Electronic circuit designer

 

I am a retired teachers looking at Voice Stress Analysis as a hbby. I
need a competent circuit designer, professional or amatuer to design
and build a fairly simple test board for me. Naturally, I will be
prepared to pay any reasonable price for this work. In the first
instance, please contact me with a price quote to produce a working
prototype board as follows.

The board would have a European female telephone input socket. The
telephone input signal would be divided into two streams.

1. One stream would be passed through to a short lead terminating in a
male European telephone plug which could be connected to a standard
telephone, so completing a normal telephone line.

2. The second stream would be directed through a lowpass filter with a
fairly sharp cut off frequency of 12 Hz. The dominant frequency
passing though the filter would be displayed on an LED array or bar
which would approximately show the dominant frequency in the 0 to 12
Hz range. The device should be powered by a 9V battery and appropriate
terminals for such a battery should be included.

I am advised that this is not a highly complex circuit for any
competent engineer and would appreciate anyone with the appropriate
skills, advising me of their charge for this service and also letting
me know somethings of their credentials, experience etc.

Eddie Carron

 

On Jun 20, 11:17 am, eddiecar...@btconnect.com wrote:

The circuit is simple; the rechnique is not and is widely laughed at.
Are you hoping to make it a legitimate science?

 

On Jun 20, 12:17 pm, eddiecar...@btconnect.com wrote:

I can't believe this VSA technique would even work well over a
telephone line; if there is any true science to it wouldn't a high
quality audio feed of the human voice allow a better analysis?

 


eddiecar...@btconnect.com wrote:
Andy comments:

   It looks to me like you want a spectrum analyzer with a
frequency range of 0 to 12 hertz, that will give an
instantaneous readout for voice inputs....
(else how would one identify a "dominate frequency"  in
the presence of many other occurring simultaneously ??  )

   Well, if you want to "see"  0.5 hertz, you have to have a
signal there for at least 2 seconds, probly more for any
real accuracy......

    I would suggest an A/D converter to feed into a computer
file, and then process the info digitally.   The LPF could also
be done digitally, and the spectrum analysis would be done
by an FFT......

    I doubt that an analog circuit, which would have very little
flexibility as far as experimenting with frequencies, cutoffs,
analysis, etc,  would end up giving you what you want...

    Your specifications, that is "zero" hertz, need to be
re-thought, however.

   I'm not volunteering to do the job.  But while the requirements
seem very simple to you, once you get into the analysis of
the problem, things may get a lot more complicated......

    Just a suggestion  from an old , retired, design engineer
who did a lot of stuff like that in the past....

           Andy W4OAH  in Eureka, Texas

 

On a sunny day (Wed, 20 Jun 2007 11:17:32 -0700) it happened
eddiecarron@btconnect.com wrote in


I hope you are aware that phone lines do _not_ transmit frequencies lower then
say 300 Hz.
The 0-12Hz modulation is a FM modulation of spectral components _in_ the voice
band.
I suggest you lookup the theory, you missed something here.
For the others: the technique of for example generating 'emotion' is well
established.
I have somewhere a module for my speech synthesiser......
 http://emofilt.sourceforge.net/
 http://tcts.fpms.ac.be/synthesis/mbrola.html

Of course the speech is in the _audible_ band say 300 Hz - up.

Yes (for the others) it is very possible to generate a stressed sound, and in the
same way to detect it.
But I am no expert on this, so I cannot make this.
I would personally start by having a look at the source code of the encoder
module I have.
Then reverse process.
9V battery makes no sense to me either in these days.
OP forget it or get deeper into the theory.