fm broadcasting demodulator

[Pablo Gil]

i want to know the advantages and disadvantages of the following FM
broadcasting demodulator:

quadature detector
slope detector
zero crossing detector
PLL

i have chosen PLL for my proyect , and i have to say why. I know that
is the best but i don´t know why

[Craig Carson]

Pablo Gil wrote:

PLL stands for Phase Locked Loop - it is not a demodulator. You would use
a PLL type system where you want to keep tight control over frequency.

Craig.

[broadcast]

In article <39ED9F1B...@logica.com>, Craig Carson
<car...@logica.com> writes

Wrong Craig!
Where a PLL in a transmitter has an error voltage that controls your
frequency a PLL in a receiver has an error voltage that becomes your
demodulated audio.

Simplified answer but you get what I am saying.
Scott

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[H.G.]

Pablo:

The PLL to work in your project, you need to have a tracking loop that can
track the highest modulation frequency.
You get the audio directly out of the phase loop error voltage.
This voltage could be low depending on the PLL design.

The slope detector uses the setting of the VFO ( VCO) against the radio
filters slope. to detect the FM as an amplitude variable R.F. signal.

The Zero Crossing detector uses the frequency variation of the signal
crossing the zero point to trigger a time reference integrator to generate
the audio signal.

The Quadrature detector is the most common detector now used by most designs
its simplicity and cost.

There are others that are even much better in linearity ( less distortion )
and higher output capability.

Marrying two methods to generate a much higher level and lower distortion
when price limits are not imposed are as well common ( slow tracking PLL and
quadrature ) plus others methods.

Regards

H.G.

"Pablo Gil" <GS0...@E.iha.dk> wrote in message
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