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R&S ZVH
Spectrum Analyzer Mode (R&S ZVH-K1)
Configuring Spectrum Measurements
Operating Manual 1309.6946.12 - 09
146
Measuring the Frequency
The R&S ZVH provides a frequency counter. The frequency counter accurately
measures the frequency at the marker position.
When calculating the horizontal position of the marker, the R&S ZVH includes the
current span, center frequency and the frequency of the pixel the marker is on. As the
trace only has 631 pixels, the marker position is just an approximation, especially if the
span is very wide.
With the frequency counter, however, you can get a more accurate result of the
horizontal marker position. If the frequency counter is active, the R&S ZVH stops the
measurement at the marker position for a short time and measures the frequency
using the internal reference frequency.
The accuracy of the results therefore depends only on the accuracy of the internal
reference frequency (TCXO). The frequency counter has a resolution of 0.1 Hz and
therefore provides far more accurate results. Despite the accuracy, the measurement
is still fast (because of a special algorithm for the I/Q baseband signal).
The frequency counter only gives completely accurate readings for sine signals that
are at least 20 dB above the noise floor. If the S/N ratio is less, noise affects the
results.
► Press the MARKER key.
► Press the "Marker Function"
softkey.
► Select the "Frequency Count"
menu item
The R&S ZVH displays the
counted marker. If the frequency
counter is on, the marker symbol
changes from M1 to C.
The resolution with which the frequency is measured depends on your selection.
► Select the desired frequency resolution with “Frequency Count Resolution” menu
item.
“Low” has a resolution of 0.1 Hz, “High” a resolution of 0.1 mHz.
Measuring the Signal Bandwidth
The "n dB Down" marker function places two temporary markers to the left and to the
right of the reference marker and measures the bandwidth between the two temporary
markers. The function therefore is a good way to measure the bandwidth of a signal or
the bandwidth of a filter, for example. The temporary markers are represented as two
vertical lines.
The distance to the reference marker is by default 3 dB below the reference marker.
You can also adjust this value manually. Entering a positive value sets the temporary
markers below the reference marker. If it is, for any reason, not possible to calculate
the frequency spacing, dashes are displayed instead of a value.