Manfred Weber
Metra Mess- und Frequenztechnik in Radebeul e.K.
PC Vibration Measurement System VibroMetra

Order values

Order values are frequency-selective vibration values. The frequency of the bandpass filter is measured at the digital input of an M302 / M312. The bandpass filter can also be set at multiples or fractions (orders) of this frequency.
Order values

Signal input

1. Signal input
Selects the physical input and the gain of the USB device for the analog signal and the digital input for frequency measurement.

Measurand and unit

2. Measurand and unit
The connected sensor determines the available options. Velocity and displacement are calculated from acceleration by integration (VM-REC+ only).


3. Characteristic
After passing the bandpass filters a sine-wave signal will remain. The following characteristics can be measured to characterize it:
Peak value
Root mean square value
Phase angle
Phase shift between the sine-wave magnitude and the  low-high slope of the digital rpm signal


4. Order
Selects multiples or fractions of the rotation frequency for bandpass filtering.
Rotation frequency
  1 : 1
Triple rotation frequency
  3 : 1
Half rotation frequency
  1 : 2
13/5 rotation frequency
13 : 5

Minimum speed

5. Minimum speed
The M312 is capable of detecting down to  6 1/min. However, it may take up to 10 seconds to detect  standstill. To shorten this detection time you may increase the minimum speed value. For example at  30 1/min detection will be finished after 2 second. Frequencies below 30 1/min will then be suppressed.

Suppress noise

6. Suppress noise
An additional filter can be used to suppress interfering signals apart from the rotation frequency. In the selection field the bandwidth of the filter can be specified or the filter can be switched off.