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Why do some radio towers blink?

jeffgeerling.com

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Re: Why do some radio towers blink?

#101

Post by wiml »

mulmen wrote: post #37
scblock wrote: post #25

Earlier quoted context omitted.

It's so pilots see the entire wind farm as a single entity and can interpret what they see and understand the extent of the wind farm easily. There is a pretty good study you can read on this: https://www.airporttech.tc.faa.gov/DesktopModules/EasyDNNNew... As to community impact, radar-activated lighting is an approach that is being used in places this is a concern. It allows the lights to remain off unless there is…

Does it have to be radar? Can it use ADS-B?

At small unattended airfields, you can sometimes turn on the field lights by transmitting on a particular frequency (as if you were calling the non-existent tower in quick succession).

https://www.aopa.org/news-and-media/all-news/2017/march/flig...

(Of course, in this case it works because the pilot already knows the airfield is there.)

Re: Why do some radio towers blink?

#102

Post by sleepy_keita »

ssl-3 wrote: post #98
genter wrote: post #82

Earlier quoted context omitted.

I was told that you want lights on all 3 phases so that you can see spinning things spin. If the lights are on single phase, they will dim 120 times a second, and the strobe effect can cause spinning things to appear stationary. With 3 phase, at least 1/3 of the lights are lit all the time.

How did that work, do you suppose? How does one connect a lamp to 3-phase power? Are/were there 3-phase fluorescent tubes available? Or are we relying on the spinny-thing that is to be observed to somehow be illuminated by all three phases, with three lamps or fixtures, simultaneously? Without such malarcky as shadows or inverse-square to muddy our vision? Or maybe a multiplicity of single fixtures with 3 tubes -- on…

They're saying that you have 3 banks of lights, each connected to one phase of the 3 phase input. That way, when only 1 bank goes out, it's easy to see that one phase is out.

Re: Why do some radio towers blink?

#103

Post by ThePowerOfFuet »

anyfoo wrote: post #79
georgefrowny wrote: post #75

Earlier quoted context omitted.

You could still sync with that signal because it's not perfect. For example, say you have a scheme where a period longer than the last one is symbol A, about the same period is B and shorter is C. You will get a random-ish sequence of symbols. If you have an algorithm that, say, resets the timer to zero whenever a certain symbol sequence is detected, you can eventually get back in sync. With some care you can make su…

Maybe you'll get a kick out of this, I did it in a bored afternoon a while back: echo -ne '\e[8;32;90;t';n=20;t=524292;l=$((t-1));m=$((2**n-1));c=0;xs=(1);ys=(1);for ((i=0;i >1)^(b*t)));c=$(((c >30));ys=($y $ys[1]);yd=$((120+(y >> 24)));printf '\e[48;5;%um ' $yd};done It is entirely self-contained (but needs zsh, not bash, for dumb reasons). Terminal at 90 columns works best. It is just a very simple integer LFSR as…

What... the... fuck. Mind blown.

The zsh dependency is super unfortunate, though :(

Re: Why do some radio towers blink?

#104

Post by alex_young »

I love the narrative storytelling here, but the takeaways seem somewhat obvious.

Lights on towers mean stuff, especially to airplanes.

Lights are required for tall towers, and get this, towers next to airports.

You can guess how tall a tower is by looking at the lights.

Re: Why do some radio towers blink?

#105

Post by teslatree »

punnerud wrote: post #48

Never seen a blinking light on a tower in Norway. Why the difference between countries, can’t be that huge difference risk if some don’t have them?

In Norway this is regulated by Luftfartstilsynets BSL E 2-1, and the blinking white lights on our towers are called "hinderlys", for example category "Høyintensitet, type B".

They are not uncommon in Norway.

If you go to one of our major airports you will see one on the tower. The blinking lights also sit on wind turbines and TV masts, and anything taller than 15 meters in rural areas or 30 meters in populated areas will have some kind of light on it, sometimes blinking, either red or white.

Re: Why do some radio towers blink?

#108

Post by georgefrowny »

ThePowerOfFuet wrote: post #103
anyfoo wrote: post #79

Earlier quoted context omitted.

Maybe you'll get a kick out of this, I did it in a bored afternoon a while back: echo -ne '\e[8;32;90;t';n=20;t=524292;l=$((t-1));m=$((2**n-1));c=0;xs=(1);ys=(1);for ((i=0;i >1)^(b*t)));c=$(((c >30));ys=($y $ys[1]);yd=$((120+(y >> 24)));printf '\e[48;5;%um ' $yd};done It is entirely self-contained (but needs zsh, not bash, for dumb reasons). Terminal at 90 columns works best. It is just a very simple integer LFSR as…

What... the... fuck. Mind blown. The zsh dependency is super unfortunate, though :(

It is amazing! With some brutal hacks to some array indices, and probably some excessive quoting changes it can work in Bash too:

  echo -ne '\e[8;32;90;t'; n=20; t=524292; l=$((t-1)); m=$((2\*n-1)); c=0; xs=(1); ys=(1); for ((i=0; i>1)^(b*t))); c=$((((c>30)); ys=("$y" "${ys[@]:0:1}"); yd=$((120+(y>>24))); printf '\e[48;5;%um ' "$yd"; fi; done
This could probably be submitted to https://github.com/attogram/bash-screensavers/blob/main/gall...

Re: Why do some radio towers blink?

#110

Post by themafia »

alex_young wrote: post #104

I love the narrative storytelling here, but the takeaways seem somewhat obvious. Lights on towers mean stuff, especially to airplanes. Lights are required for tall towers, and get this, towers next to airports. You can guess how tall a tower is by looking at the lights.

"My license to operate the tower is contingent upon my ability to appropriately light it."
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