On Apr 25, 2009, at 6:30 PM, Douglas Roberts wrote:
What leads you to suspect that the CPU I/O noise is random? The noise generated by such comes from a chipset that operates at a given frequency, which is powered by an AC source running at another frequency, filtered through a power supply with capacitors, resistors, etc. with their own set of time constant responses...
I had a custom box some years ago built around a Gigabyte GA-7IXE (Slot-A Athlon). I could hear bus noise when using headphones connected to the onboard audio. I listened for periodicity, but based on keystrokes and the various different instructions occurring due to application behavior...it seemed pretty random to me. However, I realize my observation is not empirical. Morse code can *sound* regular when sent by hand, but a computer may have difficulty interpreting continuous waves of slightly different duration which sound "the same" to the human ear.
Nevertheless, the RFI emitted by computers and their components is a subject of near endless fascination.
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