BRUEL & KJAER 1623 - 1 Introduction and Specifications (Product Data)

FEATURES:
• Battery operated
• Frequency range 2 Hz to
20kHz
• Three selectable filter
bandwidths 6%, 1 2%,
23% (1 /3 Octave)
• Tunable from practically
any periodic signal
• Manual tuning facility
• Filter frequency/tuning
signal frequency ratio
adjustable between 99/1
and 1/99
• Synchronization signals for
level and X-Y recorders
• Wide dynamic range,
>60 dB, with crest factor
capability 4
• Large digital display of
filter centre frequency
• Low-pass noise filter for
tuning signal
USES:
•
Synchronous vibration
analysis of rotating
machinery
• Harmonic analysis of
vibration and
electroacoustic signals
• Filtering of response
signals in vibration testing
set-ups
• Harmonic distortion
measurements on
gramophone pick-ups
19-300
type 1 623
Tracking Filter
Filter Center Frequency
Trigger level Betterv
- - ~ - - ~------~ ------
Recorder
Sync.
~
11',:,// ~
L ___ - - ---------
On
Tracking
Filter
Type
1623
Introduction
The fully portable, battery oper-
ated, Tracking
Filter Type 1 623 is a
narrow bandwidth filter whose cen-
tre frequency automatically locks
onto and follows the fundamental
frequency, or a harmonic, of a peri-
odic
tuning signal originating from,
for example, a tachometer or vibra-
tion transducer . Its small size and
built-in battery power supply make
it
ideal for field operation with the
general purpose Vibration Meter
Type 2511.
When combined with a sound lev-
el
meter, vibration meter, or mea-
suring amplifier, sound, vibration,
and other signals which can be con-
verted to
electrical waveforms, can
be
analyzed as a function of a vari-
able frequency reference signal. As
a typical example, can be quoted
the synchronous vibration analysis
of an engine being run up in speed;
the vibration level measured can be
plotted as a function of engine
speed, and
the development of re-
r Menual Tuning/ Preaet '
e
2 00 Hz 20kH z
2H z 200H z
,---- Tracking Mode ~
Tachm. Filter Nol18
Input Input Manual Filter
sonances excited by the fundamen-
tal rotation frequency and its var-
ious
harmonics can then be stud-
ied.
Filters
Both the tuning signal frequency
and
the filter frequency ranges
cover
2Hz to 20kHz in one range
with automatic tuning. Three con-
stant percentage bandwidth filters
are provided with "white noise"
bandwidths of 6%, 1 2% and 23%
( 1/3 Octave) of the tuned fre-
quency.
Constant percentage band-
width filters give a constant resolu-
tion on a logarithmic frequency
scale and are therefore able to give
a
relatively quick analysis over a
wide frequency range.
The
filter, which has a dynamic
range
of about 70 dB, consists of a
digitally tuned pair of two-pole But-
terworth filters that give good selec-
tivity with an attenuation of
1 2
dB/octave. Characteristic curves
for the filters are shown in Fig .1.