.Baris DUZGUN
Hardware Senior Expert Engineer
ASELSAN INC. MGEO Division
P.K. 30 06011
Etlik ANKARA
TURKEY
Tel : +90 312 847 53 00 / 4534
Fax : +90 312 847 53 20
e-mail : bduzgun@xxxxxxxxxxxxxxxxxxx =
<mailto:bduzgunr@xxxxxxxxxxxxxxxxxxx>=20
=20
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<p class=3D3DMsoNormal><font size=3D3D2 face=3D3DArial><span =3D
style=3D3D'font-size:10.0pt;
font-family:Arial'>Hi <o:p></o:p></span></font></p>
<p class=3D3DMsoNormal><font size=3D3D2 face=3D3DArial><span =3D
style=3D3D'font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=3D3DMsoNormal><font size=3D3D2 face=3D3DArial><span =3D
style=3D3D'font-size:10.0pt;
font-family:Arial'>We have a system which is build up two subsytem. Data =
=3D
signals
between the subsystems are in LVDS format. Between these two subsystems =
=3D
there
is 10m cable. LVDS data signals are carried using shielded twisted pair =
=3D
cables.
Inside these two subsystem LVDS signals also passed through backplanes =
=3D
and flexes
. We use national LVDS transmitter and receiver. (DS90LV032ATM &
DS90LV031ATM) . The data rate of the LVDS signals are 34MHz. The problem =
=3D
is for
some data patterns the transmitted and received data is not same? =
=3D
As the cable
length is shortened to 3m and frequency of LVDS signals is reduced the =
=3D
problem
somewhat lowered but we have still the problem. What could be the =3D
reasons for
this problem?<o:p></o:p></span></font></p>
<p class=3D3DMsoNormal><font size=3D3D2 face=3D3DArial><span =3D
style=3D3D'font-size:10.0pt;
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New =3D
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style=3D3D'font-size:12.0pt;color:navy'><a =3D
href=3D3D"mailto:r@xxxxxxxxxxxxxxxxxxx";
title=3D3D"mailto:serdar@xxxxxxxxxxxxxxxxxxx";></a><o:p></o:p></span></fon=
t>=3D
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style=3D3D'font-size:12.0pt;color:navy'>M.Baris =3D
DUZGUN<o:p></o:p></span></font></p>
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New =3D
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style=3D3D'font-size:12.0pt;color:navy'>Hardware Senior =3D
Expert Engineer<o:p></o:p></span></font></p>
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Division<o:p></o:p></span></font></p>
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06011<o:p></o:p></span></font></p>
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ANKARA<o:p></o:p></span></font></p>
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style=3D3D'font-size:12.0pt;color:navy'>TURKEY<o:p></o:p></span></font></=
p>=3D
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New =3D
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