Discovering The Air Cannon

120dB;
critical listening to harm;
5 gallons of propane provides
18000 blasts

Using agricultural air cannons south of Corvallis has been excessive this month. Farmers with discipline crops are sometimes beset with Canadian Geese overwintering within the Willamette Valley. To scare the geese away, they steadily use propane air cannons on timers. Beginning on January fifth, an air cannon started firing each two minutes all day and all through the night time. My sleep and that of many neighbors was disrupted for practically a month.

Attempting to determine the place the cannon photographs originated, I drove out and listened from a number of places. It was loud on Airport Highway, Bellfountain Rd, 53rd St, Plymouth Dr, Nash Ave, Brooklane Dr, Wake Robin Highway, Rivergreen Ave and as far north because the Benton County Honest Grounds. It was silent anyplace south of Llewellyn Rd. Attempting to get a heading for the sound with simply my ears and a compass was far more tough than I anticipated.

The Corvallis Airport
wanting South

All indications have been that the sound was coming from the realm of the airport, however I couldn’t pin it down any extra precisely. The airport employees denied utilizing an air cannon. Nonetheless, they indicated that they may hear one to the south.

Probably the most simply identifiable farm south of the airport was Venell Farms. They fervently denied they have been utilizing an air cannon.

That left a giant chunk of land south and west of the airport that was not crossed by public roads. Not prepared to trespass to search out the supply, I wanted a brand new technique.

After some deep thought, I theorized I may pinpoint the placement of the air cannon by logging the arrival instances of the sound from three places. It took three folks stationed at distant places miles aside utilizing a synchronized clock on our cell telephones. We every waited over the identical ten minute interval, noting the precise time for every of the 5 cannon photographs that we heard.

The sound arrived at our Bellfountain Rd location first. About 4 seconds later, the sound arrived at our Brooklane Dr. lookout. Two seconds later, it arrived at our Rivergreen Ave listening publish.

I took a display screen seize of a Google Map of our space with a measurement line on the map for scale. I plotted our three listening places. The size allowed us to determine how far aside our check places have been and facilitated a way for translating backwards and forwards between the picture coordinate system and the actual world coordinate system.

I wrote a program in Python (see source code below) that might iterate all of the factors within the picture within the search space the place we suspected the air cannon sat. Translating these picture factors to actual world coordinates, I used the velocity of sound at 35℉ to calculate the journey time to every of our three listening posts. Evaluating the arrival instances of the simulated sounds, I may match them with the deltas from the actual observations. As soon as my program scanned and examined each level on the south half of the map picture, it recognized a degree that precisely replicated the deltas. I knew I discovered the one potential origin of the sound and subsequently the placement of the air cannon. I translated my grid system again to actual world coordinates and plotted it on my map. That recognized the offending farm discipline.

Offended goose doesn’t like
air cannons

See Also

The Naturalist and the Great, Lovable, So Good, Very Daring Jay

I went to the County Tax Assessor Workplace to search out the proprietor of the property. With an organization identify, I discovered a Site and a cellphone quantity.

I known as the proprietor of the farm (headquartered in Monmouth) and requested in the event that they used an air cannon on their property close to the Corvallis airport. They confirmed that they do. I requested in the event that they run it at night time, they mentioned they don’t. Nonetheless, the supervisor mentioned that he’d contact the folks working onsite. Twenty minutes later, he known as again reaffirming they aren’t operating their cannons at night time. He additionally assured me that their air cannons couldn’t be heard greater than a mile away. The air cannon that we tracked to his farm was clearly audible 6 miles away from the Benton County Fairgrounds. I didn’t belief his data of his personal tools nor the way it was utilized by the onsite employees.

Nonetheless, in a tremendous coincidence, the air cannons stopped that very night of our cellphone dialog (Thursday, January 25). The air cannons have fallen silent at night time since that day. I believe that the cessation was not a random correlation. I surmise that they really have been utilizing the cannon at night time and the supervisor stopped the follow.

It was a depressing twenty days of ruined sleep. I discovered threads in regards to the air cannon on Fb, Reddit, Twitter/X and Nextdoor. How many individuals in Corvallis and Philomath have been disrupted?

I’m refraining from revealing the identify of the farm. I don’t need people harassing them. I’ll say, although, it wasn’t Venell Farms as so many anticipated.

Ought to the nighttime air cannon begin up once more, I’ve a straightforward instrument to determine its precise location from miles away. I’ll train this newly discovered energy at any time when I would like it.

#!/usr/bin/env python3

from math import sqrt, isclose
from functools import partial

from factors import Level, Block
from configmanners import Namespace, configuration
from configmanners.converters import str_to_list

terrible_number = 100000

def distance(p1, p2):
    return sqrt((p2.x - p1.x) ** 2 + (p2.y - p1.y) ** 2)


str_to_Point = partial(
    str_to_list, item_converter=float, list_to_collection_converter=Level
)

str_to_Block = partial(
    str_to_list, item_converter=int, list_to_collection_converter=Block
)


def all_points_within_block_iter(a_block):
    for x in vary(a_block.left, a_block.proper):
        for y in vary(a_block.higher, a_block.decrease):
            yield Level(x, y)


required_config = Namespace()
required_config.add_option(
    "A_in_px",
    default=Level(58.34, 844.29),
    doc="level A in pixel coordinates",
    from_string_converter=str_to_Point,
)

required_config.add_option(
    "B_in_px",
    default=Level(846.05, 290.27),
    doc="level B in pixel coordinates",
    from_string_converter=str_to_Point,
)
required_config.add_option(
    "C_in_px",
    default=Level(1574.73, 453.96),
    doc="level C in pixel coordinates",
    from_string_converter=str_to_Point,
)
required_config.add_option(
    "AB_time_delta",
    default=4.0,
    doc="time delta between listening posts A and B",
    from_string_converter=str_to_Point,
)
required_config.add_option(
    "AC_time_delta",
    default=6.0,
    doc="time delta between listening posts A and C",
    from_string_converter=str_to_Point,
)
required_config.add_option(
    "BC_time_delta",
    default=2.0,
    doc="time delta between listening posts B and C",
    from_string_converter=str_to_Point,
)
required_config.add_option(
    "AB_in_m",
    default=3800.0,
    doc="distance in meters between factors A and B",
)
required_config.add_option(
    "speed_of_sound_in_mps",
    default=332.24,
    doc="the velocity of sound in meters per second",
)
required_config.add_option(
    "search_box_in_px",
    default="400, 1000, 1200, 2000",
    doc="coodinate extents in pixels of the search space",
    from_string_converter=str_to_Block,
)


config = configuration(required_config)

scale = config.AB_in_m / distance(config.A_in_px, config.B_in_px)


def test_fitness(test_point_in_px):
    SA_in_m = distance(config.A_in_px, test_point_in_px) * scale
    SB_in_m = distance(config.B_in_px, test_point_in_px) * scale
    SC_in_m = distance(config.C_in_px, test_point_in_px) * scale

    TA_in_s = SA_in_m / config.speed_of_sound_in_mps
    TB_in_s = SB_in_m / config.speed_of_sound_in_mps
    TC_in_s = SC_in_m / config.speed_of_sound_in_mps

    test_AB_delta = abs(TB_in_s - TA_in_s)
    if not isclose(test_AB_delta, config.AB_time_delta, abs_tol=0.1):
        return terrible_number

    test_AC_delta = abs(TA_in_s - TC_in_s)
    if not isclose(test_AC_delta, config.AC_time_delta, abs_tol=0.1):
        return terrible_number

    test_BC_delta = abs(TB_in_s - TC_in_s)
    if not isclose(test_BC_delta, config.BC_time_delta, abs_tol=0.1):
        return terrible_number

    # return the deviation from the sum of the deltas as a fittness worth
    return abs(
        test_AB_delta
        + test_AC_delta
        + test_BC_delta
        - config.AB_time_delta
        - config.AC_time_delta
        - config.BC_time_delta
    )


best_fitness = terrible_number
best_point = None
for test_point_in_px in all_points_within_block_iter(config.search_box_in_px):
    health = test_fitness(test_point_in_px)
    if health < best_fitness:
        best_fitness = health
        best_point = test_point_in_px


if best_point is not None:
    print(f'{best_point=} at {best_fitness=}')
else:
    print('the air cannon just isn't within the search space')