I could not hear a difference on my notebook's poor sound system that would allow me to pick out which was which but I don't think we would hear any anyway on a simple steady-state signal such as this. It's a poor example. Group delay distortion is more discernable on transients and more complex waveforms.
Why do finer multi-driver speaker systems attempt to time-align the drivers? Why do telecommunications systems control group delay on speech channels? Why is group delay controlled in analog television systems, in digital transmission systems? Because it can be a discernible and objectionable distortion if it's large enough and the signal or information is susceptible to it. But group delay does not generate new components in the signal - it just shifts them around in time. New waveform but the component frequencies and amplitudes are unchanged. I agree that the assertion misstates the nature of group delay distortion. Tom VE3MEO ----- Original Message ----- From: i2phd To: [email protected] Sent: Friday, February 02, 2007 7:10 PM Subject: [soft_radio] Re: Tecnical discussion --- In [email protected], "in3otd" <[EMAIL PROTECTED]> wrote: > > Maybe someone on the group who is less programming impaired than me > could synthetically generate an SSB signal demodulated with different > phase shifts to see if the differences can be heard... > > Best regards, > > Claudio, IN3OTD > Claudio, no need to program anything to hear (or to not hear...) the differences between two sounds with components of different phases. I generated with Adobe Audition a sound file with a 800 Hz tone, summed with its second harmonic at 1600 Hz, which had 0 degrees of phase difference at time 0 (arbitrarily chosen). Then I did the same, but now the phase difference at time 0 was 90 degrees. I prepared a simple Web page where it is possible to see the two waveforms (quite different one from the other) and to hear them. To my ears they sound _exactly_ the same. The page is at http://sundry.i2phd.com/phase.html This means that the following assertion probably is not valid : 5) If we put a multiple monochromatic signal in a system with flat response, linear amplitude response and NOT flat group delay, will the signal be distorted ? YES .NEW SIGNALS (DISTORTION )WILL BE CREATED FROM THE GROUP DELAY BEING NOT FLAT ,LIKE WHEN THERE IS ONLY NON LINEAR AMPLITUDE RESPONSE . 73 Alberto I2PHD [Non-text portions of this message have been removed]
