4 ms·

Reminds 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 heavi

by drb999 3y ago

Reminds 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 out intermittently. Then work fine and the rest of the day and on Sunday… a crane, building a new residential building would operate during those hours right in the middle of the microwave path. Many weeks of theories and time wasted until someone had a chance to visit. :)

Sharlin 3y ago
Amazing. Reminds me of the fact that militaries really don't want wind turbines in areas where good radar coverage is important (case in point: the Finnish Defense Forces anywhere near the Russian border); even though the blades aren't metal, they're still a source of noise and radar shadow.
- swores 3y ago
  I'm not at all knowledgable about this, but: is it feasible (and if so, hard?) or impossible to have some sort of live reporting from the turbines about the speed/position of their blades that connects to the radar system allowing it to ignore what it knows to be turbine noise/shadow and therefore be able to have turbines there and still get good radar?
  - smcl 3y ago
    Even if you ignored the turbines themselves, there would still be a "shadow" behind the turbines though I think? Which means you'd have a blind spot every now and then (when the wind is blowing and the turbines are active) which could be exploited by an enemy
    - obi1kenobi 3y ago
      Even if you are looking at the turbines "edge-on," there's probably going to be a noticeable Doppler return as well. Plastic drones with plastic propellers are still visible on radar because the tiny propellers spin super fast, so they light up like a Christmas tree on Doppler radar because the approaching vs receding velocities of the blades are so different.
      - swores 3y ago
        Any chance you can explain to this idiot (me) the flaw in my thinking? https://news.ycombinator.com/item?id=39903084 https://news.ycombinator.com/item?id=39903084
        obi1kenobi 3y ago
        Seems like another user with way more experience than me did an excellent job explaining the situation -- I enjoyed reading their answer!
  - Sharlin 3y ago
    Well, you can't just ignore a radar shadow or noise. Just like GP's point-to-point microwave link couldn't just "ignore" the crane. You can't make a bad Wi-fi connection faster by just telling your computer to ignore the wall between you and the hot spot. A wind turbine is a solid obstacle that conceals stuff behind it, and even if a single turbine might not be a big deal, most commonly someone interested in harnessing wind power would want to build an entire farm, which would be much worse.
    - swores 3y ago
      My (probably ignorant) thinking was that if there weren't propellers, just stalks, they could be arranged in a pattern that radar setups at multiple locations could see through gaps and between them have no dark spaces caused by the towers. Leaving the problem that the blades essentially block out an entire circle, but if the radar software knows the position of every turbine's blades (by a combination of turbines reporting location/speed/acceleration of blades in real time and maybe modelling so the radar system can know in time at least fairly if not very accurately where all blades are in a field of them) then when a radar bounces of one it can say "that doesn't count as a hit" leaving only non-turbine objects showing up in the UI that the radar setup outputs? Is it that radar can't ping / receive at a high enough frequency to distinguish the difference between "this fraction of a ms the blade was at that location so we don't care about the radar hitting something, but the next fraction of a ms the blade had moved and we still got a ping from just behind it so there's something there"? Or some other problem with the idea?
      - juitpykyk 3y ago
        Depends on the width of the radar beam. They are certainly not thin like a laser. It might not fit in the gap between the blades.
      - ColinWright 3y ago
        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 helps detection, but reduces target discrimination. It helps get the energy past the turbines, but you tend to have "wound down" the power output to allow for that. So it doesn't really help.[1] You know where the turbines are ... knowing the exact positions of the blades won't help at the frequencies being used. In short, it's complicated. Radar pulses are like HUGE lumps of energy flying through space, and delicate things like turbine blades chop them up and defect them around, preventing them from getting to, and then from, the targets. [0] Marine radars, X-Band and S-Band. There are other ranges and bands. [1] Yes, this is all extremely simplified and inaccurate, but I'm trying to give a sense of what's going on.
mschuster91 3y ago
At that point, I'd have called a bush pilot to fly along the lines!
ozim 3y ago
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.
- rawbot 3y ago
  Reading log files with really obscure error messages might as well be reading a magical grimoire. Especially when the solution turned out to have nothing to do with the error message.
  - ozim 3y ago
    Hey but that is not a discussion, that's just throwing anecdote to bring other person down or make yourself feel better.
    - SiempreViernes 3y ago
      The funny thing is this comment could have just as well been made on the grandparent and would read just as well.
- nestes 3y ago
  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...

by drb999 3y ago

Sharlin 3y ago

Amazing. Reminds me of the fact that militaries really don't want wind turbines in areas where good radar coverage is important (case in point: the Finnish Defense Forces anywhere near the Russian border); even though the blades aren't metal, they're still a source of noise and radar shadow.

swores 3y ago
I'm not at all knowledgable about this, but: is it feasible (and if so, hard?) or impossible to have some sort of live reporting from the turbines about the speed/position of their blades that connects to the radar system allowing it to ignore what it knows to be turbine noise/shadow and therefore be able to have turbines there and still get good radar?
- smcl 3y ago
  Even if you ignored the turbines themselves, there would still be a "shadow" behind the turbines though I think? Which means you'd have a blind spot every now and then (when the wind is blowing and the turbines are active) which could be exploited by an enemy
  - obi1kenobi 3y ago
    Even if you are looking at the turbines "edge-on," there's probably going to be a noticeable Doppler return as well. Plastic drones with plastic propellers are still visible on radar because the tiny propellers spin super fast, so they light up like a Christmas tree on Doppler radar because the approaching vs receding velocities of the blades are so different.
    - swores 3y ago
      Any chance you can explain to this idiot (me) the flaw in my thinking? https://news.ycombinator.com/item?id=39903084 https://news.ycombinator.com/item?id=39903084
      - obi1kenobi 3y ago
        Seems like another user with way more experience than me did an excellent job explaining the situation -- I enjoyed reading their answer!
- Sharlin 3y ago
  Well, you can't just ignore a radar shadow or noise. Just like GP's point-to-point microwave link couldn't just "ignore" the crane. You can't make a bad Wi-fi connection faster by just telling your computer to ignore the wall between you and the hot spot. A wind turbine is a solid obstacle that conceals stuff behind it, and even if a single turbine might not be a big deal, most commonly someone interested in harnessing wind power would want to build an entire farm, which would be much worse.
  - swores 3y ago
    My (probably ignorant) thinking was that if there weren't propellers, just stalks, they could be arranged in a pattern that radar setups at multiple locations could see through gaps and between them have no dark spaces caused by the towers. Leaving the problem that the blades essentially block out an entire circle, but if the radar software knows the position of every turbine's blades (by a combination of turbines reporting location/speed/acceleration of blades in real time and maybe modelling so the radar system can know in time at least fairly if not very accurately where all blades are in a field of them) then when a radar bounces of one it can say "that doesn't count as a hit" leaving only non-turbine objects showing up in the UI that the radar setup outputs? Is it that radar can't ping / receive at a high enough frequency to distinguish the difference between "this fraction of a ms the blade was at that location so we don't care about the radar hitting something, but the next fraction of a ms the blade had moved and we still got a ping from just behind it so there's something there"? Or some other problem with the idea?
    - juitpykyk 3y ago
      Depends on the width of the radar beam. They are certainly not thin like a laser. It might not fit in the gap between the blades.
    - ColinWright 3y ago
      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 helps detection, but reduces target discrimination. It helps get the energy past the turbines, but you tend to have "wound down" the power output to allow for that. So it doesn't really help.[1] You know where the turbines are ... knowing the exact positions of the blades won't help at the frequencies being used. In short, it's complicated. Radar pulses are like HUGE lumps of energy flying through space, and delicate things like turbine blades chop them up and defect them around, preventing them from getting to, and then from, the targets. [0] Marine radars, X-Band and S-Band. There are other ranges and bands. [1] Yes, this is all extremely simplified and inaccurate, but I'm trying to give a sense of what's going on.

mschuster91 3y ago

At that point, I'd have called a bush pilot to fly along the lines!

ozim 3y ago

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.

rawbot 3y ago
Reading log files with really obscure error messages might as well be reading a magical grimoire. Especially when the solution turned out to have nothing to do with the error message.
- ozim 3y ago
  Hey but that is not a discussion, that's just throwing anecdote to bring other person down or make yourself feel better.
  - SiempreViernes 3y ago
    The funny thing is this comment could have just as well been made on the grandparent and would read just as well.
nestes 3y ago
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...