Image:Mains hum spectrum.png

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Mains_hum_spectrum.png‎ (800 × 600 pixel, file size: 6 KB, MIME type: image/png)

[edit] Summary

A spectrum analysis of Mains hum, generated from an uncompressed file thanks to User:Omegatron, using Audacity. Important to note if comparing this to the other spectrum analyses on Colors of noise is that due to the signal having only a single major frequency component (so nearly all of the energy is concentrated in a small frequency band), the intensity scale range was increased by about 50% to show the full peak. Also, the frequency scale was adjusted to include 60Hz and its surrounding frequencies.

[edit] Instructions

Gather spectrum analysis data with Audacity. Run gnuplot on this data with the following script:

set terminal png transparent font "/usr/share/fonts/truetype/ttf-bitstream-vera/Vera.ttf" size 800,600 enhanced
set output "mains_hum_spectrum.png"

# this seems to fix the trailers on the TTF font for the x-label
set bmargin 4

# enable grid
set grid
set grid mxtics

# set up x-axis
set logscale x 10
set xrange [20:22000]
set xlabel "Frequency (Hz)"
set xtics border nomirror

# set up y-axis
set yrange [-40:30]
set ylabel "Intensity (dB)"
set ytics border nomirror

# again to deal with bad bboxes on the TTF...
set key height 1 box

# plot the output from Audacity
plot "mains_hum.txt" title "Mains Hum" with filledcurves x1 3

[edit] Licensing

I, the creator of this work, hereby release it into the public domain. This applies worldwide.
In case this is not legally possible,
I grant any entity the right to use this work for any purpose, without any conditions, unless such conditions are required by law.

File history

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(del) (cur) 06:46, 14 March 2006 . . Ktims (Talk | contribs) . . 800×600 (5,750 bytes) (A spectrum analysis of Mains hum, generated from an uncompressed file thanks to User:Omegatron, using Audacity. Important to note if comparing this to the other spectrum analyses on Colors of noise is that due to the signal having only a singl)
(del) (rev) 06:45, 14 March 2006 . . Ktims (Talk | contribs) . . 800×600 (10,127 bytes) (A spectrum analysis of Mains hum, generated from an uncompressed file thanks to User:Omegatron, using Audacity. Important to note if comparing this to the other spectrum analyses on Colors of noise is that due to the signal having only a singl)
(del) (rev) 06:11, 14 March 2006 . . Ktims (Talk | contribs) . . 800×600 (5,952 bytes) (A spectrum analysis of Mains hum, generated from Audio:Mains_hum_60_Hz.ogg with Audacity. Important to note if comparing this to the other spectrum analyses on Colors of noise is that due to the signal having only a single major frequency comp)