5 ms·

I love these kind of inadvertent measurements. One of my favorite examples is that a sufficiently accurate IMU can get you relatively accurate longitude measure

I love these kind of inadvertent measurements. One of my favorite examples is that a sufficiently accurate IMU can get you relatively accurate longitude measurements from the Coriolis effect.

emptiestplace 2y ago
https://en.m.wikipedia.org/wiki/Inertial_measurement_unit https://en.m.wikipedia.org/wiki/Inertial_measurement_unit
adolph 2y ago
Slight correction, latitude, not longitude. The earth’s surface closer to the poles has less distance to travel for any rotation than the surface closer to the equator. As a result the inertial navigation systems of long distance systems must be adjusted. Iirc, this is also the case for artillery firing computations. https://www.oxts.com/blog/going-round-circles-earth-rotation-inertial-navigation/ https://www.oxts.com/blog/going-round-circles-earth-rotation... https://www.britannica.com/science/latitude https://www.britannica.com/science/latitude
- billyjmc 2y ago
  Coriolis corrections are thrown into sniper ballistic calculations, too. Not a huge effect in most conditions, but not zero, and there have been a lot of long shots in the past two decades.
  - psunavy03 2y ago
    "Oi! Suzy!"
01HNNWZ0MV43FF 2y ago
Is that the same thing where a flat-earther tried to measure something with an expensive laser gyro and kept finding that Earth was rotating?
- adolph 2y ago
  I think the most you can tell from an IMU or gyro is that there is a change in velocity in a direction aligning with East-West when there is a change in location and that the change in velocity is greater when the location changes in line with North-South. The change in velocity would be greater as one approaches the poles and lesser at the equator. Thought experiment: if I zeroed my IMU at the North pole and traveled in a straight line away from the pole along longitude zero, following the guidance of the IMU. By the time I got to 45° latitude I’d be traveling Westward at 1,180 kph (.95 Mach) to keep the IMU at zero.
  - trueshape 2y ago
    The flat earther used a fibre optic gyro. You don't "zero" it, it continuously outputs a measurement of its own angular rate around it's sensitive axis. For a 3-axis gyro placed still on earth, it will read about 15 degree/hour around wherever the axis of earth is oriented.
nielsole 2y ago
Asahi Linux (and likely MacOS too) uses the resistance of the speakers coils to detect overheating of same speakers and reduces volume.
- derhuerst 2y ago
  https://github.com/AsahiLinux/speakersafetyd https://github.com/AsahiLinux/speakersafetyd
  - CamperBob2 2y ago
    Interesting. If the voltage across the speaker voice coil can be sampled with enough sensitivity at a fast-enough rate, you have an undocumented microphone.
    - xyzzy_plugh 2y ago
      This is true of all speakers
      - CamperBob2 2y ago
        Exactly.
      - ssl-3 2y ago
        It's true of all dynamic speakers -- the sort with a voice coil and a magnet. (But not all speakers are dynamic speakers.)
        planewave 2y ago
        Would this also be true for electrostatic speakers as well? Though would probably would require greater gain/amplification or, potentially the application of some kind of bias voltage for the capacitive diaphragm of the speaker. Just speculation based on the shared operating principal with condenser microphones
psunavy03 2y ago
I believe this is one of the initial steps an aircraft INS uses to find north while it is aligning, but it's been too long since I had aircraft systems theory in the front of my brain.
- t0mas88 2y ago
  Yes, from earth rotation the INS could figure out true north if the latitude is known. Or figure out the latitude if current heading is known. But normally it's aligned with a starting position from pilot input or GPS.
  - psunavy03 2y ago
    As I recall, it's a combination of things all happening at once, to include using last known location at shutdown, GPS inputs (if available) and inertial inputs. There were various workarounds you had to use in the Navy, where the ship has not only usually moved from the last place the jet thought it was, but it's generally moving as the jet tries to re-align itself. GPS made things easier, and there wasn't a whole lot of thinking involved, but it always took the jet a bit more (or a lot more depending on model) thinking to get a stable platform underway.
  - VBprogrammer 2y ago
    If you are at an airport you will sometimes notice large signs giving Longitude and Latitude of the individual stands at an airport. These are used to give the initial position to the INS via the FMS. Of course these are now all built into the database these days so are only used (if at all) for gross error checking.
deleted 2y ago
[deleted]
cameldrv 2y ago
Latitude or Longitude?
baybal2 2y ago
[dead]
sam_dam_gai 2y ago
Do you mean latitude?

I love these kind of inadvertent measurements. One of my favorite examples is that a sufficiently accurate IMU can get you relatively accurate longitude measurements from the Coriolis effect.

emptiestplace 2y ago

https://en.m.wikipedia.org/wiki/Inertial_measurement_unit https://en.m.wikipedia.org/wiki/Inertial_measurement_unit

adolph 2y ago

Slight correction, latitude, not longitude. The earth’s surface closer to the poles has less distance to travel for any rotation than the surface closer to the equator. As a result the inertial navigation systems of long distance systems must be adjusted. Iirc, this is also the case for artillery firing computations. https://www.oxts.com/blog/going-round-circles-earth-rotation-inertial-navigation/ https://www.oxts.com/blog/going-round-circles-earth-rotation... https://www.britannica.com/science/latitude https://www.britannica.com/science/latitude

billyjmc 2y ago
Coriolis corrections are thrown into sniper ballistic calculations, too. Not a huge effect in most conditions, but not zero, and there have been a lot of long shots in the past two decades.
- psunavy03 2y ago
  "Oi! Suzy!"

01HNNWZ0MV43FF 2y ago

Is that the same thing where a flat-earther tried to measure something with an expensive laser gyro and kept finding that Earth was rotating?

adolph 2y ago
I think the most you can tell from an IMU or gyro is that there is a change in velocity in a direction aligning with East-West when there is a change in location and that the change in velocity is greater when the location changes in line with North-South. The change in velocity would be greater as one approaches the poles and lesser at the equator. Thought experiment: if I zeroed my IMU at the North pole and traveled in a straight line away from the pole along longitude zero, following the guidance of the IMU. By the time I got to 45° latitude I’d be traveling Westward at 1,180 kph (.95 Mach) to keep the IMU at zero.
- trueshape 2y ago
  The flat earther used a fibre optic gyro. You don't "zero" it, it continuously outputs a measurement of its own angular rate around it's sensitive axis. For a 3-axis gyro placed still on earth, it will read about 15 degree/hour around wherever the axis of earth is oriented.

nielsole 2y ago

Asahi Linux (and likely MacOS too) uses the resistance of the speakers coils to detect overheating of same speakers and reduces volume.

derhuerst 2y ago
https://github.com/AsahiLinux/speakersafetyd https://github.com/AsahiLinux/speakersafetyd
- CamperBob2 2y ago
  Interesting. If the voltage across the speaker voice coil can be sampled with enough sensitivity at a fast-enough rate, you have an undocumented microphone.
  - xyzzy_plugh 2y ago
    This is true of all speakers
    - CamperBob2 2y ago
      Exactly.
    - ssl-3 2y ago
      It's true of all dynamic speakers -- the sort with a voice coil and a magnet. (But not all speakers are dynamic speakers.)
      - planewave 2y ago
        Would this also be true for electrostatic speakers as well? Though would probably would require greater gain/amplification or, potentially the application of some kind of bias voltage for the capacitive diaphragm of the speaker. Just speculation based on the shared operating principal with condenser microphones

psunavy03 2y ago

I believe this is one of the initial steps an aircraft INS uses to find north while it is aligning, but it's been too long since I had aircraft systems theory in the front of my brain.

t0mas88 2y ago
Yes, from earth rotation the INS could figure out true north if the latitude is known. Or figure out the latitude if current heading is known. But normally it's aligned with a starting position from pilot input or GPS.
- psunavy03 2y ago
  As I recall, it's a combination of things all happening at once, to include using last known location at shutdown, GPS inputs (if available) and inertial inputs. There were various workarounds you had to use in the Navy, where the ship has not only usually moved from the last place the jet thought it was, but it's generally moving as the jet tries to re-align itself. GPS made things easier, and there wasn't a whole lot of thinking involved, but it always took the jet a bit more (or a lot more depending on model) thinking to get a stable platform underway.
- VBprogrammer 2y ago
  If you are at an airport you will sometimes notice large signs giving Longitude and Latitude of the individual stands at an airport. These are used to give the initial position to the INS via the FMS. Of course these are now all built into the database these days so are only used (if at all) for gross error checking.

deleted 2y ago

[deleted]

cameldrv 2y ago

Latitude or Longitude?

baybal2 2y ago

[dead]

sam_dam_gai 2y ago

Do you mean latitude?