Re: OT: Covid's True Origins

On Tue, 22 Apr 2025 15:15:01 -0700, john larkin <jl@glen--canyon.com>
wrote:

On Tue, 22 Apr 2025 22:02:32 +0100, Cursitor Doom <cd@notformail.com>
wrote:
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On Mon, 21 Apr 2025 15:02:17 -0700, john larkin <jl@glen--canyon.com>
wrote:
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On Mon, 21 Apr 2025 22:23:03 +0100, Cursitor Doom <cd@notformail.com>
wrote:
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On Mon, 21 Apr 2025 08:26:40 -0700, john larkin <jl@glen--canyon.com>
wrote:
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[...]

Sine waves are boring.

>
Well, square waves give rise to lots of harmonics which can be useful.
But what about triangles and sawtooths. Any interesting properies
hidden away in those?

>
Periodic waveforms are all boring. They just do the same thing, over
and over.
>
A complex pulse can do interesting things. Spin an airplane. Fuse
deuterium-tritium. Trigger a megaton boom.
>
I wish the world would move on from the slide rule and graph paper
days, narrowband s-parameters and Smith charts and load pulls. We have
computers now.

>
It's dumb *not* to use computers for the complicated and trap-ridden
calculations relating to impedance transformations, filters and
transmission lines. *However* if someone using computers for this
purpose hasn't been schooled in the derivation of the calculations by
learning how the Smith Chart was developed and how it got that scary,
warped shape, then they're going to be too far abstracted from the
underlying physics to be able to understand fully what's going on
under the hood. And they'll be that much poorer for it. Like people
who use rules-based calculus to solve problems because they have
little understanding of the nuts and bolts of derivatives and
integrals. Ask them to solve a new problem and they're lost!

>
No, don't just automate the antique concepts. We need Spice For RF,
genuine wideband time-domain analysis. Anything interesting is
nonlinear anyhow.
>
https://www.ineltek.com/en/qorvo-qspice-neues-simulationstool-fuer-rf-und-leistungselektronik-schaltungsdesigns/

I develop my own Spice models for MMICs and phemts and distributed
amplifiers and other RF parts. That usually involves measurements,
because most RF parts don't even specify DC things. Some data sheets
say "adjust the bias until it works" or "ac couple the input and
output."

I drive electro-optical modulators with narrow pulses. The RF part
data sheets assume a continous, symmetrical sine wave. I can get twice
the swing for pulses if I bias a distributed amp way off-center.

RF parts seem to specify their abs max voltage assuming that a sine
wave might swing from ground to 2xVcc, but the data sheet specifies
abs max Vcc. So one has to cheat.

Testing a $300 distributed amplifier chip for its genuine abs max
output voltage limit is emotionally tricky.