Operating Instructions
Measurement menu
Use this menu to change units, Vp control, and reflection coefficient calculation method.
Extra long mode
Extra long mode allows the CT100 to take traces out to more than 10000 meters (33000
feet). Extra long is not as usable as other cable length modes, and some features don’t
work properly. It should only be used when necessary. When in extra long mode, the
Cable Length
menu option will change to reflect this. Selecting the cable length button
will switch away from extra long mode.
Set cursor X pos.
Enter in a value for the cursor position and the cursor will move to that position for the
selected trace. On a time domain trace, enter the value in current horizontal units. On
a frequency domain trace, enter the value in MHz.
Fine/coarse Vp control
Enable or disable 6 digit (fine) Vp precision.
Units
Switch between meters and feet for horizontal measurements.
Vert. Ref. menu
This menu has various options for setting and configuring a vertical reference. Vertical
reference uses scans of open and short signals to give improved vertical
measurements. In general, a vertical reference is valid only in the configuration and at
the temperature for which it was created.
Vert. ref. off/on
This menu option will toggle on and off a vertical reference as created using the
Set
Vert. Ref.
option (see below).
Set vert. ref.
This option requires both open and short attachments for the CT100. The CT100
will automatically calculate a vertical reference and prompt for a required open or
short. When a vertical reference is calculated and applied, vertical values — millirho
and Ohms — are much more accurate than standard TDR measurements. The
vertical reference process, however, can take some time to calculate and is only
valid for the temperatures at which it was taken. Vertical references cannot be
stored for use across multiple sessions.
When the setup is complete, a green vertical line will appear under the active cursor.
Points to the right of this line will use the new vertical reference, while points to the
left will use the standard vertical measurements. This is useful for setting up a
vertical reference at the end of a cable that won’t have its impedance changed by an
attached open and short. This will often cause a visible break in the trace.
Vert. ref. center imp.
By default, when vertical reference is on, the center impedance, or impedance at 0
millirho is taken to be 50 Ohms. This option lets you enter in a new value. Use this
Mohr CT100 / CT100HF Operator's Manual
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