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DaveSeddon4-Participant
4-Participant
Dec 15, 2022 2:50 PM UTC
Question

Custom Unit Definition

Does anyone know if it is possible to create a unit for optical power loss in optical fiber communications having the units of dB/km?  Thanks in advance for any assistance.

5 replies

terryhendicott
terryhendicott21-Topaz II
21-Topaz II
Dec 15, 2022 6:57 PM UTC

Hi Dave,

Enclosed is a sheet that relates dB linear scale to logarithmic sound intensity in watts/m2

It is possible to use the inbuilt watt and m units then change to decibels or visa versa.

 

 

 

Cheers

Terry

 

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LucMeekes23-Emerald V
23-Emerald V
Dec 15, 2022 9:08 PM UTC

It is possible to define dB as a unit, simply define it as:

LucMeekes_0-1671138096018.png

since dB is in essence unitless. This is what happens upon use:

LucMeekes_1-1671138135456.png

LucMeekes_2-1671138145489.png

LucMeekes_3-1671138166589.png

LucMeekes_4-1671138177315.png

There's no way to know that 1 means dB, as it could also be an angle {  sin(1) }, or any ratio.

But you can put dB in the placeholder for the unit at the result, to get:

LucMeekes_5-1671138457337.png

Drawback is that you have to do that for every result.

 

Success!
Luc

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ValeryOchkov24-Ruby IV
24-Ruby IV
Dec 18, 2022 1:58 PM UTC

dB := 1 - OK

dB+dB=2  It is not OK 

 

The decibel (symbol: dB) is a relative unit of measurement equal to one tenth of a bel (B). It expresses the ratio of two values of...

Decibels were invented to simplify manual calculations, calculations on a logarithmic ruler. In calculations with the help of Mathcad or SMat, they are not needed at all!

There is dB in SMath, But what to do with this "unit", no one knows.

ValeryOchkov_0-1671371800217.png

My colleague, a leading expert in the world on the problem of noise suppression at industrial facilities, believes that it is necessary to redo all calculations where decibels are used to conduct its on a computer.

 

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ValeryOchkov24-Ruby IV
24-Ruby IV
Dec 18, 2022 6:28 PM UTC

ValeryOchkov_0-1671388092629.png

 

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