Vibration time measurements 1

[delfina]

I would like to take acceleration measurements on a moving vehicle in order to calculate an approriate PSD curve for an evaluation test. Does anyone have any experience in this area? Any good books to get?

Things I am looking for is
1) instrumentation to use
2) how to avoid aliasing, minimise noise and quantitization errors
3) Window to use when converting time data to a PSD
4) Any helpful MATLAB scripts

Thanks
Delfina

 

[Emmet]

We've been involved with several DSP-based data acquisition systems for automotive applications over the past few months. Could you provide more information about your application. Do you want to log data and then evaluate on a PC, real-time. Accuracy requirements ??

Feel free to contact me to disuss adaption of one of the existing systems for your application.

Emmet Raftery
CDA Systems Ltd.

http://www.cdasys.com

(800)280-3972

 

[delfina]

we are using an adxl250eb analog device accel connected to a DATAQ DI-700 data aquisition system. We would like to measure frequecy content up to 200 Hz. We then would like to collect the time data while device is on a car. After that we would like to calculate a psd ( power spectral density ) using octave( like Matlab) from the collected time data.

 

[tomirvine]

I have done similar data collection using battery-powered recording devices from Instrumented Sensor Technology (IST).

Disclaimers:
1. I am not a salesman for IST
2. A number of other vendors offer similar devices

The IST units are available with internal or external accelerometers. The user can specify the anti-aliasing frequency as part of the order. The units are available for sale or rent.

IST also provides post-processing software. I prefer to download the data to ASCII text and use my own program for post-processing, however. This may include shock response spectra and power spectral densities depending on the characteristics of the data.

The P95/50 method can then be used to derive a envelope or test level if a number of power spectral density functions are calculated.

Tom Irvine
Email: tomirvine@aol.com

http://www.vibrationdata.com

 

[electricpete]

See Greg Lolock's FAQ for some good links.

An on-line free textbook which is pretty darned detailed:

http://www.dspguide.com

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