3 Spectrum Analyzer Mode
3.2 Swept SA Measurement
The decimal point location is fixed, without trailing zero suppression. It displays in units of Hz. The
digits to the left of the decimal have leading zero suppression. For understandability, with more than 4
digits to the left of the decimal point, the digits are grouped in threes, from the decimal point left, with
spaces between those groups of three. For negative numbers there is no space between the minus
and the number
Examples:
ΔCnt1 –2226.493 Hz
ΔCnt1 –22 226.493 Hz
Backwards
Compatibility
Notes
In some legacy analyzers (for example, 8560 series) the FreqOffset value was applied to the Marker
Count. In others (for example, ESA and PSA) it was not. X-Series follows the ESA/PSA model and does
not apply Freq Offset to the Marker Count
In ESA and PSA, the reference marker for Delta markers was always counted. In X-Series the marker is
counted for Normal and Delta markers; but for the reference marker, if it is a Fixed marker, we use the
count stored in the Fixed marker. This enhanced capability may require a change to some user code
and/or test procedures
Query Count Value (Remote Query Only)
Queries the frequency count. Returns the absolute count, unless the specified
marker is in Delta mode, in which case it returns the relative count. If the marker is
Off, or the marker is on, but the counter is off, the instrument returns Not a Number
(NAN)to a SCPI count query. A marker with no stored count, or a non-Fixed marker
on a stored trace, also returns Not a Number to a SCPI count query. This result may
simply mean that the first sweep after the counter turned on has not yet completed.
Remote Command
:CALCulate:MARKer[1]|2|…|24:FCOunt:X?
Notes Does not cause the specified marker to become selected
Understanding the Marker Counter
Using the internal counter we can count the frequency of a marker, but we cannot
count while we are actually sweeping. So, once we are done with a sweep, we move
to the selected marker frequency and count that frequency. Then, if the marker is a
Delta marker, the count is also taken for its reference marker. The count is actually
performed by moving the LO to the frequency (or frequencies in the case of a Delta
marker) we wish to count. The count is executed on a marker-by-marker basis and
no further count is taken until after the next sweep (even if the marker moves before
another sweep has completed).
The Marker Count is taken by tuning the instrument to the frequency of the marker
and counting the IF, with the instrument not sweeping. The count is adjusted for
display by adding or subtracting it (as appropriate) from the LO frequency, so that
you see a count that represents the signal frequency. This is true even if External
Spectrum Analyzer Mode User's &Programmer's Reference 377
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