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Chapter 4:
Frequency Response Measurements with Swept Sine
HP 3562A
The
The Swept Sine Preset M easurement
Narrowband Linear Sweep
Introd uction
Low frequency network analysis has traditionally been addressed by a grou p of prod·
different. Rather than use expensive low frequency (
ucts known as frequency response analyzers. Wh ile these products perform the
same measurements as a tu n ed network analyzer, the i nternal operation is qu ite
quency response analyzer performs time domai n i ntegration of the i n put signals to
mathematical l y filter sig nals at very low frequencies. M easurement resu lts are usually
d isplayed as point-by-point n u merical values or on an X·Y plotter.
In many applications, notably closed loop control systems, detailed or fi nal system
evaluation is performed using a frequency response analyzer. During the develop
ment of such systems, when time is a critical factor, i nitial characterizations of the
system are often performed using an
many
FFT
also play an i m portant role in the development process. The HP 3562A com bines al l
of these capabilities i nto a single product.
The HP 3562A Swept Sine Mode
When the Swept S in e measurement mode is activated , the HP 3562A is reconfig ured
as a full-fu nction dc-to-100 kHz frequency response analyzer. Key enhancements
incl ude the bu ilt- i n h i g h resolution vector display, the ability to perform plotti ng opera
tions during a measurement and mass storage of resu lts i n an external disc drive.
Source capabi l ities i nclude increasing or decreasing l i n ear or logarithmic sine
sweeps as wel l as manual control of the sweep. Start and stop frequ encies, as well as
the sweep rate, are also user selectable. I n put chan nel capabilities include user
selectable averag ing and integ ration time; automatic i ntegration and u p-and-down
autorangi ng
systems.
The remai nder of this chapter i ntroduces the full span preset swept sine measu re
ment as wel l as a narrowband l i n ear sweep.
Swept Sine M ode
FFT
analyzers, and typically not fou nd i n frequency response analyzers, can
of
i n put ranges can be activated to enhance testing of h i g h performance
<
1 Hz) tracking filters, a fre
analyzer. The analysis capabilities b u i lt i nto
Frequency Response Measurements with Swept Sine
15
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