Tektronix RSA7100 Series, Быстрый старт Руководство пользователя

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Operation
Advanced techniques
This section contains advanced operating techniques.
Set up triggering
The analyzer offers real-time power-level triggers, frequency mask trigger, DPX density, and external triggers. It uses a
trigger event as a reference point in time for the seamless acquisition of the signal. This allows the analyzer to store
both pretrigger and posttrigger information.
To set up triggering, fi rst select the Event (source and trigger type). Next, continue to set other optional trigger settings and
de fi ne speci fi c actions to be taken upon recognition of a trigger event (such as save data, save picture, etc ).
The analyzer has two triggering modes:
Free Run mode.
In Free run mode, the instrument initiates acquisitions without considering any trigger conditions. It
is a fast and easy way to see the signals. Free Run is usually adequate for the Spectrum display unless you need to
specify a particular time at which to collect the data record.
Triggered mode.
In the Triggered mode, the instrument initiates an acquisition when a trigger event is recognized. The
conditions that de fi ne a trigger event depend on the selected trigger source. There are several source selections available
for choosing the signal to monitor for a trigger event. Once you select Triggered mode, you must select the source. The
trigger sources are:
RF Input
External
Internal Time
Trigger type.
If RF Input is the selected Source, then you can set the trigger type. Type speci fi es what type of violation
will de fi ne a trigger event.
Power : This trigger type triggers the analyzer on time-domain signal characteristics. The incoming data is compared to
a user-selected level in dBm. You can select the time-domain bandwidth and trigger on the rising or falling edge. If
the RF input signal crosses the speci
fi ed level (in the direction set by Slope), a trigger event occurs. A trigger event
does not occur if the power level of the signal simply exceeds the level setting; there must be a power level transient
that crosses the speci
fi ed level.
You can also set a Time Quali fi ed trigger , when Power is the selected Type, from the Time Quali fi ed tab.
Frequency Mask : This trigger type allows you to trigger the instrument when a signal in the frequency domain
violates the mask. You can draw a mask to de fi ne the conditions within the real-time bandwidth that will generate the
trigger event. It allows you to trigger on weak signals in the presence of strong signals. This triggering is also useful
for capturing intermittent signals.
DPX Density : This trigger type enables the instrument to capture any signal you can see in the DPX display, including
dif fi cult to see signals hiding beneath other signals that have a higher amplitude or a greater repetition rate. Using the
Trigger On This™ feature, you can draw a box around the area of interest in the graph, set a Density threshold, and the
instrument will trigger when the measured Density exceeds your threshold.
62 RSA7100 Series Quick Start User Manual