Right, the amplitude of the signal is just the length of the I/Q vector,
which is sqrt(I^2 + Q^2). If the receiver is a little off-frequency,
the I/Q vector rotates (because the phase is constantly changing) but
the amplitude is still just the length of the vector.
Alan N1AL
On 09/09/2017 08:19 PM, K9MA wrote:
Never mind: I think I found the answer:
https://www.tjhsst.edu/~rlatimer/techlab/Gelbpaper04.pdf
(The explanation isn't that clear, but I worked through the trig a bit
more rigorously, and got the same answer.)
Basically, the modulating signal, m, is the square root of the sum of
the squares of I and Q.
So really, all the DSP has to do is a little simple arithmetic.
I should have been able to figure that out.
73,
Scott K9MA
On 9/9/2017 21:19, K9MA wrote:
It's been a long time since I studied signal theory in college, but
I'm curious as to how AM is demodulated in a direct conversion radio
like the KX2/3. (SSB and CW demodulation I understand.) Does anyone
know, or have a reference?
73,
Scott K9MA
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