Re: algorithms for location versus for frequency?

"Ron N." <rhnlogic@xxxxxxxxx> writes:

But how can the Goertzel algorithm be used to allow one to detect
if a DTMF tone is 5 mS shorter or longer that the spec allows, or
started 5 mS too late for some allowed response time?

A direct appropach would be to set a threshold and say the on time is
when the output of Goertzel is above that threshold and the off time
is when the output falls below. The times that these happen give you
whether it is late, or too short or long.

How does one get the envelope time information as precisely as one
can measure the frequency of the tones?

That's a problem: you can't get amplitude (envelope) information as
accurately as you can get frequency information. The CRLB on the
variance of frequency estimators goes down as N^3 (N = number of
samples); the CLRB on the variance of amplitude estimation goes down
as N^2.

Ciao,

Peter K.

--
"And he sees the vision splendid
of the sunlit plains extended
And at night the wondrous glory of the everlasting stars."


.