Arnold Tibus wrote:
On Sun, 11 Oct 2009 12:10:36 +0000, Mark Sims wrote:
Alas, if there was only an FM to R... there is some useful information in the
revision history/comments near the beginning of the file heather.cpp
The OSC graph defaults to OFF because it tends to be a very jagged and noisy
looking graph that gets rather annoyingly in the way of things. The next rev
of the program has a display filtering option that makes that plot look a lot
more tame.
The OSC param is shown in PPB in the status info at the top of the screen since
that is the way it comes into the program. It is shown in PPT in the plots
since that gives values that are much easier read against the scale divisions
on the screen. I have considered converting to PPT in the status info,
can't remember why it stayed PPB...
----------------------------------------
RTFM comes to mind:-)
Mark,
personally I have some promlems with the expressions as in LH
ppb, ppt etc. used because there are different meanings about
around the world and this is therefore misleading, error-prone.
If I search in the Internet I do find lots of discussions about.
Is there no way for an improvement, no standardization?
There is an international standard for it. It is part of the SI standard
which is also realized in ISO 31.
http://en.wikipedia.org/wiki/International_System_of_Units
However, the first map could indicate why you have troubles.
I learned that in Germany (and all over continental Europe?)
1 thousend = 1.000 = E3
1 million = 1.000.000 = E6
1 milliard = 1.000.000.000 = E9
1 billion = 1.000.000.000.000 = E12
1 billiard = 1.000.000.000.000.000 = E15
1 trillion = 1.000.000.000.000.000.000 = E18
1 trilliard = 1.000.000.000.000.000.000.000 = E21
and so on with
quartrillion, quartrilliard, quintillion, quintilliard, sextillion,
sextilliard....
and in the US and some more countries it is
million = 1,000,000
billion = 1,000,000,000
trillion = 1,000,000,000,000
and further ...? ( fantastillions acc. Donald Duck ;-)) )
wouldn't it be more scientific and less error-prone to agree at least to
xE-3 instead of (m)
xE-6 instead of ppm (µ)
xE-9 instead of ppb (n)
xE-12 instead of ppt (p)
xE-15 instead of pp? etc. (f)
xE-18 (a)
(how do one express parts per mili...(E-3)?)
or if not wanted perhaps then this way :
x10^-6
x10^-9
x10^-12
etc.
or could one type eg. m, µ, p, f, a for milli, mikro, nano; pico, femto, atto?
These later two are standard representations. A particular problem is
that not all text formats contains the my symbol, so u has been an
accepted shorthand and so far this have not been result of confusion.
The 1.0E-6 form is adapted to ASCII computerized form, any should maybe
be avoided if possible.
When used these numbers in calculations we anyway have to convert
these ppm, ppb, ppt etc. to scientific numbers using exponents
4,6 µ can be confusing compared to 4,6 ppm as part-per- indicate a
normalized relative measure. This is as handy as in percent, promille,
part-per-milion etc. I can't recall a suitable means to handle it, but
you can write it in the ugly for of 4,6 µHz/Hz which would only convey
the normalization part and not the relative aspect (f-f0)/f0.
There are too often discussions and misunderstandings
because the ignored case sensitivity of units (b for bit, B for Byte,
m for milli, M for Mega...).
This can only be solved by means of education and correction.
Notice that 1 MB is to be interprented in 1.000.000 Bytes in SI
standard. If you want 1.048.576 Bytes you shall now write it as 1 MiB.
http://en.wikipedia.org/wiki/Mebi
It's ugly, i know, but solves the problem and is consistent.
Btw. I remember to all these strange mmH, µµF etc. when I collected
rare inductors, capacitors revovered from vintage MIL- equipment in
the end fifties/ early sixties of last century ... :-)
You still see stuff like 0,001 uF and 0,010 uF regularly, even if they
should be baned as their propper form of 1 nF and 10 nF is what should
be used.
I find myself using the shorthand of inserting the prefix number in
place of the decimal point, as this can easilly become hart to read, so
a 2k2 resistor is easy to convey in schematics and ASCII formats, while
2,2 kOhm is more propper.
The carefull reader will discover my use of the "," for decimal place
and "." for digit separation. The US convention works the other way
around. It is also part of the US adaptation of the SI standard, so care
should be taken not to interprent the NIST publication as conveying the
correct detail for certain things, they are only to be viewed as local
interpretation to the USA, possibly only recommended use.
I believe that Time Nuts prefer precise and clear expressions!? ;-)
What do you think about it?
There is still some debate to be had. I don't recall that there is a
propper "SI style" relative normalized form. Need to check the docks,
but if someone could enligthen me that would be super.
Cheersm
Magnus
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