Using The Time-Gated Spectrum Analyzer Capability Without The Gate Utility; Introducing The Time-Gated Spectrum Analyzer Capability - HP 8590 E-Series User Manual

Using the Time-Gated Spectrum Analyzer Capability Without
the Gate Utility
Note
Option 105 is required to perform this application.
Option 101, fast time domain sweep, is recommended in addition to Option 105,
because it significantly increases the resolution available in the time domain.
With Option 101, sweep times (in zero span) as fast as 20 ps can be used,
otherwise the maximum sweep time is limited to >20 ms.
The measurement procedures in this section explain how to use the time gate capability
without the convenience of the Gate Utility. The Gate Utility provides the user with
simultaneous displays of the frequency and time domain to assist in setting up and
manipulating the time gate. See "Using the Gate Utility To Simplify Time Gated Measurements"
for information about using the Gate Utility. All the Gate Utility keys are listed under the
(SWEEP] key in the key menu in Chapter 8. Descriptions of the different Gate Utility functions
are found in Chapter 7.
This section provides the following information:
Introduces the time-gated spectrum analyzer capability.
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Explains how to use Option 105 to view a pulsed RF signal.
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Explains how to use the self-calibration routines with Option 105.
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Explains how to perform a functional check of Option 105.
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Note
For more information about how to use Option 105 with other types of signals,
see Product Note 8590-2 that is shipped with Option 105. Also, see the
descriptions of individual functions in Chapter 7.

Introducing the Time-Gated Spectrum Analyzer Capability

As the spectrum analyzer takes a measurement sweep, it displays a specific frequency as
it sweeps across the frequency range of the spectrum analyzer. Since signals can vary in
time, the spectrum analyzer can miss an event at one frequency because it is sweeping at a
different frequency when the event occurs. With Option 105, the time-gated spectrum analyzer
capability, the spectrum analyzer can provide a "window" of what is going on with a signal at
any specific time, since a spectrum analyzer with Option 105 has the capability to selectively
acquire data based on an external trigger signal. The "window" represents a periodic timed
event during which data acquisition is enabled.
The following figures demonstrate how the time gate can be used to view a signal. For
example, you could have two signals at the same frequency in alternating time slots so they
can share a common system. You can use an oscilloscope to determine whether there are two
signals (see Figure 4-18). However, you could not use a standard spectrum analyzer since both
signals would contribute to the displayed frequency spectrum. By using the time-gate functions
of Option 105, you can use a spectrum analyzer to mask out one signal at a time and measure
each of the two signals separately (see Figure 4-19).
4-22 Making Measurements