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+--- Thread: Doppler with free fall bluetooth speaker? (/showthread.php?tid=1430)
Doppler with free fall bluetooth speaker? - Erik Josefsson - 09-18-2021
Hello,
Did anyone try to drop a BT speaker from 2 meters and measure the doppler effect?
The rotating gear in this video by Lukas and Thomas is great:
https://www.youtube.com/watch?v=r4Nl7oIzCco
but perhaps you can measure doppler with just a BT speaker falling towards a phyphox phone?
Best regards.
//Erik
RE: Doppler with free fall bluetooth speaker? - solid - 09-19-2021
Hello,
I did not, but I measured doppler using a pendulum and two smartphones with independent measurements of the velocity by the gyroscope of the smartphone on the pendulum. Smartphone on the pendulum measured the Doppler frequency shift and a second smartphone was used as generator of 1000 Hz sound. A time shift between two signals had to be compensated...
doppler_pendulum_gyroscopeY(dg1).pdf (Size: 87.14 KB / Downloads: 419)
RE: Doppler with free fall bluetooth speaker? - Erik Josefsson - 09-19-2021
Thanks solid! Very nice, and that setup is simple enough.
Actually, just 3 Hz phone shaking in front of a 440 Hz youtube video shows doppler 440±2 Hz, but also strange flat one second long slopes every second second between otherwise nicely sine shaped curves (in groups of three, i.e. also every second second).
Seen those (see png)?
What makes them?
Best regards.
//Erik
RE: Doppler with free fall bluetooth speaker? - solid - 09-20-2021
Hi Erik,
I do not understand your result. What particular 440 Hz YouTube video you have used? When I am shaking telephone with doppler experiment in front of another one with 440 Hz I have the expected result shown below. Only the noise is much higher than in your experiment.
With Brest regards
Mikhail
RE: Doppler with free fall bluetooth speaker? - Erik Josefsson - 09-20-2021
Sine Wave A- 440 Hz Concert Pitch for Ten Hours - Test Tone
https://www.youtube.com/watch?v=xGXYFJmvIvk
Played it on a standard HP laptop.
And I was shaking an old Galaxy III phone with 120 bpm (used a metronome before measurement to get the right tempo) maybe half a meter from the laptop (direction was towards and from the laptop, with phone microphone facing laptop). It was quite silent in the room.
Best regards.
//Erik
RE: Doppler with free fall bluetooth speaker? - solid - 09-20-2021
Hi Erik,
thanks for the precise decription of your measurements. I tried to reproduce it but I got a result very similar to the above experiment with 2 smartphones...
Best
Mikhail
RE: Doppler with free fall bluetooth speaker? - Erik Josefsson - 09-21-2021
I should also have added settings.
I tried again and got the attached screenshot (same pattern) with:
Base frequency: 440 Hz
Frequency range: 10 Hz
Time step: 50 ms
Speed of sound 340 m/s
When trying Time step 20 ms graphs get jagged.
With 10 ms I get gibberish (but still straight lines).
Old phone? F-droid version of phyphox? Both?
Best regards.
//Erik
RE: Doppler with free fall bluetooth speaker? - Jens Noriʇzsɔɥ - 09-21-2021
Apparently, there is regularly missing data. Could you share the data export of your results (including the meta data on your device)?
RE: Doppler with free fall bluetooth speaker? - Erik Josefsson - 09-22-2021
(09-21-2021, 11:05 AM)Jens Noritzsch Wrote: Apparently, there is regularly missing data. Could you share the data export of your results (including the meta data on your device)?
Hi Jens! Didn't save the data files, but here's my phone data:
phyphox
Version: 1.1.9
Build: 1010901
File format: 1.13
Permissions
INTERNET: yes
RECORD_AUDIO: yes
READ_EXTERNAL_STORAGE: yes
BLUETOOTH: yes
BLUETOOTH_ADMIN: yes
ACCESS_COARSE_LOCATION: yes
ACCESS_FINE_LOCATION: yes
ACCESS_NETWORK_STATE: yes
WAKE_LOCK: yes
CAMERA: yes
Device
Model: GT-I9300
Brand: samsung
Board: m0
Manufacturer: samsung
ABIS: API < 21
Base OS: API < 23
Codename: REL
Release: 4.3
Patch: API < 23
Sensors
Accelerometer (type 1)
- Name: LSM330DLC 3-axis Accelerometer
- Range: 19.6133 m/s²
- Resolution: 0.009576807 m/s²
- Min delay: 10000 µs
- Max delay: API < 21 µs
- Power: 0.23 mA
- Vendor: STMicroelectronics
- Version: 1
Magnetic Field (type 2)
- Name: AK8975C 3-axis Magnetic field sensor
- Range: 2000.0 µT
- Resolution: 0.06 µT
- Min delay: 10000 µs
- Max delay: API < 21 µs
- Power: 6.8 mA
- Vendor: Asahi Kasei Microdevices
- Version: 1
Magnetic Field (type 14)
- Name: AK8975C Magnetic field Sensor UnCalibrated
- Range: 2000.0 µT
- Resolution: 0.06 µT
- Min delay: 10000 µs
- Max delay: API < 21 µs
- Power: 6.0 mA
- Vendor: Asahi Kasei Microdevices
- Version: 1
unknown (type 3)
- Name: iNemoEngine Orientation sensor
- Range: 360.0
- Resolution: 0.015625
- Min delay: 10000 µs
- Max delay: API < 21 µs
- Power: 7.8 mA
- Vendor: STMicroelectronics
- Version: 1
Light (type 5)
- Name: CM36651 Light sensor
- Range: 121240.0 lx
- Resolution: 1.0 lx
- Min delay: 0 µs
- Max delay: API < 21 µs
- Power: 0.2 mA
- Vendor: Capella
- Version: 1
Proximity (type 8)
- Name: CM36651 Proximity sensor
- Range: 8.0 cm
- Resolution: 8.0 cm
- Min delay: 0 µs
- Max delay: API < 21 µs
- Power: 1.3 mA
- Vendor: Capella
- Version: 1
Gyroscope (type 4)
- Name: LSM330DLC Gyroscope sensor
- Range: 8.726646 rad/s
- Resolution: 3.0543262E-4 rad/s
- Min delay: 5000 µs
- Max delay: API < 21 µs
- Power: 6.1 mA
- Vendor: STMicroelectronics
- Version: 1
unknown (type 9)
- Name: iNemoEngine Gravity sensor
- Range: 9.80665
- Resolution: 0.009576807
- Min delay: 10000 µs
- Max delay: API < 21 µs
- Power: 6.1 mA
- Vendor: STMicroelectronics
- Version: 1
Linear Acceleration (type 10)
- Name: iNemoEngine Linear Acceleration sensor
- Range: 8.726646 m/s²
- Resolution: 0.009576807 m/s²
- Min delay: 10000 µs
- Max delay: API < 21 µs
- Power: 6.1 mA
- Vendor: STMicroelectronics
- Version: 1
Attitude (type 11)
- Name: iNemoEngine Rotation_Vector sensor
- Range: 8.726646
- Resolution: 3.0543262E-4
- Min delay: 10000 µs
- Max delay: API < 21 µs
- Power: 6.1 mA
- Vendor: STMicroelectronics
- Version: 1
Pressure (type 6)
- Name: LPS331AP Pressure Sensor
- Range: 1260.0 hPa
- Resolution: 2.4414063E-4 hPa
- Min delay: 40000 µs
- Max delay: API < 21 µs
- Power: 0.045 mA
- Vendor: STMicroelectronics
- Version: 1
unknown (type 22)
- Name: Auto Rotation Sensor
- Range: 255.0
- Resolution: 0.0
- Min delay: 0 µs
- Max delay: API < 21 µs
- Power: 0.0 mA
- Vendor: Samsung Electronics
- Version: 1
Attitude (type 11)
- Name: Rotation Vector Sensor
- Range: 1.0
- Resolution: 5.9604645E-8
- Min delay: 10000 µs
- Max delay: API < 21 µs
- Power: 13.13 mA
- Vendor: Google Inc.
- Version: 3
unknown (type 9)
- Name: Gravity Sensor
- Range: 19.6133
- Resolution: 0.009576807
- Min delay: 10000 µs
- Max delay: API < 21 µs
- Power: 13.13 mA
- Vendor: Google Inc.
- Version: 3
Linear Acceleration (type 10)
- Name: Linear Acceleration Sensor
- Range: 19.6133 m/s²
- Resolution: 0.009576807 m/s²
- Min delay: 10000 µs
- Max delay: API < 21 µs
- Power: 13.13 mA
- Vendor: Google Inc.
- Version: 3
unknown (type 15)
- Name: Game Rotation Vector Sensor
- Range: 1.0
- Resolution: 5.9604645E-8
- Min delay: 10000 µs
- Max delay: API < 21 µs
- Power: 6.33 mA
- Vendor: Samsung Electronics
- Version: 3
Gyroscope (type 4)
- Name: Uncalibrated Gyroscope Sensor
- Range: 8.726646 rad/s
- Resolution: 3.0543262E-4 rad/s
- Min delay: 5000 µs
- Max delay: API < 21 µs
- Power: 13.13 mA
- Vendor: Samsung Electronics
- Version: 1
unknown (type 3)
- Name: Orientation Sensor
- Range: 360.0
- Resolution: 0.00390625
- Min delay: 10000 µs
- Max delay: API < 21 µs
- Power: 13.13 mA
- Vendor: Samsung Electronics
- Version: 1
Gyroscope (type 4)
- Name: Corrected Gyroscope Sensor
- Range: 8.726646 rad/s
- Resolution: 3.0543262E-4 rad/s
- Min delay: 5000 µs
- Max delay: API < 21 µs
- Power: 13.13 mA
- Vendor: Google Inc.
- Version: 1
Best regards.
//Erik
RE: Doppler with free fall bluetooth speaker? - Erik Josefsson - 09-23-2021
(09-22-2021, 05:34 AM)Erik Josefsson Wrote:Hello again,(09-21-2021, 11:05 AM)Jens Noritzsch Wrote: Apparently, there is regularly missing data. Could you share the data export of your results (including the meta data on your device)?
Please find attached both screenshots and csv-data from the same "experiment" (with the same phone) as before.
Best regards.
//Erik