Our data capture unit (DCU) receives analog voltage signals from the Sensor Interface Unit (SIU) and converts them into measured quantities:

  • Time of arrival (TOA) of the blade for blade tip timing
  • Distance for blade tip clearance
  • Rotor speed of rotation

The DCU can also take an external once per revolution pulse as an input for synchronization with other systems and for recognition of individual blades.


Picture Above: Our smallest data capture unit with a data capture card

The data capture unit consists of the following elements:

  • A National Instrument controller mounted in a PXIe chassis and outfitted with Prime Photonics' proprietary data capture cards. Several chassis sizes are available offering capabilities of 4 to 64 channels.  Using more than 64 channels requires multiple PXIe chassis synchronized together.
  • Ethernet communication with the web server of the SIU to control the lasers and detector channels.
  • FOCISTM software for system setup, data acquisition, and real-time test monitoring
  • Optional BT software for post-processing of blade vibration

 

Digitization and Triggering

Our data capture unit digitizes all input channels simultaneously at a sampling rate of 100 MHz per channel.  Data acquisition is time-stamped and synchronized.

Specific trigger points are calculated in real-time and stored.  Several trigger points on the rise or fall of the signal are available, with a choice of a threshold-based trigger or curve-fitting of the rise and fall knees.  A trigger at the mid-point of the blade passage is also available.

Trigger Points On Blade Passage

Depending on the type of blade, some trigger points give more consistent results than others.  Users can select the trigger that best works for each rotor.

 

Output

Timing features are analyzed from the input signals in real-time and digital tip timing measurement data can be processed using the on-board PC, logged to the hard drive or outputted via Ethernet, serial, or PXI/PXIe bus interfaces.

Software loaded on the DCU allows test monitoring and blade vibration analysis.

 

Product Data Sheet

Data Capture Unit Product Sheet (pdf)