Polytec PSV 300, Руководство по оборудованию

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   
                                                     
     
The oscillator section generates all drive frequencies for operating the o The oscillator section generates all drive frequencies for operating the other ther
subassembli subassemblies in the es in the vibrometer vibrometer. The drive . The drive frequency for the Bragg cell is frequency for the Bragg cell is of of
central importance as it directly determines the optical frequency offset in the central importance as it directly determines the optical frequency offset in the
interferomet
interferometer and thus er and thus the center frequency of the the center frequency of the carrier signal. carrier signal.
The variable mixing frequency f The variable mixing frequency f LO LO is automatically set by the system control is automatically set by the system control
dependent on the dependent on the selected velocity measurement range. selected velocity measurement range.
     
         
Technically it is just about impossible to attain all desirable and realizable Technically it is just about impossible to attain all desirable and realizable
characterist
characteristics of the ics of the velocity decoder in a velocity decoder in a single universal subassembly single universal subassembly. The . The
modular concept of the controller thus permits the use modular concept of the controller thus permits the use of three different of three different
velocity decoders whereby a maximum of two can be installed at the same velocity decoders whereby a maximum of two can be installed at the same
time. The selection of the decoders depends on
time. The selection of the decoders depends on the application. The models the application. The models
available are the OVD-04, OVD-04HF and PLL-DC which feature the following available are the OVD-04, OVD-04HF and PLL-DC which feature the following
characteristics.
characteristics.
  The OVD-04 as a broad The OVD-04 as a broad band decoder is band decoder is suitable universally for almost all suitable universally for almost all
vibrometer applicat vibrometer applications in the frequency range up to 250 ions in the frequency range up to 250 kHz. Four kHz. Four
m me ea as su urre em me en nt t rra an ng ge es s ffrro om m 1 10 0 tto o 1 0 1 00 00 0 c co ov ve er r m mo os st t tte ec ch hn niic ca all
applications with sufficient amplitude resolution. Characteristic is applications with sufficient amplitude resolution. Characteristic is the excellent the excellent
amplitude and phase frequency response with extremely good amplitude amplitude and phase frequency response with extremely good amplitude
flatness up to the highest frequencies. A special feature of
flatness up to the highest frequencies. A special feature of the OVD-04 is the the OVD-04 is the
D DC C c ca ap pa ab biilliitty y o of f tth he e m me ea as su urre em me en nt t rra an ng ge es s 1 12 25 5 a an nd d 1 0 1 00 00 0 . . F Fo orr
detailed information, please request the respective application note. detailed information, please request the respective application note.
    The OVD-04HF is a special version of the OVD-04 which provides an The OVD-04HF is a special version of the OVD-04 which provides an
extended frequency range up to 1.5
extended frequency range up to 1.5 MHz when operating in the measurement MHz when operating in the measurement
rra an ng ge es s 2 25 5 ; ; 1 12 25 5 a an nd d 1 1 0 00 00 0 ..
  The PLL-DC is a The PLL-DC is a decoder which has been decoder which has been specially developed for applications specially developed for applications
at the lower end of the velocity and frequency range of vibrations. It is an at the lower end of the velocity and frequency range of vibrations. It is an
excellent supplement to the broad band decoder OVD-04, as with its three excellent supplement to the broad band decoder OVD-04, as with its three
m
me ea as su urre em me en nt t rra an ng ge es s 1 1 , , 5 5 a an nd d 2 25 5 iit t e ex xtte en nd ds s tth he e a ap pp plliic ca attiio on n
range for low frequencies to cover also very low velocities. The lower range for low frequencies to cover also very low velocities. The lower
frequency limit of the PLL-DC is 0
frequency limit of the PLL-DC is 0 Hz, i.e. there is no amplitude roll-off at very Hz, i.e. there is no amplitude roll-off at very
low frequencies. Thus it is optimally suited for low frequencies. Thus it is optimally suited for vibration measurement vibration measurements over s over
long distances on buildings or other structures with low long distances on buildings or other structures with low resonance resonance
frequencies. frequencies.
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