I was expecting a story about frolicking about in the sun. I'll settle for a hardware troubleshooting adventure.
The Wi-Fi only works when it's raining
291–300 of 331 posts
Re: The Wi-Fi only works when it's raining
#292Earlier quoted context omitted.
Radars work in the 3cm or 10cm ranges[0], so you'll always get a return from the towers and the blades, and that significantly reduces the energy that gets beyond the turbine to illuminate potential targets. Reflections from targets also need to pass the turbine(s), reducing the return even more. Beamwidths are significant, depending on the antenna configuration. You can have beamwidths of 0.5 degrees and more. That…
Thanks! I wouldn't have guessed the sizes were so large for radar, and just assumed that in current era radar would have progressed to the point of even being able to not send pings at the rotating blades in sync with their rotations (ie always firing radar somewhere within the circle but only at the spots where the blades are not) the same way machine guns fired past propellers on WW2 (or WW1?) fighter planes figure…
The details I give are for marine radar, where off-shore wind-farms are a significant issue. But radar in general works on similar wavelengths, and a lot of clever processing can be done to "improve" the images you get back, especially when you have a lot of images that can be combined, rather than sweeping the radar around and only get 20 to 120 sweeps per minute.
There are trade-offs between how often you can ping versus how far you want to see versus how much energy you can send out versus how big the "lumps" are, etc. The sums/calculations are pretty simple, but not obvious until you've seen them, and then they are.
But if you want to see something at 32NM ~ 60km, you have to send out a lot of energy, so the "lumps" need to be pretty big, especially as the returns drop off as a fourth power with distance.
Re: The Wi-Fi only works when it's raining
#293Earlier quoted context omitted.
I'm not following, better than what?
Why would the replacement name you suggested be better than the actual name?
Oh, I see. It wasn't a suggestion for a replacement, hence 'org' in there since they were talking about 'organizers'. They could have called themselves the April Tools. Just a dumb joke/unmissable opportunity to call some perfectly nice-seeming internet strangers a bunch of tools.
Re: The Wi-Fi only works when it's raining
#294Earlier quoted context omitted.
Thanks! I wouldn't have guessed the sizes were so large for radar, and just assumed that in current era radar would have progressed to the point of even being able to not send pings at the rotating blades in sync with their rotations (ie always firing radar somewhere within the circle but only at the spots where the blades are not) the same way machine guns fired past propellers on WW2 (or WW1?) fighter planes figure…
The details I give are for marine radar, where off-shore wind-farms are a significant issue. But radar in general works on similar wavelengths, and a lot of clever processing can be done to "improve" the images you get back, especially when you have a lot of images that can be combined, rather than sweeping the radar around and only get 20 to 120 sweeps per minute. There are trade-offs between how often you can ping…
Any idea to what extent the problems can or can't be solved by money vs. a limit on maximum quality of radar before needing to break the laws of physics to improve further?
E.g. are the US military saying "yep those are the issues we face too" or "haha our tech has more than enough energy to get around all these problems"?
Re: The Wi-Fi only works when it's raining
#295Earlier quoted context omitted.
The details I give are for marine radar, where off-shore wind-farms are a significant issue. But radar in general works on similar wavelengths, and a lot of clever processing can be done to "improve" the images you get back, especially when you have a lot of images that can be combined, rather than sweeping the radar around and only get 20 to 120 sweeps per minute. There are trade-offs between how often you can ping…
Any idea to what extent the problems can or can't be solved by money vs. a limit on maximum quality of radar before needing to break the laws of physics to improve further? E.g. are the US military saying "yep those are the issues we face too" or "haha our tech has more than enough energy to get around all these problems"?
Most of what I know in these areas is either something I can't talk about, or is surmise based on conversations between others when I was around. There's a lot to do with the laws of physics, but equally, many times people have found clever things to do with the data they have.
I wouldn't care to speculate further, but you might want to read about phased array antennas, and FMCW radar. There are some very deep rabbit holes here, and I certainly would not be your best guide.
Re: The Wi-Fi only works when it's raining
#296Earlier quoted context omitted.
Any idea to what extent the problems can or can't be solved by money vs. a limit on maximum quality of radar before needing to break the laws of physics to improve further? E.g. are the US military saying "yep those are the issues we face too" or "haha our tech has more than enough energy to get around all these problems"?
Most of what I know in these areas is either something I can't talk about, or is surmise based on conversations between others when I was around. There's a lot to do with the laws of physics, but equally, many times people have found clever things to do with the data they have. I wouldn't care to speculate further, but you might want to read about phased array antennas, and FMCW radar. There are some very deep rabbit…
Thanks again :)
Re: The Wi-Fi only works when it's raining
#297I remember when I had ADSL2, I would get increased packet loss when it rained. After I failed to find the culprit, technicians from ISPs tried to debug it to no avail. It turned away when the connection got upgraded from ADSL2 to VDSL2.
Re: The Wi-Fi only works when it's raining
#298Reminds me of an extremely similar case with a long distance microwave link at a mobile telecom provider in Australia that I worked for. They relied quite heavily on microwave link chains and this particular one was in northern Queensland where fixed lines were hard to find and no local engineers were locally present/aware of the changing environment. Every week day + Saturday, from 7-3 the link would keep cutting ou…
Love that story. For me it reminds me most debugging I see at work. People coming up with theories and doing some magic incantations on the interface. Instead of reading the log files or reading error description which makes usually error and fix obvious in 10 seconds.
I've done a ton of low-budget analog hardware debugging, and the major problem with hardware debugging is each attempt to fix the problem takes a long time. If I had wanted to test every idea I had I could easily waste a week. Not to mention that I can't just run some automated test suite after the fact. For hardware, approaching debugging methodically is a necessity, not just best practice.
We don't typically have log files for hardware, but I'm always surprised when otherwise extremely intelligent people first try to debug by applying "fixes" that shouldn't have any causal effect on any weird observations we've gotten. I have no problem with people coming up with theories because each modification takes time, but each theory should ideally explain the data...
Re: The Wi-Fi only works when it's raining
#299Earlier quoted context omitted.
I used to be in an adjacent field and we used to joke about when the HFT guys were gonna get working on some neutrino detectors & sources to signal straight through the Earth. You could use them for science on the weekends!
Sounds awesome, to be able to send a signal directly through the whole earth from point to point. It also sounds like origin story of X-Men or a new cancer
Reminds me of Hubble and the NRO satellites and how Hubble was an extra that they didn’t need.
Re: The Wi-Fi only works when it's raining
#300Let me see if I'm the first one to link to that classic story in the same series, "I cannot send email further than 500 miles" http://www.ibiblio.org/harris/500milemail.html Or the Magic/More Magic switch http://www.catb.org/jargon/html/magic-story.html It's fun when physical reality meets the abstract models that we have built in our heads of these machines.
There was a site with stories like these somewhere, I sadly can't remember the URL any more. I think the one that stuck out to me was the Soviet mainframe computer that would get weird bit flips almost every day, always at the exact same time. Somebody compared what was different about the days it didn't get bit flips on, it turns out those were the days on which a particular train didn't run, the computer was very c…
I think is the one you are looking for:
https://beza1e1.tuxen.de/lore/index.html
Also posted on HN awhile back:
https://news.ycombinator.com/item?id=23005140
Edit: yep, here are your Crash Cows: https://beza1e1.tuxen.de/lore/crash_cows.html