[AMPS] Is screen potential important?

[Phil Clements]

> <<  Also, the input signal is a voice.  Since voice
> > >duty-cycle average around 15%,
> >
> >  rich, does the duty cycle (ssb) without processing run 15% on
average as u
> >stated?
>
> On a sustained AHHHH, the duty-cycle is around 35%.  Sentences have
a
> duty-cycle of roughly 15%.  This is why so many ssb amplifiers get
by
> with a fairly small HV transformer.  In order to be able to see
this, one
> needs an oscilloscope to compare the peak v drop across the
plate/anode
> meter shunt R with the plate/anode meter reading.

Harvey Fletcher, in his book, "Speech and Hearing in Communications"
states
that the range of intensity of  the speech sounds may vary as much as
35 to 40 db
for an extreme speaker. An average speaker produces a range of 28 db,
and if the
"th" as in "thin" is eliminated, this is reduced to 21 db. If
allowances are made for
those who speak louder than normal and those who speak softer than
normal, the
total range is extended to 56 db.

I think that using human voice to prove or disprove feculence in a
radio system
is a very complicated thing to do. I guess the best answer is to shoot
for "worst
case"  speech  and hope for the best. Certainly there will be as many
splatter
results as there are voices at the mike. I propose that we find
someone classified
as an "extreme speaker" and record his voice saying "Joe took Father's
shoe bench
out."  This will become the new test standard to replace the
two-tones.

(((73)))
Phil, K5PC




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