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Chapter 4 159
Making Measurements
Using Baseband I/Q Inputs (Option B7C)
Selecting Baseband I/Q Inputs
Baseband I/Q measurements may be made with “unbalanced” inputs
using either two connectors (I and Q), or with “balanced” inputs using
four connectors (I, Q, I
, and Q). A variety of high and low input
impedances can be selected. This flexibility allows measurements to be
made at a maximum number of diagnostic locations in the transmitter
circuitry.
To use the Baseband I/Q inputs the instrument must be in BasicMode,
or another compatible mode which can utilize the Baseband I/Q input
ports. For modes that support Baseband I/Q, the inputs and
measurement defaults are activated and visible when either
I only, Q
only
, or I/Q is selected for Input Port in the Input menu. For modes which
cannot support Baseband I/Q, the inputs and defaults are absent.
Selecting Baseband I/Q Input Connectors
Option B7C adds a softkey menu that lets you select I/Q inputs. This
menu is located under the
Input/Output front-panel key in the Input
menu. To select an input connector press
Input/Output, Input Port. Select
the desired input connector(s) from the following choices displayed:
•
RF - Press to select the 50 Ω "N" RF connector.
•
I/Q - Select if using 2 connector “unbalanced” or 4 connector
“Balanced” I/Q cabling. Complete your selection by choosing the
appropriate input impedance and connectors in the section
“Selecting Baseband I/Q Inputs” on page 159.
• I Only - Select if using I and/or I
input connectors. Complete your
selection by choosing the appropriate input impedance and
connectors in the section “Selecting Baseband I/Q Input Impedance”
on page 164.
• Q Only - Select if using Q and/or Q
input connectors. Complete your
selection by choosing the appropriate input impedance and
connectors in the section “Selecting Baseband I/Q Input Impedance”
on page 164.
•
50 MHz Ref - Select to view the 50 MHz CW calibration signal (signal
level is approximately -25.0 dBm).