TRACE softkey places the marker on a new trace. The trace is
selected via a data entry field. Only those traces can be selected which are
visible on the screen in the same window.
Example:
Three traces are presented on the screen. The marker is always on Trace 1
on switching on.
[MKR ->TRACE]
"2" The marker jumps to Trace 2 but remains on the pre-
vious frequency or time.
[MKR ->TRACE]
"3" The marker jumps to Trace 3. '
IEC/IEEE-bus command: CALC:MARK1:TRAC 1
CALC:DELT:TRAC 1
Frequency Measurement with the Frequency Counter
In order to accurately determine the frequency of a signal, R&S ESCI is equipped with a frequency
counter which measures the frequency of the RF signal at the intermediate frequency. Using the meas-
ured IF, R&S ESCI calculates the frequency of the RF input signal by applying the known frequency
conversion factors.
The frequency measurement error depends only upon the accuracy of the frequency standard used
(external or internal reference). Although R&S ESCI always operates synchronously irrespective of the
set span, the frequency counter delivers a more exact result than a measurement performed with a
marker. This is due to the following:
• The marker measures only the position of the pixel on the trace and infers the frequency of the sig-
nal from this value. The trace, however, contains only a limited number of pixels. Depending upon
the selected span, each pixel may contain many measurement values, which therefore limits the
frequency resolution.
• The resolution with which the frequency can be measured is proportional to the measurement time.
For this reason, the bandwidth is normally made as wide as possible and the sweep time as short as
possible. This results in a loss of frequency resolution.
For the measurement with the frequency counter, the sweep is stopped at the reference marker, the
frequency is counted with the desired resolution and then the sweep is allowed to continue.
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