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Sens.
level--- A. V
&
F
1' \ :;,: -o rv:--,
.-unit--,
and the sensitivity values are shown in
Fig.
2.
The charge sensitivity values
can be finely adjusted from the front
panel or via the interface bus.
No.
m
/
s
2
9
mV
/
Unit
I
,,
l]
m
/
s
in
/
s
' ·
u
mm
in
•
pC
/
Unit
Vibration Meter Section
'---Exp.---'
N
lbf
Fig.
1.
Vibration meter LED
display
showing the selected accelerometer charge
sensitivity
The vibration meter is equipped
with a facility that allows the user to
set 9 vibration
levels.
This enables
complex test programmes to be per-
formed (for example tests conforming
to standards IEC 68-2-6 and MIL-
STD-810 C). For instance, the IEC
standard only requires dual parameter
control, but the MIL standard re-
quires a more stringent procedure in-
volving a larger number of cross-overs
and multi-parameter control.
Easy-to-use Front Panel
The field entry system encorporates
a keyboard for direct entry of vibra-
tion test parameters, and a thumb-
wheel for both coarse and fine adjust-
ment of these settings. Each parame-
ter value is shown on the LED display
whenever
the
associated
key
is
pressed.
A front panel set-up sequence
leads the user through the selectable
parameters one at a time in a logical
order. Set-up selection can be simpli-
fied by storing the parameters in 1 of
the 4 front panel memories, ·allowing
instant recall of the required test set-
up.
Further test set-ups can be stored
externally, for example by a digital
tape recorder or desk-top calculator,
and used to set the front panel test
parameters via the IEEE interface
bus.
Signal Generation
The generator section of the instru-
ment provides a digitally controlled
sinusoidal output which sweeps in fre-
quency
between
selectable
limits.
These limits may be chosen within the
frequency range 1Hz to 10kHz. The
minimum selectable frequency band is
0,3 Hz. Linear and logarithmic fre-
quency sweeps are available with se-
lectable sweep rates from 0,001 to
100Hz/s, and 0,001 to 100oct/min re-
spectively. Frequency control may be
either automatic or manual.
.-----
- -
Vibration M eter
- - - - - - . ,
Ext
.
Filter
In
/
Out
Log.
DC Output
·~
@
Volt
age
Input
Signal
Gnd.
Charge
Input
Fig.
2. Preamplifier input connectors and
sensitivity selection
2
Built-in Preamplifier
Inclusion of a charge preamplifier
enables direct connection of acceler-
ometers and force transducers. The vi-
bration meter LED display showing
the selected charge sensitivity can be
seen in
Fig.
1. The charge sensitivity is
selectable at discrete values in the
range 1 to 31,6
pC/ms-
2
for accelerom-
eters, and is 4 pC/N for force trans-
ducers. The charge input is particular-
ly suitable for use with Brtiel & Kjrer
force transducers and
Uni-Gain®
ac-
celerometers.
Any vibration transducer and pre-
amplifier combination can be used
with the controller by connection to
the voltage input. The user can select
either force or acceleration input sem-
sitivity.
The instrument is provided with a
selection of either floating or ground-
ed input for elimination of ground
loops. Connection of transducers is
made via a TNC connector for charge
input and a BNC connector for volt-
age input. The corresponding sockets
c:
.2
iii
Qj
Qi
(.)
(.)
<
Constant
Velocity
(6 dB/Oct)
The measured vibration level can be
continuously monitored on the LED
display at the touch of a key. It can be
displayed on an oscilloscope, measur-
ing amplifier or voltmeter by using the
preamp. output on the front panel.
The Vibration Exciter Control Type
1050 is equipped with a facility for
automatic calculation of the smooth
cross-over frequencies when more than
one vibration level is set. In addition,
the cross-overs may be set directly
which is useful when the required test
programme includes steps in the vi-
bration level. Examples of typical
tests are shown in Figs. 3 and 4.
Constant Acceleration, Velocity,
Displacement and Force
A constant level of vibration excita-
tion can be attained by using a feed-
back signal to the compressor section.
Constant
Acceleration
Cross-overs.
Frequency
851819
Fig. 3.
Multi-parameter test programme
control.
This test
uses
4 pre-set vibration
levels
requiring 3 cross-overs points which are calculated
by
the controller
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