Smart Meter Pro (v2.1) manual

Hello. I'm Android boy, the chief developer of Smart Tools co,.

Smart Meter Pro is the NEW 4th set of the Smart Tools suite. It includes 3 tools (sound meter, vibration meter, lux meter), the advanced version of "Sound Meter Pro".

※ Introduction video
 


Ⅰ. Sound Meter
This meter uses your microphone to measure noise levels in decibels (db), and shows you references.

① Main menu
② Statistic (save / load / CSV export)
③ Screen capture
④ Mode (landscape <-> portrait)

⑤ Refresh (with mute) : long-click the center of meter

⑥ Refresh
⑦ Reference <-> Chart
⑧ Brightness : make your screen dim for saving battery
⑨ Play <-> Pause

※ Don't blame this app for Maximum Limitation

Most Android microphones are aligned to human voice (300-3400Hz, 40-60dB). They are enough for voice calls. But there is an issue of 16 bits microphone limitation.

Check the sound pressure in the calibration menu. It'll stop at 32767 (32767=2^15-1). In conclusion, a 16 bits microphone cannot measure above 96 dB. (more link)

Due to manufacturer optimization (background noise reduction), some devices can measure up to 82dB. Galaxy S6-S8 (82-84dB), Galaxy Note20 (87dB). Most of Motorola and Amazon devices are not optimized, so they can measure up to 96 dB.

Last year, a German user suggested a trick to bypass the hardware limitation. Just add 30dB in the calibration menu, and cover the microphone hole with your finger, so that you can measure over 100dB of noise. Try it. :)

※ Menu & Settings

① Upside down : Most smartphones have a microphone hole at the bottom. It is recommended to point the microphone towards the sound source. How? Upside down!

※ How to calibrate Sound Meter ???

Since 2010, we had calibrated the app on 800+ android devices (major Galaxy, LG, Xperia, Motorola and Nexus).

In order to calibrate the app correctly, you must compare it with an ACTUAL sound level meter. Otherwise, ensure that the measured value of a very quiet room is 30-35dB. If the value were out of range, you could add/reduce number at the calibrate menu.

It is an auxiliary tool for reference. Just enjoy it.

※ Level Notification
Many users, especially school teachers, wanted to know if their voices were too loud. In this case, turn on the [Level Notification] option at the settings. 60dB+ : green, 70dB+ : pink,  80dB+ : red.

The sound alarm is not available due to the amplification.

Ⅱ. Vibration Meter
This tool uses a 3-axis acceleration sensor to measure device's vibration, movement and the earthquake, and shows references. There are no units. It converts the values to Modified Mercalli Intensity scale(MMI) for your convenience.

① Alarm on/off
② Refresh
③ Reference <-> Chart

④ Refresh : long-click the center of meter (including mute)

⑤ Brightness : make your screen dim for saving battery
⑥ Y-axis range
⑦ Play <-> Pause

※ Statistic Menu

① Save : enter title name for current chart
② Load : load the charts stored. To remove a chart, long-click and select [delete] option.

③ Export : export current data as a CSV file. Move it to your PC and open it with MS-Excel. This function can store up to 48 hours. Here is an example.

  time[hh:mm:ss],MMI
 12:40:21,2.1
 12:40:22,2.5
 12:40:23,2.3
 ...

※ How to calibrate Vibration meter

Most acceleration sensors are unstable and weakened easily, so that calibration is required.

① Go calibrate menu.

② Shake your device as possible as you can. Increase / decrease its sensitivity so that max value reaches about 10-11.

③ Check your unnecessary value measured by no movement.
④ Click the [Cut Baseline] button and select an number.

⑤ Repeat ②-④ several times.



Ⅲ. Lux Meter
Does your phone have a light sensor? This tool uses your light sensor to measures the ambient brightness. It is used to adjust the lighting required for plants or to check the brightness of a study room.

※ Main screen
This app shows the original/calibrated value, maximum, average and minimum.

① Refresh
② Alarm : You can select its threshold in the settings.
③ Y-axis range : Select the Y range of the chart (100, 250, 500, 1k, 2.5k, 10k, auto)

※ Point to the light source

For accurate measurement, make sure that your screen with the sensor is facing the  light source such as the sun, sky, window, lamp or candle. An actual light meter has a large convex sensor, so it has a wide range of exposures. Meanwhile, the embedded sensor on smart devices has a narrow range.

※ How to calibrate?

Go menu > calibration. Select factor option, and enter your own calibration value (range : 40 - 400%).

For example, measured value (200 lx) vs. expected value (300 lx) : select 150%. 

X. etc

※ FAQ
Q. It says "Unable to open microphone.".
A. Other app occupied your microphone. Just restart your device.

Q. Where can I find the Screenshot and CSV file?
A.  /storage/download/smart-tools/sound_xxxxxxxx_xxxxxx.csv

Q. I hear nothing. But the app shows 30-40 dB.
A. Most microphone cannot catch very low-frequency noise. 0 dB means the vacuum of space.

Q. Is the result dBA weighted?
A. Yes, I calibrated the app with an actual SPL meter with dBA. But db(A) makes no sense because the result is not perfect.

Q. How to disable tick sound switching from chart to text?
A. Turn off [Sound effect] option at the settings.

Q. What is the unit of vibration?
A. It has no unit, just the scale for reference.


※ What's new
 - v2.1.0 : Support for OS 14
 - v2.0 : Smart Meter Pro released (Oct. 2020)

https://play.google.com/store/apps/details?id=kr.aboy.meter

If you have any idea to improve it, feel free to contact me at androidboy1@gmail.com. Thank you.