Synchronous Time Averaging

The information provided is for help with Commtest Instruments products:

• vb instrument

QUESTION

Can the vb instrument perform synchronous time averaging?

ANSWER

Yes. If you are using vb firmware 3.00 or later simply choose Time Synchronous Averaging from the Measurement Menu. The parameters settings listed below will be automatically applied for you.

If you are using a firmware version prior to 3.00 follow the procedure below.

• From the Set Parameters Menu, set the following recording parameters:

  Mode/Domain	Time
  Average type	Linear
  No. of Averages	16 or more (recommended)
  Trigger	Tachometer (you must use a tach sensor)

All other parameters are set as usual for a time recording e.g. No. of Samples and Duration are choosen to suit your frequency region of interest. When setting the No. of Samples and Duration it can be helpful to toggle the Domain back to frequency to see how many lines and what Fmax the resulting FFT spectrum will have.

Tach Mode can be either single or free run as this only applies to Measure Mode.

The resulting time waveform can be transfered to Ascent/MAS VB on your PC and viewed in the frequency domain as a spectrum.

FAQ ID: 11679 Last Reviewed: 02/11/2005