Rohde & Schwarz FSH4, Руководство по эксплуатации

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R&S FSH Spectrum Analyzer Mode
Configuring Spectrum Measurements
Operating Manual 1309.6275.12 - 14 102
M Press the MARKER key.
M Press the "Marker Function"
softkey.
M Select the "Noise" menu item.
The R&S FSH shows the level at
the marker frequency in dBm/Hz. If
you are using a delta marker for
the measurement, the results have
the unit dBc/Hz with marker 1
being the reference.
Measuring the Frequency
The R&S FSH 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 FSH 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 FSH 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.
M Press the MARKER key.
M Press the "Marker Function"
softkey.
M Select the "Frequency Count"
menu item
The R&S FSH displays the
counted marker frequency with a
resolution of 1 Hz. If the frequency
counter is on, the marker symbol
changes from M1 to C.