Open imjasonh opened 2 years ago
vijayp
commented
2 years ago you can probably get a directional microphone so that you can ensure the sound only comes from above? and/or use doppler shift to ensure that it's a helicopter moving in the same direction (and speed/height) as the aircraft data.
imjasonh
commented
2 years ago Yeah I was thinking of also trying to limit to frequencies that correlate with helicopters based on experience. I don't think I need to train an ML model but who knows.
In the meantime I was thinking, since I want a preview-tweet option that gets pushed to me anyway to confirm it's a helicopter. At that point, as a super lazy (boring) option, I might as well just use my own expertly trained human ears to detect the helicopter anyway, and just open a webpage when I hear one, see the preview tweet, and hit send.
I apparently live under a very common flight path for helicopters flying from Manhattan to the Hamptons, a fact that's especially apparent on Fridays and Sundays in the summer when there seem to be a lot of them going out or back. It wouldn't be a real problem except they fly really low, and pretty fast, and they're really loud. I have no idea whether they're at the legal altitude or whatever, but I do know they're loud and annoying.
Whenever I hear a particularly low/loud one, I open https://globe.adsbexchange.com/ on my phone to find it, and they're sometimes as low as 700 ft, going 120 knots (138 mph for land folk). Here's one going 140 mph, 375 feet above my head. This page says that's 75-87 dB from the ground, not harmful except for long periods, but, quote, "you may feel annoyed by the noise." Can confirm.
There's a page to report helicopter to the FAA, but honestly who expects that to lead to anything.
(from There’s No One in Charge of New York’s Noisy Helicopters)
Let's see if we can collect some data then, even if it's just over our small high-traffic slice of Brooklyn. ADSB has an API that's available for $10/month, with an endpoint to list aircraft within 1 nautical mile (1.15 land miles, wtf just use land miles ya boatnerds). If I can set up an RPi on the roof with a microphone that sends some signal when it detects noise over some dB level and triggers a request to list nearby helicopters, I can see if I can find one that's flying low and fast and grab its tail number. It'd be a good opportunity to learn some stuff.
With all the hard part out of the way, it'd be relatively easy to have a Twitter bot tweet the tail number, altitude, speed, noise level from the ground, and a little picture showing it on a map, maybe a recording of the noise. If I can get it to tweet while the thing's still overhead, followers can have push notifications tell them what's overhead while it's still there.
One complication is that I also live near a not-quiet expressway, so I'd need to make sure I don't get false alarms from horns honking, sirens, etc. But as a guess if it's 70+ dB for more than 2 seconds and there's a low-flying helicopter nearby, it's the helicopter's noise.