Many Thanks for Your suggestions ! Before I post yesterday my question, I experimenting much hours and nights (my XYL damned me ;-). But also Your different answers show me that this simple "problem" is not so clear as it seems...
> Try using only one of your I/Q channels; > for example, take the I channel, and ignore the > Q channel. Then use a simple detector circuit to > demodulate the signal from the carrier. and > ...but I thought that the I and Q signals were identical > except they were out of phase with each other. o for > AM detection you could use either one by itself and the > result would be the same. Firstly I think so too, but practiclay I had no succes (distortions) and > How about envelope detecting both the I and Q signal > independently (perhaps with a simple diode and RC filter) > and them summing the resulting audio signals? Perhaps > not an optimal solution, but it should work. Why not optimal ? > Or you could emulate what Alberto does in the SDRadio > ECCS demodulator where you could have a pair of SSB > demods (one for LSB and one for USB) fed from the IQ > channels. Then sum the audio outputs from the demods. > The gotcha' on that approach is that you need to > assure that you are always in zero beat unless you > don't mind annoying heterodyne whistles in your audio. > This would require some sort of feedback to form a > frequency control loop Very interesting, I look at ECCS demodulator... Theoreticaly I thought this technique some days before, but I dont build it practicaly so far. Its important where I took the I/Q signals. After the QSD or after the Polyphase-Filter befor sum or diff the signal to LSB/USB. > ...compute sqrt(I^2 + Q^2) in hardware, apart from using > a look-up table programmed in a ROM... maybe someone > else will stand up and suggest a simpler way. and > Cordic has been implemented in VHDL, IIRC (Opencores). Yes I know the Cordic algorithm, but my HDR-2005 is analog hardware.... (FST3253, INA 163, NE5532, ..... ) O.K. I think about Your suggestions and goes on my work-bench.... 73 Chris ------------------------ 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/
