Air Quality Station Node

Hardware description

The Air Quality Station Node is composed of several parts:

  • Air Quality Station Core

  • Air Quality Station Sensor Cartridge

  • Air Quality Station Temperature and Humidity SHT35 sensor probe

  • Optional sensors:

    • Particulate Matter

    • Weather station

    • Noise level

The next table shows the device features:

Feature

Description

Dimensions

271 x 170 x 120 mm

Power supply

110-240 VAC, 50/60 Hz 60 W

Backup battery

2200 mAh, Li-SOCl2 battery

Loop time

1, 2, 3, ... 60 min (5 min default)

Radio protocol

LTE / LoRaWAN

LTE provisioning

APN settings to be configured via USB port

LoRaWAN provisioning

Communication mode to be configured via USB

(default keys and EUI are already preconfigured in the node)

Node configuration

Via "Smart Devices App" (Java desktop app)

Remote configuration

Via Libelium's Services Cloud Manager (OTA and remote parameters configuration)

Operating temperature

-30 ºC to +40 ºC

Market certifications

CE (Europe) and FCC (USA)

Firmware description

The Air Quality Station node manages 3 different firmwares:

  • Bootloader: It is used to load the application or golden firmware when the device is powered on. Also, the bootloader performs Over The Air programming tasks.

  • Application firmware: It is the main firmware which sets up the device's peripherals (communication and sensors) and then performs an infinite loop consisting on measuring, sending and waiting in idle state to start a new loop.

  • Golden firmware: It is a backup firmware in case of fatal error during OTA process. Its purpose is exactly the same as the "Application firmware" but in a different flash memory position to avoid the device from freezing.

Air Quality Station Core

The core of the device includes:

  • Enclosure

  • Main PCB, which includes an atmospheric pressure sensor and communication modules

  • Antennas

  • External sensors sockets

  • External LED for pattern visualization

  • Nano-SIM + Micro-USB socket

Core of the device (also includes the sensor cartridge)

Enclosure and stickers

The enclosure consists of few parts, so it can be easily mounted by hand. You can open it by means of a screwdriver. When opening the enclosure, it permits a hinged side if required for better management.

PC UL 94 V0 material is suitable for outdoor use (f1 listing acc. to UL 746C and corresponds to requirements set R 22 acc. to DIN EN 45545-2 of hazard level HL3).

Enclosure

The enclosure comes along with wall brackets to provide an easy installation procedure. They are screwed into the drilling holes on the back of the enclosure base. Wall brackets can also be used to attach flanges and install the device on a different structure as a street lamp or similar.

Wall brackets
Wall brackets screwed on the base of enclosure

Sticker

In the back side of the enclosure you can find the sticker with the description of the device. It includes the unique Serial ID of the device, the preconfigured LoRaWAN EUI and the LTE module's IMEI.

Sticker with technical details

Socket description

The next image describes how the external sensors are plugged into the enclosure:

Air Quality Station bottom side distribution

Nano-SIM + Micro-USB socket

The nano-SIM card socket allows the user to insert the SIM card needed for LTE communications. It is not necessary to send a SIM card to Libelium for proper installation. Besides, the nano-SIM card connector has a push-pull mechanism, so it is easy to remove the card with the aid of one nail.

Nano-SIM card (4FF standard size)

The same socket provides the micro-USB connection. This is intended for in situ parameter configuration purposes or firmware upgrades. These USB operations shall be performed using the Smart Devices App, which is a desktop application.

Nano-SIM + Micro-USB socket

Please mind the correct orientation of the nano-SIM card: the side of the chip must look towards the micro-USB connector, and the 45º-angled corner must face the device

LTE

The LTE Cat 4 module delivers maximum data rates of up to 150 Mbps for downlink and 50 Mbps for uplink. It is backward-compatible with existing EDGE and GSM/GPRS networks, ensuring that it can be connected even in remote areas devoid of 4G or 3G coverage.

Air Quality Station 4G radio

Frequency

Bands

LTE-FDD

B1/B2/B3/B4/B5/B7/B8/B12/B13/B18/B19/B20/B25/B26/B28

LTE-TDD

B38/B39/B40/B41

WCDMA

B1/B2/B4/B5/B6/B8/B19

Region

Global

The LTE module is the default communication method in order to send data values to the Libelium Services Cloud Manager. Remote configuration and OTA programming are done via LTE module.

The device's firmware is prepared to automatically send data to the Cloud, so the only parameters that must be set by the user are:

  • APN

  • Login

  • Password

  • SMS password

  • SIM's PIN

  • SIM's PUK

To know how to configure LTE parameters, please refer to the "Smart Devices App" section

SMS commands

It is possible to send commands to the node via SMS. The format of the text message must be formed by a "command" and then the "SMS password" configured in the device via Smart Devices App. By default, the SMS password is "12345678". Finally there might be an optional value depending on the command used. All these fields are separated by a space character:

<command> <sms_password> [<value>]

Command

Description

keepalive

It queries the device to answer with an SMS advertising it is still working

reboot

It queries the device to answer with an SMS describing it is about to reboot and then reboots.

password

It sets a new SMS password set in the node

Examples:

keepalive 12345678

reboot 12345678

password 12345678 87654321

LoRaWAN

This product provides a LoRaWAN module although the LTE module is the default communication protocol. LoRaWAN is a Low Power Wide Area networking protocol (LPWAN) designed to send data at low data rates.

Air Quality Station LoRaWAN radio

LoRaWAN network architecture is deployed in a star-of-stars topology in which gateways relay messages between end-devices and a central network server.

Keep in mind that some vital features are only available with 4G communications, like OTA, rich remote management and advanced security. The reason is the inability of the LoRaWAN protocol to transmit large volumes of data.

LoRaWAN gateway

The LoRaWAN gateways (also known as LoRaWAN base stations) are connected to the LoRaWAN network server via standard IP connections and act as a transparent bridges. They simply convert RF packets into IP packets and vice-versa.

LoRaWAN network server

The LoRaWAN network server connects to Libelium's Services Cloud Manager where raw data will be parsed, treated by algorithms and stored for later use.

The LoRaWAN network servers currently supported by our Services Cloud Manager for Air Quality services are:

LoRaWAN regions

This product supports the next LoRaWAN regional protocols:

Channel plan

Common name

Region

EU 863-870 MHz

EU868

Europe

US 902-928 MHz

US915

United States

AU 915-928 MHz

AU915

Australia

IN 865-867 MHz

IN865

India

AS 923 MHz

AS923

Asia

KR 920-923 MHz

KR920

South Korea

For further information about the LoRaWAN regional parameters, please refer to the LoRa Alliance's official resources: https://lora-alliance.org/resource_hub/rp2-102-lorawan-regional-parameters/

LoRaWAN parameters

This product only features LoRaWAN OTAA mode to join the LoRaWAN network server. ABP mode is not currently permitted.

The configurable LoRaWAN parameters are:

  • Device EUI: Read/write, 8-byte identifier configured into the LoRaWAN module to be used as operating identifier.

  • Application EUI: It is an 8-byte application identifier. Needed for opening an OTAA session and exchange encryption keys.

  • Application Key: It is a 16-byte key. Needed for opening an OTAA session and exchange encryption keys.

  • ADR: Adaptive Data Rate setting which can be enabled or disabled. If ADR is enabled, the server will optimize the data-rate based on the information collected from the network: the RSSI / SNR of the last received packets.

  • Port: Port number used to send data. Range: 1 to 223.

  • Region:

    • AS923

    • AU915

    • EU868

    • KR920

    • IN865

    • US915

    • US915-HYBRID

  • Subband: In AU915 and US915 regions it is possible to enable different subbands:

    • Channels 0-7

    • Channels 8-15

    • Channels 16-23

    • Channels 24-31

    • Channels 32-39

    • Channels 40-47

    • Channels 48-55

    • Channels 56-63

To know how to configure LoRaWAN parameters please refer to "Smart Devices App" section

Air Quality Station Sensor Cartridge

The Sensor Cartridge is composed of the gas sensors, the PCB where these gas sensors are plugged and the outdoor protection enclosure. A 2200 mA·h backup battery is attached to the Sensor Cartridge in order to keep the power supply of the gas sensors in case of sudden electricity blackout. Therefore, when power supply is recovered, sensors have maintained their power supply without interruption and measurements are not affected by the electricity blackout.

Air Quality Station Sensor Cartridge

How to replace the Sensor Cartridge

In case of replacement due to sensor deterioration, the Sensor Cartridge can be easily removed and replaced by other unit.

Step 1: Open the enclosure.

Step 2: Remove the 2 wires that connect the main core board to the Sensor Cartridge board.

Step 3: Remove the 4 external screws that fix the Sensor Cartridge to the enclosure.

Step 4: Remove the old Sensor Cartridge and place the new one in the same position.

Step 5: Undo the first steps by fixing the cartridge with the 4 screws and connecting the 2 connection wires. Finally, close the enclosure.

Gas sensors

CO - Carbon monoxide sensor

Performance

Value

Sensitivity

420 to 650 nA/ppm at 2 ppm CO

Response time

<25 s from zero to 10 ppm CO

Zero current

+ 30 to -130 nA in zero air at 20ºC

Noise

4 ppb

Range

1000 ppm limit of performance warranty

Linearity

20 to 35 ppb CO error at full scale, linear at zero, 500 ppm CO

Temperature range

-30 to 50 ºC

Humidity range

15 to 90 %RH continuous

O3 - Ozone sensor

Performance

Value

Sensitivity

-225 to -750 nA/ppm at 1 ppm O3

Response time

<80 s from zero to 1 ppm O3

Zero current

-80 to +80 nA in zero air at 20ºC

Noise

15 ppb

Range

20 ppm limit of performance warranty

Linearity

< +/- 0.5 ppm error at full scale, linear at zero and 20 ppm O3

Temperature range

-30 to 40 ºC

Humidity range

15 to 85 %RH continuous

SO2 - Sulfur dioxide sensor

Performance

Value

Sensitivity

275 to 475 nA/ppm at 2 ppm SO2

Response time

<40 s from zero to 2 ppm SO2

Zero current

-80 to +80 nA in zero air at 20ºC

Noise

5 ppb

Range

100 ppm limit of performance warranty

Linearity

0 to -2 ppb error at 100 ppm SO2, linear at zero and 10 ppm SO2

Temperature range

-30 to 50 ºC

Humidity range

15 to 90 %RH continuous

NO - Nitric oxide sensor

Performance

Value

Sensitivity

500 to 850 nA/ppm at 2 ppm NO

Response time

<45 s from zero to 2 ppm NO

Zero current

30 to 140 nA in zero air at 20ºC

Noise

15 ppb

Range

20 ppm limit of performance warranty

Linearity

< +/- 1 ppb error at full scale, linear at zero and 5 ppm NO

Temperature range

-30 to 40 ºC

Humidity range

15 to 85 %RH continuous

NO2 - Nitrogen dioxide sensor

Performance

Value

Sensitivity

-200 to -650 nA/ppm at 2 ppm NO2

Response time

< 60 s from zero to 2 ppm NO2

Zero current

< 70 nA in zero air at 20ºC

Noise

15 ppb

Range

20 ppm limit of performance warranty

Linearity

< +/- 0.5 ppb error at full scale, linear at zero and 20 ppm NO2

Temperature range

-30 to 40 ºC

Humidity range

15 to 85 %RH continuous

Internal SHT35 sensor

The internal SHT35 sensor is installed within the Sensor Cartridge next to the gas sensors to track the ambient conditions the sensors are exposed to when the measurements are done.

Humidity specification

Parameter

Value

Accuracy tolerance

+/- 1.5 %RH

Resolution

0.01 %RH

Range

0 to 100 %RH

Long-term drift

<0.25 %RH/year

‌Temperature specification

Parameter

Value

Accuracy tolerance

+/- 0.1 ºC

Resolution

0.01 ºC

Range

-40 to 125 ºC

Long-term drift

<0.03 ºC/year

Air Quality Station Temperature and Humidity SHT35 sensor probe

The external Temperature and Humidity SHT35 sensor probe measures the air temperature and humidity. This external SHT35 sensor probe is mandatory as the values provided by the sensor are used by the algorithms that finally calculate the gas concentration on the Libelium's Services Cloud Manager.

Temperature and Humidity SHT35 sensor probe connected to an Air Quality Station node

Weather station (optional)

The device offers the possibility of connecting a MaxiMet weather station manufactured by Gill Instruments.

The MaxiMet series offers a compact solution for weather forecast. The user can choose the best configuration thanks to the modularity that they offer, keeping the robustness, easy installation and low maintenance features.

Parameters related with wind, precipitation, solar radiation, dew point, air temperature, air relative humidity or atmospheric air pressure can be measured with these weather station probes.

Available models:

Weather station

Wind and compass

Precipitation

Temperature, humidity and pressure

Solar radiation

GMX-240

Yes

Yes (only optical)

No

No

GMX-550

Yes

Optional (Tipping bucket accessory needed)

Yes

No

GMX-551

Yes

Optional (Tipping bucket accessory needed)

Yes

Yes

MaxiMet GMX-240 sensor probe

The MaxiMet GMX-240 is a weather station that provides accurate meteorological information about wind and precipitation (optical method).

Three ultrasonic sensors provide wind speed and direction measurements and the addition of an electronic compass provides apparent wind measurement. Average speed and direction together with WMO averages and gust data are also provided.

An integrated optical rain gauge that senses water hitting its outside surface provides measurements based on the size and number of drops.

The optical rain gauge and the wind ultrasonic sensors have no moving parts so possible mechanical problems are avoided.

MaxiMet GMX-240 sensor probe

Gill reports their optical precipitation sensor is valid for knowing if it rains. Compact and with low maintenance, it gives a general idea of the amount of rain, but it is not really accurate. Choose the Tipping Bucket for superior accuracy and reliability.

MaxiMet GMX-550 sensor probe

The MaxiMet GMX-550 sensor probe provides accurate information about wind, precipitation (with an accessory), air temperature, air humidity and atmospheric air pressure.

This model is basically a solar shield with no moving parts which allows high performance over large time periods. On the top of the solar shield, 3 ultrasonic sensors are placed to provide wind speed and direction measurements. Besides, an electronic compass provides apparent wind measurement. Average speed and direction together with WMO averages and gust data are also provided. Finally, an inclinometer is also included to allow a precise installation.

On top of that, an integrated connector allows the user to connect a tipping bucket rain gauge to measure precipitation.

MaxiMet GMX-550 sensor probe

MaxiMet GMX-551 sensor probe

The MaxiMet GMX-551 sensor probe provides accurate information about wind, precipitation (with an accessory), air temperature, air humidity, atmospheric air pressure and solar radiation.

This model is basically a solar shield with no moving parts which allows high performance over large time periods. On the top of the solar shield, 3 ultrasonic sensors are placed to provide wind speed and direction measurements. Besides, an electronic compass provides apparent wind measurement. Average speed and direction together with WMO averages and gust data are also provided. Additionally, an integrated pyranometer protected by a single glass measures the solar radiation. Finally, an inclinometer is also included to allow a precise installation.

On top of that, an integrated connector allows the user to connect a tipping bucket rain gauge to measure precipitation.

MaxiMet GMX-551 sensor probe

Noise level sensor (optional)

The Noise level sensor is a class 2 soundmeter. It complies with IEC 61672-1:2013, ANSI S1.4-1983 and ANSI S1.43-1997.

Attribute

Value

Range

25 to 136 dBA

Class

Class 2

Frequency range

20 Hz to 12.5 kHz

Normatives

GB/T3785.1-2010

GB/T3785.2-2010

IEC60651:1979

IEC60804:2000

IEC61672-1:2013

ANSI S1.4-1983

ANSI S1.43-1997

Indoor microphone

Microphone class 2

Sensitivity: 40 mV/PA

Frequency range: 20 Hz to 12.5 kHz

Socket: TNC

Power supply: ICCP Standard

Measurements available

LAeq, 1 min

Noise level sensor class 2

The Noise level has an optional weatherproof outdoor microphone. This microphone meets IEC 61672 class 1 specification. It is prepared for outdoor weather conditions (rain, wind, etc). It also provides a 2-meter extension cable, needed for a proper installation.

Outdoor microphone

Particle matter (optional)

Particulate matter is composed of small solid or liquid particles floating in the air. The origin of these particles can be the industrial activity, exhaust fumes from diesel motors, building heating, pollen, etc. These tiny particles enter our bodies when we breath. High concentrations of particle matter can be harmful for humans or animals, leading to respiratory and coronary diseases, and even lung cancer. That is why this is a key parameter for the Air Quality Index.

Particles are classified as follows:

  • PM1: Mass (in μg) of all particles smaller than 1 μm, in 1 m³.

  • PM2.5: Mass (in μg) of all particles smaller than 2.5 μm, in 1 m³.

  • PM10: Mass (in μg) of all particles smaller than 10 μm, in 1 m³.

Particle matter sensor

High humidity or foggy environments could affect the measures of the sensor. The particles can be swollen by or coated by water. This results in measures which are higher than in dry environments.

If high humidity, fog or mist are present, then the sensor will actually measure the water droplets in the air, causing very high readings.