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5.4.3.1 Tracking
generator
5.4.4 Detector
The tracking generator is an internal, high stability and accuracy, 50 Ohm
RF generator ranging from 10 Hz to 50 MHz.
Activating the Tracking On function the generator is always tuned at the
same PMM 9010 measurement frequency and scans the range together
with the receiver. This is the standard way a tracking generator works in all
spectrum analyzers.
If the Tracking On function is disabled, the generator becomes a CW signal
source tuned at the frequency set under the RF OUT Freq window.
As usual, to set a given frequency it is therefore enough to edit the value
with the soft keys and the left an right arrows, confirming the selections
entering the units value (kHz, MHz or GHz).
Pressing 0 as the first figure the decimal dot appears automatically.
In both operating modes (tracking or fixed frequency) the output level can
be set between 60,0 and 90,0 dBµV with 0,1dB steps using the RF OUT
Level button.
If a higher or lower level is needed, the User shall adopt either an external
amplifier or an external attenuator.
The tracking generator is extremely useful for several applications: first of
all it is essential to calibrate the receiver itself thanks to the automatic
internal routines specifically developed to this extent, then it can also be
used to transform the PMM 9010 in a scalar network analyzer, helping a lot
in designing and testing RF filters, active stages and a lot of other circuits.
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 9010 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 9010 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).
Analyzer Mode Operating Instructions
5-5
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