Re: [Boost-users] [units] EE Acceleration, Velocity, Displacement in terms of decibels

Subject: Re: [Boost-users] [units] EE Acceleration, Velocity, Displacement in terms of decibels
From: Michael Powell (mwpowellnm_at_[hidden])
Date: 2011-12-04 16:54:01

On Sun, Dec 4, 2011 at 11:35 AM, Matthias Schabel
<boost_at_[hidden]>wrote:

> > Has anyone done any work, conversions, etc, with Acceleration, Velocity,
> Displacement (Length) in terms of decibels? dB, dBA, dBV, etc, and
> conversions to/from more "conventional" units like meters, meters per
> second, meters per second per second?
> >
> > I am learning, for example, that it is possibly to integrate across the
> Time dimension in order to yield Velocity from Acceleration, or similarly,
> Displacement (Length) from Velocity.
> >
> > I am doing a job with these type conversions going on across a spectrum
> analysis and would be interested in hooking up the calculations using
> boost::units to help enforce dimensional / unit integrity.
>
> Decibels and all their variants are defined as logs of ratios and,
> therefore, must be dimensionless. What would be sensible is to define
> various helper functions that take a quantity and return a log ratio.
>

Yessir, that jives with the legacy C/C++ code I am seeing. A lot of
log10(...) and pow(10,...) converting to and from Db and from Acceleration
to Velocity to Displacement and back.

Are there any examples how to construct such a ratio-based conversion? Many
of them incorporate the frequency (or Time in hertz, I'm assuming) domain
to pick up the dimensional conversion as well.

Thanks...

Matthias
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