[sdiy] QTC and delurk

[Veronica Merryfield]

Hi Neil

I have experience with TDR in a couple of application areas. One thing that 
it could do is pickup playing harmonics as well as 'fretting' the string. 
However, TDR is complex at the best of times and comparatively short 
transmission times make it harder. It is on the bottom of the list.

Yes it is a complex problem with no simple solution. Whilst using QTC does 
have issues, it does have the dangling carrot of sensing position and after 
touch..

Thanks

Veronica

----- Original Message ----- 
From: neil.johnson97 at ntlworld.com
To: Veronica Merryfield
Cc: synth-diy at dropmix.xs4all.nl
Sent: Monday, May 14, 2007 3:10 AM
Subject: Re: Re: [sdiy] QTC and delurk



> > However, a system that has some form of hint scheme that can
> > steer a pitch detector holds much hope - it's very much like giving a 
> > PLL
> an
> > input frequency that is close to where it needs to lock.

If the strings are metallic then perhaps some kind of time domain 
reflectometry (TDR) system to measure the length of the vibrating string 
might provide an accurate input?  In this case the fret board would simply 
be a conductive medium to provide an impedance discontinuity at the point 
the finger is applying pressure to the string.  Note that this technique is 
not easy, but it does make the (electrical) design of the fret board easier.

I get the impression that any solution for this problem is going to be 
complex, the question boils down to where you want the complexity, and where 
you don't want it.

Neil

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