Table of Contents
Advertisement
call and use. It is self contained in that
it has a fully instrumented front-end,
built-in digital zoom, a built-in zoom-
ing signal generator, and a flexible and
user friendly IEC/IEEE interface.
The 2032 is used to measure input-
output and statistical relationships as-
sociated with mechanical, acoustical,
and electrical systems. Its 801 lines
resolution are of special importance
with respect to measurements on me-
chanical systems, since more modes of
vibration can be identified and char-
acterised in a single analysis than with
a conventional 250 or 400 line analyz-
er. Further, it can measure a system
frequency response in two ways, that
is H
1
(=
GAB/GAA)
and H2
(=
Gas/
GsA).
H
1
is best when the output noise
is high, but H 2 is superior when the
input noise is high. Also, measurement
of H 2 tends to reduce the bias error at
resonance peaks. In acoustical sys-
tems, the use of Hilbert Transforms to
compute time
envelope functions
means that the 2032 can measure the
envelope of the system impulse re-
sponse, also known as the "energy-
time curve" from Time Delay Spec-
trometry. Of further importance is the
direct measurement of sound intensi-
ty, in combination with the Brtiel&
Kjrer Sound Intensity Probe Type
3519. Finally, the measurement of fre-
quency responses and signal-to-noise
ratios allows the 2032 to characterise
electrical networks in electronic and
power engineering.
General Description
Introduction
The Dual Channel Signal Analyzer
Type 2032 is a 2-channel FFT analyz-
er which can measure and display 34
different time domain, frequency do-
main, and statistical functions. A com-
plete list of the functions which can be
measured is as follows:
2
Instantaneous Time Function, ch.
A
or ch.
B
Instantaneous Time Function, ch.
A
vs. ch.
B
Enhanced Time Function, ch. A or
ch. B
Enhanced Time Function, ch. A vs.
ch. B
Probability Density, ch. A or ch. B
Probability Distribution, ch. A or
ch.
B
Instantaneous Spectrum, ch. A or
ch. B
Enhanced Spectrum, ch. A or ch. B
Autospectrum, ch. A or ch. B
Cross Spectrum
Frequency Response, H
11
H 2
1/Frequency Response, H
11
H 2
Coherence
Signal-to-noise Ratio
Coherent Output Power
Non-coherent Output Power
Autocorrelation, ch. A or ch. B
Cross Correlation
Impulse Response
Sound Intensity
Cepstrum, ch. A or ch. B
Liftered Spectrum, ch. A or ch. B
These functions are measured via
six different modes of operation,
namely, Single and Dual Channel
Spectrum Averaging, Single and Dual
Channel Spectrum averaging zero pad,
(used to avoid the effects of circular
folding when measuring correlation
functions or impulse responses), Dual
Channel Signal Enhancement, and
Dual Channel Amplitude Probability
mode. The resolution of the 2032 in
the frequency domain is 801 lines,
with a frequency span of from 1,56 Hz
to 25,6 kHz, selectable in a binary se-
quence. The selected frequency span
can then be placed anywhere in the 0
to 25,6kHz baseband frequency range
of the 2032. The real-time frequency
of the 2032 is >5kHz in dual-channel
operation, rising to > 10kHz for single
channel operation.
All functions related to the selected
mode of operation on the 2032 are
continuously available for display,
even while the measurement is taking
place. They can be displayed, (where
relevant), in terms of the real part,
imaginary part, magnitude, phase,
Nyquist plot, (imaginary vs. real), or
Nichols plot, (log. magnitude vs.
phase). The use of Hilbert Transforms
allows the complex time function to be
displayed, and the envelope of the
time function, (the magnitude), to be
calculated. This is of considerable im-
portance when interpreting correla-
tion functions and impulse
resp.
o nses,
Fig.l. Impulse response of a small loud-
speaker shown as the real part (up-
per trace), and the log. magnitude
(lower trace). Only the log. magni-
tude shows the many reflections of
energy taking place
since peaks become much more readi-
ly identifiable in the envelope func-
tion than in the conventionally dis-
played real part, (Fig.1), especially
when the log. magnitude is displayed.
Control of the 2032
The 2032 has been designed for ease
of operation. All control settings rele-
vant to the measurement in progress,
(the "measurement setup"), can be si-
multaneously displayed with the cur-
rent results. The controls are then
accessable via a Field Selector. The
Field Selector is moved to the re-
quired control field, (Fig.2), and a new
setting may be selected either by in-
dexing through those allowed or by
entering it directly as a numerical val-
ue, (for numeric fields, should this val-
ue not correspond with an allowed
control setting, the 2032 rounds it up
or down as appropriate).
At all times, only those fields rele-
vant to the measurement setup are
shown. Some of the control fields are
hidden, to reduce screen clutter.
These fields only become visible when
they are relevant to the measurement
in progress. Also, should an illegal set-
ting be selected in any field, an auto-
matic warning is given by that field
beginning to blink.
The "display setup", which controls
the display of measured results on the
2032 display screen is chosen similarly
to the measurement setup. It controls
precisely what is displayed, (for exam-
ple, frequency response, coherence,
time, etc.), and how it is displayed,
(real part, imaginary part, magnitude,
etc.). It is independent of the mea-
surement setup. Functions can be dis-
played as a half screen display with
the measurement and display setup,
as a full screen display with the dis-
play setup, or simultaneous display of
two independently selectable func-
tions with their display setups, (Fig.3).
Fig.2. The 2032 Field Selector. The selected
field is highlighted on the 2032 dis-
play screen
Advertisement
Table of Contents
