Tracking
When this box is selected, the probe continually measures the common mode voltage currently present on the inputs of the
probe. Using the measured common mode values the A, B, and CM offsets will be set automatically. When Tracking is
enabled, the A, B, and CM offsets cannot be changed manually.
The tracking function works best when measuring a differential signal. When making single-ended measurements in
Differential Input mode with a browser tip, set the offset voltage control manually so that the tracking mode will be shut off. If
single-ended measurements are made with tracking mode active, the Offset A voltage will likely not be optimum and will be
affected by the duty cycle of the A input signal. The Offset A voltage should be set manually to the center of the A signal
voltage swing.
Termination voltage
For the P77C292MM adapter, the termination voltage adjusts the effective probe DC loading of the 50 Ω input termination.
Use the voltage to minimize the DC loading of the probe input signals. By setting the voltage equal to the DC bias voltage of
the input signal, the probe DC loading is nulled out, as if a DC block was inserted. However, unlike a DC block, the signal
DC voltage is still present at the probe input and might require you to adjust the Offset voltage to move the signal into the
probe input dynamic range. There are some signal measurement applications that benefit from the availability of an
adjustable termination voltage and avoid the need for a pair of bias tees.
The probe A and B termination
voltages are set and stored
independently common for each
of the four input modes. When
using the P77C292MM adapter,
the voltage can be adjusted over
a limited operating range before
reaching an overload condition.If
VTerm Tracking is checked, the
termination voltages are set
automatically.
Basic operation
P7700 Series TriMode™ Probes 22
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