REFLECTOR: Odd fuel pressure Problem

[Brian Michalk]

Yeah, that's what I meant, aliasing is probably not your problem.  Just
throwing out ideas.

 Brian Michalk  <http://www.michalk.com>
Life is what you make of it ... never wish you had done something.
Aviator, experimental aircraft builder, motorcyclist, SCUBA diver
musician, home-brewer, entrepreneur and barely single


> -----Original Message-----
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]On
> Behalf Of Scott Derrick
> Sent: Saturday, November 27, 2004 7:46 PM
> To: Velocity Aircraft Owners and Builders list
> Subject: RE: REFLECTOR: Odd fuel pressure Problem
>
>
> Brian,
>
> It is interesting as others have related that they too have
> experienced the
> problem but after running awhile with nary an alert?  I've not
> had an alert
> in 300+ hours?  Then  I get then every time I fly?  Possibly the sensor
> changing over time?
>
> The snubber(restrictor) will reduce, change or possibly  eliminate the
> pulses from the pump and pulse/vibrations transmitted from the engine at
> large into the fuel system.
>
> Scott
>
> At 09:05 AM 11/27/2004, you wrote:
> >This is a digital instrument.  It has a shortcoming that analog gauges do
> >not have; it must sample the signal.  Scott, I'm sure you are
> aware of the
> >Nyquist limit, but others here may not.  Basically Nyquist says that you
> >must sample a signal at twice the highest possible frequency that may be
> >present in the signal you are sampling.  This can be applied to
> noise (for
> >aliasing), and for data resolution, like how many pixels does it take to
> >resolve an object, or how high of a frequency is required to represent
> >something.
> >
> >Anyway, the Vision Micro must sample the signal, and it should have a
> >bandpass filter before the sampling circuit so that noise over a certain
> >frequency can't be aliased onto the resulting data.
> >If this is the problem, which doesn't sound like the case here,
> I would look
> >at a couple of things.
> >
> >1) Does the Vision Micro sample the fuel pressure at some rate
> near engine
> >RPM?  Does the fuel pump cause pressure pulses in this range?
> >2) has something changed where the signal line now has spikes on it that
> >possibly change with engine RPM?  This relates to the previous point.
> >3) Has something damaged the bandpass filter?  This one is a bit
> of a reach.
> >
> >  Brian Michalk  <http://www.michalk.com>
> >Life is what you make of it ... never wish you had done something.
> >Aviator, experimental aircraft builder, motorcyclist, SCUBA diver
> >musician, home-brewer, entrepreneur and barely single
> >
> >
> >
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