Determine Y of New Coordinate with -6 db/octave Slope on Log Plot

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Discussion Overview

The discussion revolves around determining the y-coordinate on a log plot given an initial coordinate and a specified slope of -6 dB/octave. Participants explore the implications of this slope in terms of dB and its relationship to the x-axis values in a logarithmic scale.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant asks how to determine the new y-coordinate given a slope of -6 dB/octave from an initial coordinate of (10^2, 100).
  • Another participant notes that a slope of -6 dB/octave is equivalent to -20 dB/decade.
  • It is proposed that the second coordinate could be (10^3, 80) based on the slope.
  • Further clarification suggests that if the slope continues to -12, the next coordinate would be (10^4, 40), but this is contested.
  • One participant corrects the previous claim, stating that (10^4, 60 dB) would be the correct value for a -20 dB/decade slope.
  • There is a question raised about the relationship between the slopes, specifically whether -12 dB corresponds to -40 dB/decade.

Areas of Agreement / Disagreement

Participants express differing views on the correct values for the coordinates based on the slopes discussed. There is no consensus on the implications of the -12 slope, leading to ongoing debate.

Contextual Notes

Participants rely on the definitions of slopes in dB and their conversions to dB/decade, but the discussion does not resolve the mathematical steps or assumptions involved in these conversions.

Dustinsfl
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On a log plot in the x axis, if I have a slope of -6 db/octave from 100db, what would be the location of the new coordinate?

So the y-axis is db and the x-axis is in log.

First coordinate is \((10^2, 100)\) then a slope of -6. The second coordinate is \((10^3, ?)\)?

How does one determine the y location?
 
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dwsmith said:
On a log plot in the x axis, if I have a slope of -6 db/octave from 100db, what would be the location of the new coordinate?

So the y-axis is db and the x-axis is in log.

First coordinate is \((10^2, 100)\) then a slope of -6. The second coordinate is \((10^3, ?)\)?

How does one determine the y location?

A slope of - 6 dB/octave is equivalent to a slope of -20 dB/decade...

Kind regards

$\chi$ $\sigma$
 
chisigma said:
A slope of - 6 dB/octave is equivalent to a slope of -20 dB/decade...

Kind regards

$\chi$ $\sigma$

Then \((10^3, 80)\), and if I had a slope of -12 following, it would be \((10^4, 40)\), correct?
 
dwsmith said:
Then \((10^3, 80)\), and if I had a slope of -12 following, it would be \((10^4, 40)\), correct?...

Not exactly... $\displaystyle (10^{3}, 80\ \text{dB})$ is correct and -20 dB\decade means $\displaystyle (10^{4}, 60\ \text{dB})$, $\displaystyle (10^{5}, 40\ \text{dB})$, etc...

Kind regards

$\chi$ $\sigma$
 
chisigma said:
Not exactly... $\displaystyle (10^{3}, 80\ \text{dB})$ is correct and -20 dB\decade means $\displaystyle (10^{4}, 60\ \text{dB})$, $\displaystyle (10^{5}, 40\ \text{dB})$, etc...

Kind regards

$\chi$ $\sigma$

You said -6 is -20 so wouldn't -12 be -40?
 

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