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<blockquote data-quote="Mark DeArman" data-source="post: 56164" data-attributes="member: 950">Re: Dual Channel FFTYes I would totally agree with that.Off topic, but pink noise doesn&#039;t have a flat spectrum.&nbsp; Normally an RTA has an internal reference filter for pink noise that makes the spectrum flat after filtering it.Yes I think a lot of terminology is the communication issue on my part.&nbsp; The hypothetical system I&#039;m talking about has an &quot;internal&quot; (in memory) loop back, reference, calibration curve, what ever you want to call it.&nbsp; Like I said, I am pretty sure this is the way it is implemented in EASERA, Sound Check, CLIO and a number of others.&nbsp; My question was whether there were advantages/disadvantages of the dual-channel (burn a hardware input) method over the latter.&nbsp; I have gleaned a few from this discussion so far:1) Differential measurements, Point A to Point B.2) Music source or any source external to the measurement system.3) Timing Issues in Windows or other OS.4) Possibly poor COTS DAQ/soundcard hardware designs.&nbsp; I would still like to see some hard data on this one for a typical setup two channel (single stereo ADC) setup.Thanks,Mark DeArman</blockquote>

[QUOTE="Mark DeArman, post: 56164, member: 950"] Re: Dual Channel FFT Yes I would totally agree with that. Off topic, but pink noise doesn't have a flat spectrum. Normally an RTA has an internal reference filter for pink noise that makes the spectrum flat after filtering it. Yes I think a lot of terminology is the communication issue on my part. The hypothetical system I'm talking about has an "internal" (in memory) loop back, reference, calibration curve, what ever you want to call it. Like I said, I am pretty sure this is the way it is implemented in EASERA, Sound Check, CLIO and a number of others. My question was whether there were advantages/disadvantages of the dual-channel (burn a hardware input) method over the latter. I have gleaned a few from this discussion so far: 1) Differential measurements, Point A to Point B. 2) Music source or any source external to the measurement system. 3) Timing Issues in Windows or other OS. 4) Possibly poor COTS DAQ/soundcard hardware designs. I would still like to see some hard data on this one for a typical setup two channel (single stereo ADC) setup. Thanks, Mark DeArman [/QUOTE]

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