Teledyne LeCroy VirtualProbe - Manual (Page 12)

VirtualProbe Software
Mapping for two-port network specified in two files.
VirtualProbe (XTalk) Crosstalk Block
When the Crosstalk package is present on the oscilloscope, the main VirtualProbe dialog will include the
XTalk block. The block is used to define the S-parameter Touchstone file and port assignments. By using
the XTalk block—and in doing so, including a model of the crosstalk between lanes—you can create a
more accurate model of the circuit and obtain better VirtualProbe results.
The initial implentation of the XTalk block includes the following requirements. If the requirements aren't
met, then warning triangles are shown in the dialog, along with a message in the VirtualProbe Status indi-
cator.
l
The VP Setup should be NumPorts=4, InputType=Channel
l
The Signal Input configuration should match the above requirement, meaning that two data
sources should be provided.
XTalk Dialog Elements
The XTalk dialog includes configuration elements in common with other block types.
B LOCK A CTION
When a block is configured for something other than "Ideal Thru," the left-side of the dialog includes a
set of checkboxes that determine how the circuit element defined by the block is handled. There are
effectively three actions defined by these checkboxes:
Remove effects caused by block checkbox - check this when you want the electrical behavior of the cir-
cuit element to be removed from the signal. This is usually referred to as "De-embedding". Use this set-
ting when wanting to remove the effects of fixtures or interconnects that would otherwise not be in the
path between the transmitter and receiver.
Include effects caused by block checkbox - When not seeking to remove the effects caused by a block,
check "Include effects caused by block." Checking this box enables two more selections that will deter-
mine the block action:
Block is present at time of measurement checkbox - check this when the element was in
the circuit when the measurement was taken, and you wish to include its effects in the out-
put of the virtual probe. That is, you are not seeking to either de-embed or emulate: the
block is a real circuit element, and its effects are to be included in the VirtualProbe output.
Block is NOT present at time of measurement checkbox - check this when wanting to
include the effects of a "virtual channel." This is often referred to as "emulating a channel,"
where the S-parameters of a channel are used to build a transfer function that models the
reflections and loss characterized by the S-parameters. A typical use-case for this selection
10 921148 Rev A