NoiseMeter
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| Project NoiseMeter | |
|---|---|
| File:NoiseMeter.jpg | |
| Measuring audio noise as citizen science | |
| Status | Initializing |
| Contact | bertrik |
| Last Update | 2024-04-25 |
Introduction
This project is about measuring environmental audio noise as citizen science.
For example, noise can be:
- road traffic noise (cars, mopeds, etc)
- air traffic noise,
- industrial noise, like building activities
Existing sound/noise meter projects:
- DNMS project by Helmut Bitter
- LoRa sound kit by Marcel Meek, ESP32 with I2S microphone, shares many concepts with EspAudioSensor
- LoRaWAN PM/Sound sensor by Bas van Drunen, shares many concepts with LoraWanDustSensor
- Amsterdam sounds kit from Waag Society,
- Unknown sensor tested by RIVM in Schiedam (mentioned on https://www.samenmetenaanluchtkwaliteit.nl/nieuws/citizen-science-geluidmetertest-op-rivm-terrein )
- Sound meter by Bart Jurgens uit Amerongen, link ???
This project page considers a kind of clone of the Amsterdam Sounds project.
Other interesting stuff:
- My brother looked inside three inexpensive sound meters: https://twitter.com/jrsikken/status/1779225176464392685
Hardware
Nano33 IOT
Hardware is a nano33 iot board.
| SPH0645 | nano33 iot | Remark |
|---|---|---|
| SEL | - | leave unconnected |
| LRCK | A2 (16) - I2S FS | sample clock |
| DOUT | D4 (4) - I2S SD | data |
| BCLK | A3 (17) - I2S SCK | bit clock |
| GND | GND | |
| 3V | 3v3 |
Software
The software is based on Arduino, a kind of clone of the Amsterdam Sounds project, modified to use WiFi (instead of LoRa), written by Rene Kuijf.
My modifications consist of a platformio configuration, for easy building.
See AdamSoundsInflux-slim-nano-33 github repo for the source code.
Casing
Microphone protection
To protect the microphone, use a membrane, like:
Junction box
Simple junction boxes sold by Gamma:
- https://www.gamma.nl/assortiment/attema-kabeldoos-m20-met-3-wartels-ip65/p/B410376 and
- https://www.gamma.nl/assortiment/attema-kabeldoos-ip65-3x-m25-m20/p/B306878 (IP65)
A downward pointing hole can be used for an 868 MHz LoRaWAN antenna.
Sensor.community casing
See https://sensor.community/docs/dnms/dnms-noise-measuring-dn40-result.jpg
Dimensions:
- microphone is on a half inch (12.7 mm OD) white polystyrene pipe, 115 mm long
- main piece is 25mm, length 160mm
- some other connecting piecess
"RIVM" test casing
Exact dimensions unknown, see photo on this page: https://samenmeten.nl/nieuws/citizen-science-geluidmetertest-op-rivm-terrein
My guess:
- microphone is on a 10mm diameter pipe, length 100mm
- main case is a 40mm diameter pipe, length 200mm
Experiments
Uni-T UT353 BT noise meter
This thing has bluetooth.
serial interface
Interpreting serial port data on Linux is not straightforward, since Linux treats a serial port as a terminal so by default it does terminal-specific stuff to the data. The data below may have been corrupted by the Linux tty subsystem trying to escape/unescape certain byte sequences.
There is an internal serial interface (9600 bps). Use the following to configure the serial port on linux
stty -F /dev/ttyUSB0 raw 9600 -echo
Then dump using
cat /dev/ttyUSB0 |hexdump -C
When in bluetooth mode, there is data going over this interface:
01 fc 12 13 aa bb 10 05 3b 20 20 34 34 2e 31 64 42 41 3d 34 00 04 14 01 fc 12 13 aa bb 10 05 3b 20 20 34 30 2e 34 64 42 41 3d 34 00 04 13 01 fc 12 13 aa bb 10 05 3b 20 20 33 39 2e 30 64 42 41 3d 34 00 04 17 01 fc 12 13 aa bb 10 05 3b 20 20 33 38 2e 35 64 42 41 3d 34 00 04 1b 01 fc 12 13 aa bb 10 05 3b 20 20 33 38 2e 34 64 42 41 3d 34 00 04 1a 01 fc 12 13 aa bb 10 05 3b 20 20 33 38 2e 38 64 42 41 3d 34 00 04 1e 01 fc 12 13 aa bb 10 05 3b 20 20 33 39 2e 31 64 42 41 3d 34 00 04 18 01 fc 12 13 aa bb 10 05 3b 20 20 33 38 2e 39 64 42 41 3d 34 00 04 1f 01 fc 12 13 aa bb 10 05 3b 20 20 33 39 2e 35 64 42 41 3d 34 00 04 1c 01 fc 12 13 aa bb 10 05 3b 20 20 33 39 2e 32 64 42 41 3d 34 00 04 19
Dividing into "frames", starting with 01 fc 12 aa bb:
01 fc 12 13 aa bb 10 05 3b 20 20 34 34 2e 31 64 42 41 3d 34 00 04 14 => "44.1dBA"
01 fc 12 13 aa bb 10 05 3b 20 20 34 30 2e 34 64 42 41 3d 34 00 04 13 => "40.4dBA"
<---------header--------->
01 fc 12 13 aa bb 10 05 3b
<------------ascii------->
X X . X d B A
<--- footer-->
3d 34 00 04 ??
3d 34 XX 04 YY
^--- ????
^--- is 34 in slow mode, 33 in fast mode
^--- is 1 in hold mode, 0 in normal mode
^--- always 04
^--- varies between 10, 11, 12, 13, 14, 15, 16, 17, 19, 1B
<pre>
Each frame is 23 (x017) bytes long
==== BLE interface ====
This thing has a bluetooth interface.
FCC report on the bluetooth part: https://fcc.report/FCC-ID/2AWEE-8762-01/4740558
In short, as I interpret the BLE configuration:
* a "Generic Attribute Profile" service, like all BLE devices have
* a service related to bluetooth parameters, also looks fairly standard, and not related to the measurements themselves
* a "Device information" service
* a custom vendor-specific service, where I suspect the noise-meter specific data is
In raw format:
* <b>service 00001801-0000-1000-8000-00805f9b34fb: Generic Attribute Profile</b>
** ...
* <b>service: 0000ff12-0000-1000-8000-00805f9b34fb: Unknown</b>
** characteristic: 0000ff01-0000-1000-8000-00805f9b34fb Unknown
*** descriptor: 00002901-0000-1000-8000-00805f9b34fb Characteristic User Description "Data In"
** characteristic: 0000ff02-0000-1000-8000-00805f9b34fb Unknown
*** descriptor: 00002902-0000-1000-8000-00805f9b34fb Client Characteristic Configuration
*** descriptor: 00002901-0000-1000-8000-00805f9b34fb Characteristic User Description "Data Out"
** characteristic: 0000ff03-0000-1000-8000-00805f9b34fb Unknown
*** descriptor: 00002901-0000-1000-8000-00805f9b34fb Characteristic User Description "Baud Rate"
** characteristic: 0000ff04-0000-1000-8000-00805f9b34fb Unknown
*** descriptor: 00002901-0000-1000-8000-00805f9b34fb Characteristic User Description "Link Interval"
** characteristic: 0000ff05-0000-1000-8000-00805f9b34fb Unknown
*** descriptor: 00002901-0000-1000-8000-00805f9b34fb Characteristic User Description "Pair code"
** characteristic: 0000ff06-0000-1000-8000-00805f9b34fb
*** descriptor: 00002901-0000-1000-8000-00805f9b34fb "BT Name"
** characteristic: 0000ff07-0000-1000-8000-00805f9b34fb
*** descriptor: 00002901-0000-1000-8000-00805f9b34fb "Pair Code En"
** characteristic: 0000ff08-0000-1000-8000-00805f9b34fb
*** descriptor: 00002901-0000-1000-8000-00805f9b34fb "Adv interval"
** characteristic: 0000ff09-0000-1000-8000-00805f9b34fb
*** descriptor: 00002901-0000-1000-8000-00805f9b34fb "TX Power"
** characteristic: 0000ff0a-0000-1000-8000-00805f9b34fb
*** ... "MCU Delay"
** characteristic: 0000ff0b-0000-1000-8000-00805f9b34fb
*** ... "Mode Control"
** characteristic: 0000fff0-0000-1000-8000-00805f9b34fb
*** ... "Factory Set"
** characteristic: 0000fff1-0000-1000-8000-00805f9b34fb
*** descriptor: 00002901-0000-1000-8000-00805f9b34fb "Reset"
* <b>service: 0000180a-0000-1000-8000-00805f9b34fb Device Information</b>
** ...
* <b>service: 0000d0ff-3c17-d293-8e48-14fe2e4da212 Vendor specific</b>
** characteristic: 0000ffd1-0000-1000-8000-00805f9b34fb Write
** characteristic: 0000ffd2-0000-1000-8000-00805f9b34fb Read, typically 40C1F6049BD7
** characteristic: 0000ffd3-0000-1000-8000-00805f9b34fb Read, typically 01901468
** characteristic: 0000ffd4-0000-1000-8000-00805f9b34fb Read, typically 21100048
** characteristic: 0000ffd5-0000-1000-8000-00805f9b34fb Read, typically ...?
** characteristic: 0000ffd8-0000-1000-8000-00805f9b34fb Write
** characteristic: 0000fff1-0000-1000-8000-00805f9b34fb Read, typically 0501000700080000F00F0000
** characteristic: 0000fff2-0000-1000-8000-00805f9b34fb Write
** characteristic: 0000ffe0-0000-1000-8000-00805f9b34fb Read, typically 00 00 00 01 01 00 00 00 01 90 14 68 21 10 00 48