23
votes
Accepted
How accurate is my phone's magnetometer?
So then I thought, "Perhaps the phone's magnetometer is just not designed for this range of magnetic field strength; It's really supposed to be just the a compass, and the earth's magnetic field ...
- 8,227
9
votes
Acceleration when device is on tilt
Your main mistake is in not treating acceleration as a single vector. When the car is at rest, that vector will always be 1 g upwards. Don't look at just the X component of the raw accelerometer ...
- 315k
8
votes
Accepted
Magnetometer thermal drift
According AN4602, the chip can compensate thermal drift with internal temperature sensor
Not exactly. According to AN4602, the sensor "internally compensating sensitivity drift over temperature ...
- 13.1k
7
votes
How accurate is my phone's magnetometer?
How accurate is my phone's magnetometer?
In its intended range of operation? As a rule of thumb they are quite accurate, better than 8 bits of accuracy after a 2-point calibration, and more than 10 ...
6
votes
Accepted
Magnetic Field around step-down converters
The magnetic field near circuitry carrying about 1 amp could be a problem 20cm away, but for a compass application you can get there if a few steps are taken in the design. I would wind toroids for ...
- 11.8k
5
votes
Acceleration when device is on tilt
As other answers have stated, the accelerometer provides a three dimensional vector which is the sum of gravity and other acceleration on the car due to the engine, brakes, or other forces acting on ...
- 57.9k
5
votes
Accepted
Mystery SOT-143 Part on Magnetometer
The voltage divider divides the 5 volts in half and makes what you have labeled as "2.5 V" as an analog reference so that your signal can swing positive and negative. You might redraw your ...
- 11.8k
3
votes
Acceleration when device is on tilt
As a very basic approach, you can use a high-pass filter to eliminate the constant part of the acceleration (which corresponds to gravity) and keep the variable part of which is due to car dynamics. ...
- 26k
3
votes
Acceleration when device is on tilt
You would need a fusion algorithm and use 3D-accelerometer, 3D-Gyro and 3D-Magnetic sensors. With this fusion algorithm you get the attitude, the earth gravity helps as reference to detect the horizon ...
- 24.5k
3
votes
Accepted
Realistic Magnetometer Specifications
If the magnetic sensor will saturate they provide reset straps on magnetometers for degaussing. If those aren't working then your exceeding the maximum filed strength of the HMC5883L magnetometer, ...
- 88.8k
3
votes
Accepted
Can a "static" magnetic field carry Information?
A static field (indeed, any static symbol) conveys no information, by
Shannon's theorem. This is because the probability of the state is
1, there is only one 'symbol', and if it is unchanging, the ...
- 7,801
3
votes
Accepted
Magnetometer (LIS3MDL) temperature reading changes with orientation
I recaptured data and plotted the temperature individually against each magnetometer axis. From the plots below, its apparent that the temperature data was actually the x-axis data.
I believe this ...
- 639
3
votes
Accepted
Which is give better result for find angular position of device using 9-axis IMU snesor.?
Thanks a lot to all for your greater Support.
I have found some interesting Reference website. which give the best method to implement both to find meaningful data like, pitch & Roll.
Guide to ...
- 157
3
votes
Which is give better result for find angular position of device using 9-axis IMU snesor.?
You need some kind of algorithm to fuse the acceleration, rotational rate and magnetic field readings. There are several different ways to do this, from simple complementary HP/LP-filters to more ...
- 31
3
votes
Which is give better result for find angular position of device using 9-axis IMU snesor.?
Generally you determine angle by using the accelerometer readings. This only works is the unit is not accelerating at the time but you can do a quick sanity check that sqrt(x*x + y *y + z *z) = 1g +/- ...
- 6,992
3
votes
I2C pull-up resistors and voltage
The folks at Adafruit have thought of this for you. If you go to the Adafruit site you linked to for the HMC5883L, they tell you this about the SDA and SCL lines for I2C:
So my interpretation of this ...
- 2,912
3
votes
Accepted
I2C pull-up resistors and voltage
Thus, the I2C lines are referenced to a voltage of 5 volts
Nope. They are referenced to a GND.
connecting 3.3 volts from the Nano to the corresponding pin on the
sensor
Don't do this! The 3.3V on ...
- 13.1k
3
votes
Maintaining constant magnetic field strength with temperature
This boils down to a 1e-7 precision measurement of magnetic field without gain drift. The 1e-7 is "easy"; gain drift is hard.
Hall sensors easily resolve 7 orders of magnitude, but are ...
- 23.4k
3
votes
Maintaining constant magnetic field strength with temperature
Probably looking at a fluxgate sensor. COTS devices can have +/-100pT/°C tempco and reasonable noise over a 1Hz bandwidth (which should suffice for thermal compensation).
But this sounds a bit like a ...
3
votes
Accepted
Do factory calibrated electronic compasses need to be re-calibrated in the field?
Yes, calibration inside a large ferromagnetic object, such as a car, does mean that the compensation is only correct at that spot inside that car. For a portable compass, compensation should be done ...
- 5,271
2
votes
Accepted
How is the degaussing feature in the HMC5883L 3-Axis Digital Compass chip correctly used?
I know this is an old thread, but I encountered it while trying to resolve a problem with my quadcopter compass. I think the confusion about "degaussing" the HMC5883L comes from what appears to be ...
- 106
2
votes
How is the degaussing feature in the HMC5883L 3-Axis Digital Compass chip correctly used?
Why it's called degaussing...
Degaussing is traditionally thought of as a demagnetizing procedure. It's apt here, but you have to think of that magnetization in terms of its super-posed components.
...
- 12.7k
2
votes
Bosch BNO055 gyroscope bias stability
Not enough rep to comment, but wanted to correct a comment by @John Birckhead. The bias instability is the minimum on the Allan Variance curve, which represents low-frequency noise (similar to drift) ...
- 21
2
votes
Recording heading with magnetometer that is inside spinning object
Nope. You can't tell the direction of travel of a ball, with only the 3-axis magnetometer. The magnetometer doesn't "see" the translational component.
Let's take a ball that can have a ...
- 38.6k
2
votes
Radiation Effects on Electronics
Semiconductors can be damaged/destroyed when exposed to radiation.
I worked at a particle accelerator facility (TRIUMF, Vancouver BC) and once installed a regulated power supply mounted in a steel ...
- 60.8k
2
votes
Radiation Effects on Electronics
Energy levels are inverse to wavelength so shielding depends on both. Start with energy specs and IO lines & electronics that need protection.
Are you planning any nuclear tests?
Each ...
- 148k
2
votes
Accepted
When to use a Hall probe and when a fluxgate magnetometer to measure magnetic fields?
I don't know the threshold for where you could use either, but a Hall Sensor is used for much higher current and detects magnetic force from the Hall Effect while some magnetometers can detect a ...
- 148k
2
votes
Arduino frequency measurement to 2 or 3 decimal places
The problem is that the code is counting how many pulses happen during the measurement period. If you measure for 1 second, you have 1 Hz resolution. For 0.1 Hz or 0.01 Hz resolutions you need to ...
- 172k
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