Hi Stan, I and Q are not the same. Chris, AM can be written as m(t)=i(t), 0=q(t) with m(t) positive. Equivalently, in passband, m(t)*cos(2pi f t) + 0 * sin (2 pi f t). At baseband, the demodulation is done coherently. You need to adjust the local oscillator until you get nothing at all on the q(t) channel. Two conditions must be kept. The gain such that the magnitude (i(t)&2 + q(t)^2) after passing though a slow envelope detector is a constant non-zero value. Use a feedback loop to adjust the VCO. In the loop, 0V is the reference signal, 0- q(t) the error, and the controlled variable output goes into the the VCO input. This scheme will also demodulate DSB.
Frank >Hopefully I do not show my ignorance but I thought that the >I and Q signals were identical except they were out of phase >with each other. So for AM detection you could use either >one by itself and the result would be the same. ------------------------ Yahoo! Groups Sponsor --------------------~--> Get fast access to your favorite Yahoo! Groups. Make Yahoo! your home page http://us.click.yahoo.com/dpRU5A/wUILAA/yQLSAA/ELTolB/TM --------------------------------------------------------------------~-> Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/soft_radio/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
