Page 6 - Vibrations 3
P. 6
The spectrum analyser shown
on the left (Agilent 35670A)
has multiple inputs to allow
this type of measurement to
be performed.
It also has the option of averaging several spectra.
This is needed with particularly noisy signals.
If there are two common frequencies in the signals,
calculate the phase between them.
_________________________________________
For a phase measurement, need X-Y feature to produce a
Lissajous Figure
The phase between the two
signals is,
= tan −1 ( )
Why is this important?
Measuring distance between vibration source and
detection.
Velocity of sound through steel is 5,130 m/s.
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