Re: 465 Scan Expansion Mesh


dhuster@...
 

Stan,

Yeah, try to get most people to agree that the addition of the engine
computer on a car was a step forward. I think the step forward was
the fact that I have yet to not have a computerized car start within
2-3 seconds whether the temperature was -10°F or +110°F. The step
backward is how, with so many vehicles being produced that (1)
manufacturers over the world haven't settled on a common computer
platform and (2) that to replace one costs as much as my full-blown
home computer. I think the latter is simply because the
manufacturers have us poor consumers by the kahoonies and know it.

And back to the mesh vs. other methods. Not only can one compare
meshless CRTs from the 1960's to the 465/475 and now to the digital
scopes, but look at the digital scope displays. They're going to be
limited not only because of the ±1 digit bobble, but because of the
finite resolution of an LCD or a tri-color CRT dot pitch. No point
in using ADCs with resolution better than the display resolution
unless you have a method of "magnifying" the vertical and/or
horizontal to take advantage of the increase ADC resolution. I've
not looked up the LCD and color CRT specs to see where the two
resolutions converge. Might be interesting! It's an issue not
unlike having a 4-1/2 digit DMM display and only 0.5% accuracy on DCV
and 1% accuracy on ACV.

By the way, I had forgotten about the phosphor change. The P31 is
more durable, that's for sure. I have seen a few P11's that were
wrecked on 7904's and 485's that were being used for nuclear research
out in Amarillo. They were always set up with a camera (obviously,
with a P11) waiting for a single-shot event with the intensities
cranked up to max. They were a BIG market for the 7104 in the OKC
field office.

And regarding nuclear research, I remember a field engineer telling
me about selling a lot of transient digitizers to the nuclear
research community. They'd put a TD down a hole with a bomb with the
cabling leading to the blockhouse a couple of miles away. They'd
blow up the bomb and the TD would send the signal out of all the
stuff they were monitoring -- about 1µs before it went into total
meltdown -- and then in the blockhouse monitoring station, they'd
wait for the signal to show up and then after it was captured, high-
speed clamps shut the lines down so the the massive EMP that was
right on the tail of the data didn't totally destroy all the
monitoring equipment. But the poor transient digitizers .... they
got to make one and only one measurement in their entire lives before
that serial number ceased to exist. Danged expensive probe!

Dean

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