Interesting. I'm crunching Arecobo signals for the SETI project and
their program utilizes FFT.
SETI for those who don't know, is Search for Extraterrestial Intelligence.
Wonder what they'd get if they turned the dish toward Washington?
Dick 75 PB in Atlanta
>
>>
>>Sam
>>
>>I want to start with the basics. What is a FFT analyzer?
>
>FFT stands for Fast Fourier Transform. It's used for many purposes, but one
>of the nice thngs about the FFT is that it can be used to crunch a bunch of
>data and extract the "real" information. Let's suppose that the GMC front
>wheel assembly turns 5 times per second. If noise is being generated by the
>turning, all you need to do is sample the sound (or motion - vibration) at
>a frequency of at least 10 times per second to get valid data. The FFT then
>is used to find out how much energy is present at each frequency (according
>to how the prograsmmer set up the FFT) so that you can determine the
>strongest frequencies generated by the wheel. In practice the sample rate
>is much higher than what I mentioned, but the principles are the same.
>
>By using an accelerometer you can detect minute vibration. There's a lot of
>work that has gone into bearing analysis using vibration analysis. I'm glad
>that Sam has the experience with the frequencies etc.
>
>Sam - what type of accelerometer would we need to instrument the wheels?
>ADI makes some pretty good silicon accelerometers with condictioning
>circuits in teh 5-10g range. I'm pretty certain that I can come up with FFT
>S/W that will run on a PC (or cheap DSP board). (DSP is my primary business).
>
>Henry
>
>We have got to
>>get you and Heinz together. I for one was not bored but I do want to
>>hear your thoughts on why GMC front bearings have such a bad reputation.
>
>"Lots" of failures in the 80s and then the fear of faiulure used as a
>selling tool perhaps?
>
>Henry
>Henry Davis Consulting, Inc / new product consulting
>PO Box 1270 / product readiness reviews
>Soquel, Ca 95073 / IP reviews
>ph: (831) 462-5199 / full service marketing
>fax: (831) 462-5198
>http://www.henry-davis.com/ http://www.henry-davis.com
>
>
their program utilizes FFT.
SETI for those who don't know, is Search for Extraterrestial Intelligence.
Wonder what they'd get if they turned the dish toward Washington?
Dick 75 PB in Atlanta
>
>>
>>Sam
>>
>>I want to start with the basics. What is a FFT analyzer?
>
>FFT stands for Fast Fourier Transform. It's used for many purposes, but one
>of the nice thngs about the FFT is that it can be used to crunch a bunch of
>data and extract the "real" information. Let's suppose that the GMC front
>wheel assembly turns 5 times per second. If noise is being generated by the
>turning, all you need to do is sample the sound (or motion - vibration) at
>a frequency of at least 10 times per second to get valid data. The FFT then
>is used to find out how much energy is present at each frequency (according
>to how the prograsmmer set up the FFT) so that you can determine the
>strongest frequencies generated by the wheel. In practice the sample rate
>is much higher than what I mentioned, but the principles are the same.
>
>By using an accelerometer you can detect minute vibration. There's a lot of
>work that has gone into bearing analysis using vibration analysis. I'm glad
>that Sam has the experience with the frequencies etc.
>
>Sam - what type of accelerometer would we need to instrument the wheels?
>ADI makes some pretty good silicon accelerometers with condictioning
>circuits in teh 5-10g range. I'm pretty certain that I can come up with FFT
>S/W that will run on a PC (or cheap DSP board). (DSP is my primary business).
>
>Henry
>
>We have got to
>>get you and Heinz together. I for one was not bored but I do want to
>>hear your thoughts on why GMC front bearings have such a bad reputation.
>
>"Lots" of failures in the 80s and then the fear of faiulure used as a
>selling tool perhaps?
>
>Henry
>Henry Davis Consulting, Inc / new product consulting
>PO Box 1270 / product readiness reviews
>Soquel, Ca 95073 / IP reviews
>ph: (831) 462-5199 / full service marketing
>fax: (831) 462-5198
>http://www.henry-davis.com/ http://www.henry-davis.com
>
>
