Re: Q about noise in time interval measurement averging

<bill.sloman@xxxxxxxx> wrote in message
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On Apr 9, 7:06 pm, "colin" <colin.ro...@xxxxxxxxxxxxxxxxxx> wrote:
"John Larkin" <jjlar...@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in
message

news:g0pk13d9irs7sj10t7kaj5bq44bkkclavk@xxxxxxxxxx

On 9 Apr 2007 08:44:27 -0700, bill.slo...@xxxxxxxx wrote:
It would help to know what the op is actually trying to
do.

Im not so sure, it would just add to the confusion,
you'd probably have lots more questions ...

It is rare for a newby to tell us all we need to know to let us
produce good answers to their question on the first or second go
round, but their answers do tend to dimish the confusion, rather than
adding to it.

Many of the gurus on this user-group have had a lot of practice at
going from what the customers think they want to what the customers
really needs. Some of us have gotten pretty good at it.

Sorry I dont mean to apear to be shunning your help,
in fact ive asked questions here about many different parts of this project,
but its just that if I tell you much more it wont make a lot of sense with
out telling you a whole lot more,
wich I dont realy wish to get involved in discussing right now cos im not
sure I understand the physics behind this or even agree with it !

I'm not even sure if what im doing is acheivable but then I like a good
challange every now and then.

Ive been into electronics since the early 70s,
although I moved into software as people writing software had an easier job
and were payed 2-3 times as much.
not as interesting perhaps.

however I started by writting device drivers etc,
and telling disbeleiving hardware engineers how to fix any hardware bugs I
found was sometimes amusing.
electronics was delegated to a hobby for some time. Ive ended up being quite
well skilled in numerous fields, although trying to be expert in so many
wich this project requires means I end up using the internet a lot.

Right now ive got to go and get some precision machining done ...


basically the signal is cyclic over a few seconds so any long term change
is
ignored, the phase varies cyclicly over a much longer period which is the
measurement
of interest.

The phase of what relative to what?

Think of it like a chopper stabilised op amp, but applied to a mechanical
system.
The intermediate cyclic rate is just the chopper frequency,
this nulls out any offset of phase error and any change of it over a time
longer than the period.

The resultant signal, after the chopper part is removed by software, is just
the value im measuring.
wich is the response to an input wich is made to vary slowly,
thereby allowing a complex phase relationship to be measured.

Colin =^.^=


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