Hi Alberto, Thanks for the quick reply. I am using a desktop so hopefully my 'line in" input is a true stereo one, I will check that. The culprit may be the SDR reciver board too, I will measure the I/Q output to soundcard. Thanks again for the clarification!! 73 de DJ/NM3R
----- Original Message ---- From: i2phd <[EMAIL PROTECTED]> To: [email protected] Sent: Tuesday, March 13, 2007 2:32:28 PM Subject: [soft_radio] Re: Winrad question --- In [EMAIL PROTECTED] ups.com, "D. J. Wang" <[EMAIL PROTECTED] > wrote: > > I notice instead of getting the full 48KHz bandwidth I was getting > only 24 KHz -i.e., right side of the spectrum is just a mirror image > of the left side. Identical signal can be seen at both +F and -F > position relative to center of the spectral window. I though using > this I/Q detection you can differentiate positive from negative > frequencies (relative to frequency zero), am I wrong? > Thanks! > > de D.J. /NM3R D.J. no, you are not wrong. You should see a spectrum differentiated in its negative part from the positive one. If you don't, then that means that you are not feeding Winrad with a correct couple of I/Q signals. Either one of them is missing, or the two are equal. Are you perhaps using a laptop ? Many today's laptop do not have a true line stereo input, but just a microphone input, which is mono, and in this case just one signal reaches the ADC on the sound chip. Or, if you use a true stereo input, check the connectors and the cables, and possibly the PCB board. If you have a dual trace oscilloscope, look at the I/Q signals in chopped (not alternate) mode, so to have a feeling of their phase relationship and their amplitudes. Check if one of them is much lower in amplitude than the other. Those are the most probable causes of what you are observing. 73 Alberto I2PHD ____________________________________________________________________________________ Never miss an email again! Yahoo! Toolbar alerts you the instant new Mail arrives. http://tools.search.yahoo.com/toolbar/features/mail/ [Non-text portions of this message have been removed]
