HackerTrans
TopNewTrendsCommentsPastAskShowJobs

gabesk

no profile record

comments

gabesk
·2 anni fa·discuss
In the simplest analogy, it's just the TV rabbit ears with two wires in opposite directions, except much longer wires, because the frequencies are lower and therefore the wavelength is larger. Those classic rabbit ears are effectively a dipole antenna, which is basically: "stretch a wire out in a line so it's half the wavelength of the frequency you want to receive or transmit on, cut it in half, and send the signal from the middle, out both ends of the cut wire".

https://www.aa5tb.com/dipole.html

Picking that length of wire results in the lowest impedance (kind of analogous to friction) at the radio for pushing signal out to the antenna, but various lengths work with more or less efficiency, and you don't have to send the signal from the middle either if you have appropriate inductors and capacitors to adjust the impedance (it's just the simplest way).

As with most things on the internet these days, it seems the best content is in the form of YouTube videos, so amusingly, this is the best written information I came across after some quick searching:

https://apps.dtic.mil/sti/tr/pdf/AD0684938.pdf
gabesk
·2 anni fa·discuss
Kernel drivers, too. Especially the DMA buffers for devices that don’t support scatter gather: if you don’t allocate them at driver startup, you might not be able to find enough free contiguous regions later. Although maybe that’s not as big of a deal these days, since both Windows and Linux can relocate physical pages.
gabesk
·3 anni fa·discuss
For small amounts of text, another simple way is to paste it into the Run dialog (Winkey-R) and then copy it back out again. Works well for turning URLs into plain text and removing the editor formatting from function names before pasting into a bug report, for example.
gabesk
·3 anni fa·discuss
Just FYI that the link to the page about the case against ultrasonic humidifiers is broken; it's missing the / after the domain. I tried leaving a comment on the page, but even after creating a dummy profile it wouldn't accept it, so hopefully you'll see it here.
gabesk
·3 anni fa·discuss
Not just the first day, but the very first run. They cheaped out and didn't build a bypass for a 30 MPH curve on an otherwise 80 MPH run. Which, while embarrassing enough, shouldn't have resulted in an accident even if the conductor missed the signage as they did, but wasn't because the railways successfully lobbied to delay rolling out Positive Train Control for a few more years. The entire event was just a perfect illustration of the disastrous state of passenger train transit in this country.

[1] https://en.wikipedia.org/wiki/2017_Washington_train_derailme...
gabesk
·3 anni fa·discuss
As I understand it (and I'm not an expert just curious reader), it's part of what ATSC 3 is fixing by moving to OFDM instead of 8-VSB. Multipath in OFDM leads to some (hopefully few) number of subcarriers fading out, which error correction can manage. Conversely, 8-VSB is a regular single carrier (ish) (with 8 different analog signal levels, hence the name), so in order to decide the value of any bits at all the TV needs to identify and delay (line up) many of the ghosts up with the main signal. That's a more challenging signal processing task, especially given the diversity in age of the TV tuners (the ones from the late 2000's didn't have as advanced DSPs).