Rohde & Schwarz R&S FSP Series, Operating Manual

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Operating Manual 1164.4556.12 - 06 4.41
R&S FSP Instrument Functions
Analyzer Mode
TRACE MATH See following section “Mathematical Functions for Traces” on page 4.48 .
MIN HOLD The MIN HOLD softkey activates the min peak detector. R&S FSP saves for each
sweep the smallest of the previously stored/currently measured values in the trace
memory. The detector is automatically set to
MIN PEAK . In this way, the minimum
value of a signal can be determined over several sweeps.
This function is useful e.g. for making an unmodulated carrier in a composite signal
visible. Noise, interference signals or modulated signals are suppressed by the min
hold function whereas a CW signal is recognized by its constant level.
Pressing the MIN HOLD softkey again clears the trace memory and restarts the min
hold function.
Remote command:
DISP:WIND:TRAC:MODE MINH
HOLD CONT
(ON OFF) The HOLD CONT ON/OFF softkey defines whether the traces in min hold and max
hold mode are reset after some specific parameter changes.
• OFF: The traces are reset after some definite parameter changes (default)
• ON: This mechanism is switched off.
In general, parameter changes require a restart of the measurement before results
are evaluated (e.g. with markers). For those changes that are known to require a
new measurement (e.g. modification of the span), the trace is automatically reset so
that erroneous evaluations of previous results are avoided.
This mechanism can be switched off for those exceptional cases where the
described behavior is unwelcome.
Remote command:
:DISP:WIND:TRAC:MODE:HCON ON|OFF
AVG MODE The AVG MODE softkey selects logarithmic or linear averaging for the logarithmic
level display mode.
At the same time the difference calculation is switched between linear and logarith-
mic in submenu
TRACE MATH .
Remote command:
CALC:MATH:MODE LIN|LOG|POWER
With logarithmic averaging, the dB values of the display voltage are averaged or
substracted from each other with trace mathematical functions. With linear averag-
ing the level values in dB are converted into linear voltages or powers prior to aver-
aging. Voltage or power values are averaged or offset against each other and
reconverted into level values.
For stationary signals the two methods yield the same result.
Logarithmic averaging is recommended if sinewave signals are to be clearly visible
against noise since with this type of averaging noise suppression is improved while
the sinewave signals remain unchanged.
For noise or pseudo-noise signals the positive peak amplitudes are decreased in
logarithmic averaging due the characteristic involved and the negative peak values
are increased relative to the average value. If the distorted amplitude distribution is
averaged, a value is obtained that is smaller than the actual average value. The dif-
ference is -2.5 dB.