Description

Ultrasonic vibration measurement system

OPVIB is vibrometer used to study vibrations occurring in many areas of life - in the diagnosis of drives of machinery or measurements of vibration impacting on humans and the vibration, the source of which is a man.

 

The device provides a non-contact vibration measurement that does not affect at the tested object.

The instrument is used in the research of components of engines , pumps, gears, bearings, fans and other rotating machinery.

Advanced software of vibrometer enables a quick and convenient signal processing.

Features:

OPVibr was created to measure vibration – its frequency and amplitude. The device generates continuous wave with constant amplitude and frequency on analyzed, vibrating surface using piezoelectric transducer. Reflected wave has modulated frequency and phase – deviation of frequency and phase contains information about movement of analyzed object. This signal is received by another, isolated transducer and then, OPVibr amplifies and demodulates it.

There are two ways of wave modulation:

- Doppler effect: When acoustic wave (carrier) approaches to the vibrating element, it can be perceived like harmonically moving sound source.

- Periodic changes of signal phase induced by position change of reflecting surface.

Demodulation is based on comparison of generated and received waves. Identical center-frequency of wave is achieved by using same, stable time base. It also makes measurement precision independent from absolute value of frequency – only jitter is significant.

 

 

Technical data

The frequency range of transmitted wave: 30kHz-800kHz
The amplitude of the transmitted wave: max. 70Vpp
Output voltage range: 0-5V
The frequency range of vibration: 1Hz - 30kHz
The minimum measurable amplitude of the vibration: <1μm pp
Power supply 12VDC, 0.5A

Data acquisition system

OPVibe contains analog output 0...5 V; demodulated signal can be observed using standard oscilloscopes. Fourier transformation (DFT) and digital filtration can be very useful in signal analysis. DFT significantly facilitates measurement of vibration frequency, existence of harmonics and amplitude of signal with high level of noise. Digital filtering helps in dealing with noise in signal.

In current version of system, oscilloscope USB PICOSCOPE 2204A-D2 produced by Pico Technology was used. It has two input channels and signal generator.

Crucial parameters of this oscilloscope are (recommended values are listed in brackets)

- Analog bandwidth 10MHz (>50kHz)
- Sampling rate 100Msps (>300ksps)
- High input impedance (>100kΩ)
- Up to 12bit resolution (>8bit) 

Detailed information about to oscilloscope and its' software can be found on producers' web site: Pico technologyProducer provides controlling software for PC with oscilloscope. 

Description of Input/Output (IO), functional blocks of device

 

- Output of continuous wave transmitter,
- Output of demodulated signal,
- Input of receiver transducer,
- Input for external clock (optional)

 

Additionally, our device is equipped with high-voltage converter – the circuit requires only one supply voltage. OPVibr also has built-in quartz based clock, which guarantees stable time base.