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From: Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>
Newsgroups: sci.electronics.design
Subject: Re: Instead scopes
Date: Sat, 31 Aug 2024 20:14:35 -0000 (UTC)
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john larkin <jl@650pot.com> wrote:
> On Sat, 31 Aug 2024 17:59:04 -0000 (UTC), Phil Hobbs
> <pcdhSpamMeSenseless@electrooptical.net> wrote:
> 
>> john larkin <jlarkin_highland_tech> wrote:
>>> On Thu, 29 Aug 2024 21:50:19 +0100, liz@poppyrecords.invalid.invalid
>>> (Liz Tuddenham) wrote:
>>> 
>>>> john larkin <jl@650pot.com> wrote:
>>>> 
>>>>> On Thu, 29 Aug 2024 16:15:59 GMT, Jan Panteltje <alien@comet.invalid>
>>>>> wrote:
>>>>> [...]
>>>>>> Calculators yes.
>>>> 
>>>>> We weren't alowed to use a calculator on exams because it would give
>>>>> an unfair advantage to the students that could afford one.
>>>> 
>>>> We were allowed mechanical calculators (Facits etc.) but there were only
>>>> enough for half the candidates.  Half of us were locked in a room with a
>>>> spare envigilator acting as a guard while the other half sat the exam
>>>> then we swapped places and the ones who had taken the exam were locked
>>>> in while the second group sat the exam.
>>>> 
>>>> Electronic calculators did not exist, but we did learn to program an
>>>> analogue computer where 100v = 1 Machine Unit.
>>> 
>>> A lot of current engineering practise is left over from the days when
>>> computing was expensive or non-existant. Things like s-parameters and
>>> Smith charts.
>> 
>> I’ve done a lot of lowish-power RF stuff, and mostly agree with you about
>> the practicality of using S parameters in hand calculations. 
>> 
>> However, I cordially disagree with your sentiments regarding Smith charts. 
>> 
>> For one thing, they’re super useful for designing optical coatings, but
>> that’s a minority interest on SED. 
>> 
>> In RF work one runs into a lot of matching jobs involving modulated sine
>> waves. 
>> 
>> One typical example from my work is coupling sine modulation into a diode
>> laser, for modulation-generated carrier interferometry.  (*)
>> 
>> A Smith chart makes it super easy to try out different schemes, such as
>> series/shunt stubs, lumped elements, or any combination thereof. 
>> 
>> Useless for bandwidths of an octave or more, and so apt to be undervalued
>> by crass time-domain types. ;)
> 
> The interesting parts of the world are wideband and nonlinear. So are
> we.

I noticed. ;)

> 
> Sine waves are BORING.

You’ve been hanging out with the wrong crowd, obviously.  Tsk tsk. 

Cheers 

Phil Hobbs 
> 
> 



-- 
Dr Philip C D Hobbs  Principal Consultant  ElectroOptical Innovations LLC /
Hobbs ElectroOptics  Optics, Electro-optics, Photonics, Analog Electronics