Re: Opinions on SI

Darren Long <darren.long@...>

Comments in-line.

On 24/11/12 17:37, k7udr wrote:

After a recent presentation I was approached by a fellow Ham who noted that my presentation did not conform to SI (International system of units). He offered a training exercise in the proper usage which I accepted. I must admit, I was ignorant of SI prior to that time.

Apparently, SI is taught in grade school throughout the world, whereas my US education seems to be lacking.

So I went through my material fixing obvious offenders, like proper capitalization and the use of a space between value and units.

the K in kilo should be lowercase


70cm should be 70 cm
12VDC should be DC 12 V (looks pretty awkward to me)

The former versions look better to me.  Better 70cm than 2.3ft.

I then learned that bps should be b/s and dBm don't exist. Further ppm is incorrect.

Either bps or b/s is fine with me, as is ppm.

Now I've never seen b/s used by anyone, anywhere and I certainly wouldn't want a table of values expressed as:

dB referenced to 1 mW

instead of dBm

dBm FTW!

When I purchase an oscillator, tolerance is expressed in ppm, so apparently the manufacturers are unaware of their non-conforming usage.

Am I out of touch with reality? Are you offended by 56 kbps?

I'd like to hear others thoughts on this, particularly those of you educated somewhere other than the US

Those are my thoughts.  I learned the SI system at school and have an engineering degree.  I may laugh at the imperial units system on a regular basis but there's nothing wrong with the examples you've quoted. 

I'd rather not get drawn into a discussion on gibibits and those other awful prefixes though.  Confusion often arises from the notion that 1kB can not be sent in 8 seconds through a 1kb/s channel, as 1kB is 1*2^10 bytes and 1kb/s is 1*10^3 bits per seconds, but more confusion arises from using ridiculous prefixes.  For that reason alone, I prefer sticking to the base unit of bps or b/s.

I think you've been trolled :P


Darren, G0HWW

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