On Tue, 20120110 at 13:39 0500, Bill Fuqua wrote:
> Wait,
> Something is not right here.
> How did you get the baseband envelope?
I generated my square wave approximation in the obvious fashion (sum of
series of sines), then stuffed it through a IIR hilbert transform (and
appropriate delay) to get the I,Q pair, standard phasing method logic.
Baseband envelope is then simply sqrt (I^2 + Q^2), being the magnitude
of the resulting phasor.
Basically I wrote a very simple minded SSB generator in software, had it
write a half dozen data files, then loaded them into gnuplot to produce
the graphs.
You can get something very similar with the following mess:
gnuplot> plot sin(x + pi/2.0) + 1.0/3* sin((3*x)+pi/2.0) + 1.0/5 * sin
((5*x)+pi/2.0) + 1.0/7 * sin ((7*x)+pi/2.0), sqrt((sin(x + pi/2.0) +
1.0/3* sin((3*x)+pi/2.0) + 1.0/5 * sin ((5*x)+pi/2.0) + 1.0/7 * sin
((7*x)+pi/2.0))**2 + (sin(x) + 1.0/3* sin((3*x)) + 1.0/5 * sin ((5*x)) +
1.0/7 * sin ((7*x)))**2),sin(x) + 1.0/3* sin((3*x)) + 1.0/5 * sin
((5*x)) + 1.0/7 * sin ((7*x))
I still say doing it in C was easier, mathcad, matlab, or octave would
also be entirely possible.
Now, what have I misunderstood about SSB?
This has a direct impact on an exciter I am developing, so knowing if
and where I am losing it would be a very good thing.
Regards, Dan.
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