Akin's Laws of Spacecraft Design (2011) [pdf]

Post by avmich » Thu, Jan 01, 2026, 5:33 PM UTC

nancyminusone wrote: post #37

Geonode wrote: post #29

Earlier quoted context omitted.

He promises 10, gives the world 4, but everybody else has 1, and he's hated for it.

I can't think of any breakthrough successes Musk has had within the last 5 years, unless you count helping the current president get elected. If the promising but still incomplete Starship was on the same pace as the exceptionally successful Falcon 9, it would have already delivered cargo to orbit by now. His rates appear to be slipping.

Post by mlyle » Fri, Jan 02, 2026, 3:31 AM UTC

pjdesno wrote: post #40

> "Trellis coded modulation got this rate up to 50 kilobaud by the 1990s" Not quite, and an interesting story that fits these engineering maxims better than you might think. An analog channel with the bandwidth and SNR characteristics of a landline phone line has (IIRC) a Shannon capacity of 30-something kbit/s, which was closely approached with V.34, which used trellis coded modulation plus basically every other cod…

Post by capyba » Fri, Jan 02, 2026, 3:38 PM UTC

metalman wrote: post #94

potato3732842 wrote: post #56

Earlier quoted context omitted.

Trying to get milk out of the kind of cattle one raises for beef is a pretty good analogy for using an IPO to offload a questionable company onto the public.

realy like the cattle analogy, and it can be extended further, Dexter cattle are dual use cattle, and the worlds smallest breed, so increadably popular for small acerages and single family cows, so in a way the type of thing that is terrifying for big operations, as they are not monetisable at scale, but idealy suited to a distributed network that is also a peer to peer economical exchange.

Post by kinkyusa » Thu, Jan 08, 2026, 4:43 PM UTC

senshan wrote: post #60

db48x wrote: post #58

Earlier quoted context omitted.

No, it’s more like HomeModem ←A→ Exchange1 ←D→ Exchange2 ←A→ ISPModem. The digital parts were all inside the telco’s networks that connect the exchanges to each other. > Couldn't you send data at megabits per seconds over a mile long copper wire without using modems at all (using just UARTs?). No. The exchange is sampling the analog signal coming in over your phone line at 8kHz and 8 bits per sample. They just design…

The S/CNN for both trunk and nonloaded subscriber loop circuits shall not be less than 31 dB. 4kHz/2*log2(1+10^(31dB/10)) ~ 60.3kBps [0] https://www.ecfr.gov/current/title-7/subtitle-B/chapter-XVII...

Post by kinkyusa » Thu, Jan 08, 2026, 4:44 PM UTC

mlyle wrote: post #103

pjdesno wrote: post #40

> "Trellis coded modulation got this rate up to 50 kilobaud by the 1990s" Not quite, and an interesting story that fits these engineering maxims better than you might think. An analog channel with the bandwidth and SNR characteristics of a landline phone line has (IIRC) a Shannon capacity of 30-something kbit/s, which was closely approached with V.34, which used trellis coded modulation plus basically every other cod…

> An analog channel with the bandwidth and SNR characteristics of a landline phone line has (IIRC) a Shannon capacity of 30-something kbit/s, The problem is that the ADC in the telephone exchange is not clocked coherently to your modem. You're paying various companding, quantization (time and level), etc, losses-- it is not a nice linear channel. An end-to-end analog connection could be capable of significantly more-…