1004
Marker
markers and then press it a second time to view or adjust the x or y marker values).
Counting Off-screen Markers
If the selected marker is off the X-axis the test set can still be tuned to the marker (unless it is outside the
range of the test set), so the count can still be displayed. This means you can see a count for an off-screen
marker even though there may be no valid Y-value for the marker. If the marker frequency is outside the
range of the test set, the display will show three dashes in the count block (---), and not a number is
returned to a SCPI count query.
Delta Marker
When a Delta Marker is selected while Marker Count is on:
If the reference marker is not a fixed marker, the display shows the difference between the count of the
selected marker and the count of the reference marker
If the reference marker is a fixed marker and there is a count stored in the marker (because Marker Count
was on when the marker became a fixed marker), the display shows the difference between the count at
the marker and the count stored in the reference marker.
Marker Count works in zero span as well as in Swept analysis. The test set tunes to the frequency of the
selected marker, which, for active zero span traces, is simply the center frequency of the test set.
Fixed Markers
Fixed markers have a count stored in them that is generally kept fixed and not updated. If a fixed marker
is selected, or used as a reference, the signal at the marker frequency is not counted; rather the stored
count is seen or used as the reference. The count is stored, if Count is on, when the marker becomes fixed
or when, while fixed, the marker is moved by re-zeroing the reference (if it is the reference marker) or
via a peak search (since both of these, by definition, use valid trace data). The count stored in a Fixed
marker is lost if the counter is turned off, if the marker is moved to an inactive trace, or if the marker is
moved by adjusting its x-value.
More Information on "Counter"
When the counter is on, the count (or the delta count) for the selected marker is displayed.
The invalid data indicator (*) will turn on until the completion of the first count.
Marker Count frequency readings are corrected using the Freq Offset function. Note however that
Marker Delta readings are not corrected, as any offset would be applied to both.
In zero span on active traces the counter continues to function, counting any signal near the center
frequency of the test set.
NOTE No signal farther from the marker frequency than the Res BW is seen by the
counter.
The above command turns on or off the frequency counter. If the specified marker number in the
command is not the selected marker, it becomes the selected marker. If the specified marker number is
not on, FCOunt ON sets it to Normal and places it at center of screen on the trace determined by the
Marker Trace rules. Once the marker count is on, it is on for any selected marker, not just for the one