kens

71 ms·

1171.
by kens 4y ago
I should have known that :-) I was curious, so I looked into this a bit more. Monsanto advertised Astroturf in 1971 with the slogan "The new grass-roots movement. It's away from grass, to Astroturf." In the 1980s, grass-roots
1172.
by kens 4y ago
The expression "astroturfed to within an inch of its life" means that most of the reviews are fake recommendations for marketing reasons. Specifically, it's a mixed metaphor, which makes it harder to understand. "Astrotu
1173.
by kens 4y ago
The title here ("100% of Long Covid patients have GPCR-autoantibodies") is editorialized, making this sound interesting. The actual title is "Possible Impact of functional active GPCR-autoantibodies on retinal microcirculatio
1174.
by kens 4y ago
In general I'm not a fan of year-stamping every post but I think it's relevant that this is from 2018.
1175.
by kens 4y ago
I like the "portrait" layout of the currency, compared to "landscape" for regular currency.¹ It makes it clear that there's something unusual about this money, a feature that I'd always taken for granted but su
1176.
by kens 4y ago
The tan box in the article explains this set. The multiples are n×618 where the smallest prime factor of n (not of n×618) is ≥103 (if any). I.e. 618, 103×618, 107×618, 109×618, etc.
1177.
by kens 4y ago
Jay Forrester may be better known here as an inventor of magnetic core memory and creator of the groundbreaking MIT Whirlwind computer (1951).
1178.
by kens 4y ago
I keep a mental list of things that are claimed to have won WW2. Some of them are radar, cryptography, oil, the atomic bomb, industrial production, economic power, Colossus, the Eastern front, hydroelectric power, air power, and rubber. (I&
1179.
by kens 4y ago
I don't suppose anyone has one of these chips? I'd be interested in taking die photos.
1180.
by kens 4y ago
They had printed circuit boards back then but point-to-point wiring was very popular.
1181.
by kens 4y ago
If you prefer blog format to Twitter: https://www.righto.com/2022/05/talking-with-moon-inside-apol... Previous HN comments: https://news.ycombinator.com/item?id=31368713
1182.
by kens 4y ago
A collector loaned us the premodulation processor. I think he got it from RR Auction, which regularly has auctions with lots of amazing space hardware.
1183.
by kens 4y ago
I like the traveling wave tube amplifier because it's such a wild way to amplify a signal. The digital ranging using a pseudorandom sequence is also pretty cool.
1184.
by kens 4y ago
The Lunar Communications Relay Unit (LCRU) on the rover provided S-band communication to Earth (MSFN) for voice, telemetry and TV.
1185.
by kens 4y ago
Yes, the components were spot-welded. This was common in the Apollo electronics. I think it was more reliable than soldering.
1186.
by kens 4y ago
He's done a bunch of videos on the S-band transponder that is connected to the premodulation processor, but hasn't covered the premodulation processor yet.
1187.
by kens 4y ago
Yes, I expect you could put the whole premodulation processor on a single IC nowadays. Even in the late 1960s, an op amp IC could have replaced the amplifiers built from discrete components.
1188.
by kens 4y ago
Author here if anyone has questions about obscure Apollo hardware...
1189.
by kens 4y ago
>So the tank rounds are something like $500 each. I was surprised that the military could get anything for $500, so I looked up tank round prices. They are more like $5000-$10000 (M829A4).
1190.
by kens 4y ago
The motivation for hiding the history of deleted Wikipedia articles is to minimize legal complaints. E.g. if something is libelous or a copyright violation, they want to remove it. https://en.wikipedia.org/wiki/Wikipedi
1191.
by kens 4y ago
> Something is ‘notable’ according not to subjective perception but rather whether you can find third party sources to corroborate basic details. Don't confuse notability and verifiability. Notability requires verifiable evidence, b
1192.
by kens 4y ago
This brings to mind Eric Raymond's bizarre suggestion that he is the most famous programmer in the world: http://esr.ibiblio.org/?p=6839
1193.
by kens 5y ago
The General Belgrano was sunk by a nuclear-powered submarine during the Falklands War (1982). Tomahawk cruise missiles were launched from submarines against Iraq in the Gulf War (1991) and against Yugoslavia in the Kosovo War (1999).
1194.
by kens 5y ago
This page is the companion to my article on the ranging codes yesterday: https://news.ycombinator.com/item?id=31136285 In any case, I'm here to answer questions.
1195.
by kens 5y ago
It depends which signal they retransmit. If they amplified and retransmitted the raw 2 GHz signal, you are correct that it would be the same as a reflection, but stronger. Unfortunately, if the spacecraft is transmitting and receiving on th
1196.
by kens 5y ago
For complete details on how the Apollo ground stations stayed synchronized, see "Apollo Precision Frequency Source and Time Standard" [1]. Stations stayed synchronized to one part in 10^10. Each had two rubidium frequency standard
1197.
by kens 5y ago
The AGC computed the position (including range) using inertial guidance and star sightings by the astronauts. So yes, it was a completely independent system, but the results should be the same.
1198.
by kens 5y ago
Yes, the ground stations were kept in time sync with rubidium atomic clocks and other complex systems. For ranging specifically, the codes were transmitted and received at the same site so time synchronization was not an issue.
1199.
by kens 5y ago
Testing the systems for Apollo was a huge task, more than I can describe here. Everything from component testing to putting a Lunar Module in a giant vacuum chamber on Earth. Each flight pushed things further so they could test in Earth orb
1200.
by kens 5y ago
Author here if anyone has questions. I encourage you to try out the interactive page that shows how the ranging system worked: https://righto.com/apollo/ranging.html

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