L3 NARDA PMM 9010, User Manual

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PMM 9030 Frequency Extension 10-21
10.11.4.2 Misc Under the Miscellanea functions menu it is possible to activate or exclude
the Preselector filters and also to set the Tracking Generator .
The
Preselector is composed by a group of filters automatically selected
by the PMM 9030 while it is sweeping or anyway measuring. The aim of the
preselector is to reduce the amount of out-of-band energy entering in the
receiver, thus helping a lot in reducing intermodulation problems and similar
undesired behaviors.
In Analyzer mode the preselector is available only if the entire span falls in
one filter band (see the main specification in chapter 1 to verify the
frequency bands). In this situation on the display it will be shown:
Preselector ON. If the span is larger then one filter only, on the display the
symbol *** will appear instead.
It can be set either ON or OFF with the associated button, and normally it
should be always enabled.
On the top left corner of the screen the symbol “Off” or “On” will be
displayed.
Pressing the
RF OUT button the receiver enters the Generator menu.
10.11.4.3 Detector
This menu allows the Operator to select the most appropriate detector for
the test.
In Analyzer mode the Peak, Average and RMS (Root Mean Square)
detectors are available and can be selected via the appropriate button.
Hold time
The Hold Time (expressed in milliseconds) represents the time the receiver
uses to “take a snapshot” of the incoming signal and to measure it with the
chosen detector. When selecting a detector, the default hold time value is
automatically loaded, but in some cases this time is not appropriate, e.g.
when the interference signals have a low repetition rate. In this case the
PMM 9030 sees a high input signal and therefore tries to set the proper
attenuation automatically increasing the value or the input attenuators.
However, when the input attenuation is set the signal is gone, so the
receiver lowers the attenuation, but then a new peak arrives, and so on and
so forth..
On the other hand, if the Hold Time is too high the PMM 9030 cannot
properly follow the signals.
In this situation the Hold Time value should be manually set to find a
correct compromise.
To set the Hold Time to the lowest possible value (this value dynamically
depends from the measurement conditions), enter the figure 0; if a value
lower than the allowed is entered, the lowest possible value is automatically
selected.
The max. Hold Time that can be set is 30 sec (30.000 ms).