[HN Gopher] Phyphox - Physical Experiments Using a Smartphone
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Phyphox - Physical Experiments Using a Smartphone
Author : _Microft
Score : 170 points
Date : 2026-04-12 08:38 UTC (14 hours ago)
(HTM) web link (phyphox.org)
(TXT) w3m dump (phyphox.org)
| _Microft wrote:
| The title was slightly editorialized for clarity.
| henryAlbigale wrote:
| Cool app dude
| q3k wrote:
| Good toolkit to have around. Recently used it to verify the true
| RPM of a system (using the accelerometer spectrum tool) against
| its control loop implementation.
| TeMPOraL wrote:
| Indeed. I always keep it installed on my devices, as it turns
| the phone into a poor man's tricorder, and that's handy
| sometimes.
|
| Most recently I used it to check light levels at home in
| different rooms, to determine where we need to boost or replace
| LED strips. Sure, there's million Lux meter apps, but Phyphox
| is better than all of them _and_ demonstrates why these things
| shouldn 't be dedicated apps in the first place. In the past I
| also made use of EM and vibration frequency displays to
| troubleshoot hardware.
|
| A complement to that is
| https://play.google.com/store/apps/details?id=org.intoorbit....
| which, once upon a time, helped me track down a source of rage-
| inducing, late-night high-frequency beeping that was driving us
| insane - down to specific apartment in a block on the other
| side of the street. I ended up friends with those neighbors,
| after teaching them how to disable the alarm clock on their
| Bluetooth radio when they go away for a weekend.
| crtasm wrote:
| also on https://f-droid.org/en/packages/de.rwth_aachen.phyphox/
| eru wrote:
| Compare
| https://play.google.com/store/apps/details?id=cc.arduino.sci...
| Aachen wrote:
| cc.arduino.sciencejournal for anyone else who is wondering
| what's behind HN's ellipsis
| slow_typist wrote:
| There is a paper you can cite if you use phyphox
| professionally.[1]
|
| In Germany phyphox is quite popular in physics education.
|
| However on android the sampling rate of the acceleration sensor
| is limited to 50/s. At least if you install through the official
| app store.
|
| [1] https://iopscience.iop.org/article/10.1088/1361-6552/aac05e
| user_7832 wrote:
| > However on android the sampling rate of the acceleration
| sensor is limited to 50/s. At least if you install through the
| official app store.
|
| My understanding is that it's the same even on iOS (or at least
| on my iPhone SE 2020). More specifically, the _output_ only
| measures till 50hz (but the sensor sampling rate is actually
| 100hz - Nquist, you need double the measured frequency as
| sampling frequency, yada yada.)
| user_7832 wrote:
| By the way, it's important to note that measuring vibrating
| things can permanently damage the OIS VCs in the camera.
| (See: Apple's warning against motorcycle mounts.) my iPhone
| already had a broken OIS so I didn't mind as much.
| slow_typist wrote:
| I get 100/s on an iPhone SE2. 50/s on a Samsung Galaxy A16
| which was released in 2024 or 2025, but that is due to an API
| restriction. You can export from phyphox (.xslx or .cvs). You
| get timestamps in the first column. Phyphox refers to the raw
| data rate, not Nyquist freq.
|
| The sensors have analog lowpass filters that can be adjusted
| in order to avoid aliasing.
|
| In general, with more bandwidth you can do more intrusive
| things. But if you want to tell wether two people ride in the
| same car, 50 Hz should be sufficient anyways.
|
| Phyphox has a smartphone sensor database:
|
| https://phyphox.org/sensordb/
| Aachen wrote:
| Huh? I get 500 Hz here on a Samsung from 2019 and make use of
| it regularly. Sensor frequency is one of the things I check
| before buying a new phone, surely newer Android versions
| haven't killed that with new api restrictions?!
|
| Edit: no, it can't have. Then the phone sensor database would
| show that since it is built from submissions within Phyphox:
| https://phyphox.org/sensordb/
|
| I'm not sure what problem you're running into (perhaps a very
| unusual phone that has only a 50 Hz accelerometer) but
| Android/Phyphox can do way more than 50 Hz
| slow_typist wrote:
| It is a Samsung a16 and it is just an observation I made, not
| a problem at all. If it was, I would try another installation
| source or even switch to a degoogled OS first to get more
| control over the hardware. Only thing I tried to get more
| samples was fiddling with the App restrictions. But it really
| doesn't matter at all.
| extraduder_ire wrote:
| Does the version on f-droid not have that limitation?
| slow_typist wrote:
| That is a possibility, didn't check
| tomaskafka wrote:
| It's the GOAT - I showed the app to a bunch of secondary school
| physics teachers and they were thrilled.
| samch wrote:
| One of my kids has science project due each quarter in school,
| and this is our go-to app. We've measured acceleration in an
| elevator, sound attenuation of an audio source in a small vacuum
| chamber, and the Doppler effect. The app makes it easy to capture
| and export the data points to make graphs. I highly recommend
| this even just to play around with.
| DaSHacka wrote:
| I've been using Trail Sense [0] for sensor-related information
| after learning about it from a friend.
|
| The interface is more polished, but the information is less
| technical than Phyphox (as the app is geared towards being a
| survival toolkit).
|
| [0] https://github.com/kylecorry31/Trail-Sense
| perlgeek wrote:
| I used it just the other day.
|
| My parents have a sound bowl, and I wanted to know the resonance
| frequency. Took an audio spectrum, zoomed in on the first peak,
| read the frequency (iirc it was around 208 Hz).
| davidhoell wrote:
| The coolest thing I ever did with that was finding wires in a
| friends wall - we needed to drill a hole and it was unclear
| whether the wires went up (problem) or right from the outlet. I
| didn't have a cable finder on hand but did have the epiphany to
| put a large load on the outlet (we used a kettle, a hairdryer
| would also work, just needs a lot of watts) and use the Fourier
| transform magnet spectrum to find the 50 Hz grid frequency in the
| wall. Worked beautifully.
|
| Sadly, since most smartphone magnetometers seem to have a sample
| rate of 100/s, this will not be applicable to Americans and
| everyone else with a 60 Hz grid frequency, the 50 Hz were already
| at the Nyquist-Shannon limit.
| gus_massa wrote:
| > _this will not be applicable to Americans and everyone else
| with a 60 Hz grid frequency, the 50 Hz were already at the
| Nyquist-Shannon limit._
|
| The trick should work fine, but you may confuse the 60Hz signal
| with a 40Hz signal [1] [2].
|
| This should work for higher frequencies too, but if the
| frequency is toooo high the problem is that the magnetometers
| averages a short period of time (or use a window) instead of
| being an actual an instant measurement.
|
| [1] Calculated using my fingers moving in the air. 60=50+10 ->
| 50-10=40. I think it's 40Hz, but I would need a pencil and
| paper to be sure.
|
| [2] https://en.wikipedia.org/wiki/Aliasing
| fragmede wrote:
| (40Hz's right)
|
| The hack you can do is to additionally sample at, say, 97Hz
| as well as 100Hz. A 97Hz sampling rate will then see a 60 Hz
| aliased to 40Hz signal go from 40Hz to 37Hz, showing that
| your signal is probably actually really 60Hz and not 40Hz. If
| it was 40Hz at 100 and 97Hz sampling frequency, then it's
| probably actually 40Hz.
|
| (It's been a looong time since signals class though.)
| slow_typist wrote:
| If your sample rate is 100 Hz you would usually apply analog
| lowpass filtering at around 40 Hz, well below Nyquist. But with
| enough load on the line, since no filter has perfect
| attenuation in the stop band...
| OuterVale wrote:
| I've had great fun using Phyphox to visualise my hand getting
| closer/farther from my phone based on the presence of my magnet
| implant. So many cool little things the app can visualise and
| measure, especially when used it creative ways.
| xnx wrote:
| Seems like a more advanced version of Arduino Science Journal
| https://www.arduino.cc/education/science-journal/
| sudb wrote:
| I think there's loads of scope to use phone cameras as
| dataloggers too, especially for older equipment that doesn't have
| an easy way to connect/export the data.
|
| (I've been meaning for ages to write a piece of software that's
| able to extract change over time data from a video of a 7 segment
| display, like on a balance or a digital thermometer or something)
| black6 wrote:
| If you prefer not to deal with an app store:
| https://www.apkmirror.com/apk/rwth-aachen-university/phyphox...
| gozjsbtm wrote:
| Coincidentally, I downloaded the app yesterday. In 10 min, in my
| mitchen, I found g ~ 9.7 m/^2 using a cheap kitchen spring scale
| and the accelerometer (without g) sensor. Quality app.
| trebligdivad wrote:
| Damn that's very impressive - for a long time Android had a lot
| of hopeless accelrometer, audio scope, etc apps, and it's always
| been hard to add your own stuff to it. Sounds very very neat!
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