"Rosine, Steve" wrote:

I have an idea to propose as an alternative to the audio amp method of knock
detection for those with cockpit PC's.  I intend to use this as diagnostic
tool to determine bearing condition on my original design PSRU (photos and
drawings to follow in a few days).

THe knock sensor output is essentially the same as a microphone, and can be
connected to the microphone input on a PC sound card.  The growth of digital
music means that there are many programs available that can provide a
real-time FFT display of an audio signal.  I have tested a program called
Spectrogram (www.monumental.com/rshorne/gram.html), that seems quite
versatile (and it's FREE!).  It handles stereo sound, so that means two
knock sensors displayed at once.    I have tested this program with a $25
knock sensor for a Caprice (don't know the year) which has a 1/4" NPT
fitting, and the window air conditioner above my computer.  I was impressed
with the clarity of the display and noticable changes in vibration profile
when I changed A/C fan settings.

Attached is an example from the web page of a warbler call....Imagine the
spectrum of the call of the Wankel.

Steve Rosine

Mustang II / 13B

 
The AirCraft Rotary Engine NewsLetter.              Powered by Linux.

http://home.earthlink.net/~rotaryeng/            http://www.linux.org