Excuse my ignorance but I need this spelled out for me. I am trying to
come
up with a phase demodulator to effectively perform the opposite function
as
the gr_phase_modulator_fc class. According to the code this is
effectively
doing output=complex(cos(insensitivity), sin(insensitivity)).
Is there a better approach than simply taking the real component of the
output of gr_phase_modulator_fc and then doing:
original_in = arccos(real(output)) / sensitivity
Is there a block that already does this in grc? Thanks!
-Phelps
On 10/05/2011 05:05 PM, Phelps W. wrote:
Is there a block that already does this in grc? Thanks!
-Phelps
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There’s a quadrature demod block that can generally be used to
demodulate both PM and FM signals.
On 03/07/2014 18:41, Bill D. wrote:
Can you explain this a little. I tried that the other night and
couldn’t get it to do anything. I suspect I am setting the bandwidth
incorrectly or something. I tried that pi/200 - 2pi/100 thing.
Hello Bill,
first, I recommend you to address your replies to the mailing list and
not to me directly, you will have much more chances to receive some
useful answer.
Second, your description of the problem you are encountering is not very
explicative and it makes it very hard to guess what it may go wrong in
your application.
However, the bandwidth setting of the PLL block defines at which offset
frequency from the carrier you are trying to track the gain of the
control loop drops below 1. This affects the PLL capture range: you can
assume that the capture range is equal to the bandwidth, but it depends
on the signal to noise ratio as well.
What you want is to have a bandwidth that is as large as possible but
low enough to do not bleach the modulation you are trying to detect. I
have absolutely no idea where the recommendation of the pi/200 value
comes from.
The settings for the PLL blocks in GNU radio use the not very intuitive,
but practical for the implementation, unit of rad/sample. What I do is
to enter formulas that convert value is Hz to rad/sample based on the
sample rate.
Cheers,
Daniele