--- Bill Hooper <[EMAIL PROTECTED]> wrote:
....
As discussed earlier, the actual unit in which the value is sent to the
computer is an engineering
decision and could not necessarily be in mA itself. Bear in mind that this is
one machine talking
to another. The size of the increments used is not arbitrary. It is carefully
chosen to maximize
the useful range and precision of measurement given the bandwidth constraints
of the system. In
fact, it isn't even guaranteed to be decimal; many of these systems end up
transmitting things in
something like "4ths of a degree" or "17ths of a volt". This fact is not
fixable and not
necessarily a mistake.
IEEE Std 1616 on motor vehicle event data recorders (the "black boxes
under the drivers' seats") is an excellent example of this. The range of
each variable's expected values is given, the number of bins into which
that range is divided is defined, and the resulting size of each bin is
then inferred. The device itself transmits "number of bin values" (e.g.,
0 to 128) when read out and the readout instrument "translates" this to
normal units. Provision is made in this standard for both metric and
non-metric readouts.
....
All my co-workers can be assumed to know the full set of metric prefixes
(they'll look it up if
they don't), and if they need to discuss a concept that has no name (i.e.
something that naturally
happens in units of 72 millimeters for some reason) they will actually make up
a temporary term to
simplify communication ("OK, this word salad is getting hard to follow. Let's
start calling these
lengths 'lambdas'"). I'm all for simplifying the units used to communicate
formally and to
interact with the ordinary public. But for informal engineering discussions
and the like, those
terms probably still have value.
Neither "centiamps" nor "milliamps" would be acceptable in an IEEE
standard. Unit names are to be spelled out completely or symbolized, as
in "milliamperes" or "mA". It would be acceptable, though not
preferable, to use "centiamperes" or "cA". Nor does IEEE accept "kilos",
"klicks", or the like. In my experience while working in each field,
yes, engineers are more casual (some might say "sloppy") in casual
speech when using these units names but I found that physicists are even
more so.
Jim
--
James R. Frysinger
632 Stony Point Mountain Road
Doyle, TN 38559-3030
(H) 931.657.3107
(C) 931.212.0267
