Measured Environmental Values

Introduction

_images/sensorDescription.png

The Ambient 16 is a smarthome sensor measuring multiple physical measurements simultaneously. It is fitted with many sensing chips which physical values are combined and enhanced on an embedded microprocessor.

The nominal range of an Ambient 16 is a volume of 5x5x3 meters.

The physical quantities are measured through a sensitive face with a light bulge. The material used for the sensitive face is transparent to CO2 and must not be obstructed nor in contact with other materials and objects for optimal operation.

Note

The material of the sensitive face is delicate and can be subject to scratches. Handle it with care and avoid touching it. The sensitive face should only be cleaned with clear water. Avoid any soap or solvent as these could damage it.

The sensitive face is pierced with two apertures of 1x2 millimeters:

  • one is used for letting visible light through.

  • the other is placed in front of one of its temperature sensors for better contact with the ambient air and increase reactivity.

The power cable is made of a high quality rubber material similar to those used for high-end audio ear phones. It is tangle free and highly flexible with a very small curvature radius. The placement and arrangement of the cable is therefore extremely easy. The USB plug is a standard type A-plug. The sensor can be powered by any USB port and does not require high power (the nominal consumption is below 100 mA).

Note

The Ambient 16 is a sensitive device. Despite all the precautions we took in designing its internal power supply filters, low cost power supplies could trigger false events, essentially false motion detections. We are providing a slim power supply with low noise power as the ideal power source for our devices.

Temperature and humidity

The temperature range is from 0ºC to 50ºC. It is intended for indoor use only. Its precision is 0.1 ºC. The relative humidity range is 0 to 100 % with a precision of 5%.

The sensor has undergone a long calibration procedure in our lab. These calibration parameters will not vary with time.

The sensor’s ambient aire temperature is essentially measured through the front face. However, when placing the sensor or various materials, it could show variations of ± 1ºC. Its calibration is nominal for plaster, stones and wooden surfaces. Placed on highly conductive materials like marble or some metalic surfaces, it will measure temperatures lowered by 1ºC. Placed on isolating materials like fabric or felt, it will measure temperatures raised by 1ºC.

Note

In any home environment subject to draughts, with openings and many furnitures of heterogenous materials, measuring temperature with precision lower than 0.5ºC has no physical significance. For the same room, a sensor placed close to the ceiling or close to the floor might show differences of several degrees. Please refer to our placement guide for more information on real temperature signification, as for instance the best location for measuring temperature related to heating.

_images/heaterPlacement.jpg

Heats

Temperature is a physical parameter related to the quantity of heat stored in a material. Any material has a heat capacity. If heat would be water and the material a sponge, the heat capacity would tell how much water the sponge can contain. The heat conductivity is the ability of a material to transfer heat to another body. Keeping on with the sponge analogy, some sponges will absorb water very rapidly but cannot retain much (high conductivity, low capacity). Some mops will need more time to gather the water in an inundated bathroom but absorb more water (low conductivity, high capacity).

There are three ways of transfering heat:

  • by conduction, when two objects are in contact. Touch an object and you are giving or receiving heat by conduction.

  • by convection, through the flow of a fluid, typically an air draught. Wet your finger and put it in the wind. The cold sensation is the result of heat exchange by convection.

  • by radiation, through light. Typically feeling the Sunlight through a window on your face.

An Ambient 16 is calibrated such that it measures the ambient temperature of the air that surround it, placed on a surface like a brick wall or plaster. In these cases heat is exchanged by conduction, with the air and the wall.

But the Ambient 16 is also fitted with a light sensor that can tell the difference between artificial light and sunlight. It therefore can tell if energy in the room is dur to conduction or radiation. That takes a crucial importance for efficient energy regulation in households.

The Ambient 16 is also sensitive to draughts. However, there is no sensor inside for measuring wind speed. If you place the sensor in a passing doorway, you will see a lot of variations, probably due to convection. Place the same sensor in a quiet cornet of the same room, and the temperature will be much more stable.

Warning

At the time these lines are written (18/9/2020), the conductive/radiative percentage estimator is still in beta phase.

Condensation

Condensation happens when water vapor is converted it liquid vapor. It is a quite important aspect for home environment quality. Too much condensation can waeken masonry walls or cause mold growth. It also penalises energy use due to increased heat transfers. It is therefore important to monitor condensation, especially in new durable habitat where air exchange with the outdoor has been drastically reduced.

Combined with its air pressure sensor, the Ambient 16 is the ideal tool for exactly measuring the effect of water vapor in households.

Warning

Today, the condensation is only reported by the Ambient 16 as a dew point value. We are presently working with a University Lab for computing a more significant estimator as part of a more global air quality estimator.

InfluxDB storage

series

measurement

unit

description

temperature

calibratedValue_celcius

ºC

ambient air temperature

temperature

trend

ºC/hour

variation of temperature per hour

dewpoint

calibratedValue

ºC

dew point

saturatingvapor

calibratedValue

mbar

saturating vapor

humidity

calibratedValue

%

relative humidity

humidity

trend

%/hour

variation of relative humidity

heatTransfer

conductive

W

% of conductive heat transfer (beta)

heatTransfer

radiative

W

% of radiative heat transfer (beta)

MQTT events

series

event

description

temperature

variationEvent

temperature is varying

temperature

inRangeDetected

temperature is in user defined range

temperature

overRangeDetected

temperature is over user defined range

temperature

underRangeDetected

temperature in under user defined range

humidity

variationEvent

humidity is varying

humidity

inRangeDetected

humidity is in user defined range

humidity

overRangeDetected

humidity is over user defined range

humidity

underRangeDetected

humidity in under user defined range

Atmospheric pressure

Air pressure is measured in the range of 800 to 1 084 hPa. By default, the air pressure does not take the altitude into account.

Once the altitude has been provided to the sensor, the sensor provides the sea level air pressure.

InfluxDB storage

series

measurement

unit

description

airpressure

calibratedValueSeaLevel

mbar

atmospheric pressure at sea level

airpressure

rawValue

mbar

local atmospheric pressure

MQTT events

series

event

description

airpressure

inRangeDetected

atmospheric pressure is in user defined range

airpressure

overRangeDetected

atmospheric pressure is over user defined range

airpressure

underRangeDetected

atmospheric pressure in under user defined range

Carbon dioxide

CO2 quantities are measured between 440 amd 3000 ppm. Over 3000 ppm, values are still provided but not with an accuracy of 50ppm. Below 440 ppm, you are not living on Earth.

The Ambient 16 uses a dual channel non dispersive infrared sensor (NDIR). It measures the light attenuation at 4.26µm as a presence of CO2 . An additional wavelength at 3.91µm is measured as a reference value for taking into account dust and aging effects. The Ambient 16 is calibrated once and for all in our lab and does not need regular fresh air calibration.

The Ambient 16 provides accurate CO2 concentrations values for temperatures between 0ºC and 50ºC.

Usual carbon dioxide concentrations in househoulds

Concentration

Effect

440 to 1000 ppm

Standard concentrations in well ventilated homes

1000 to 2000 ppm

Poor air quality and drowsiness

2000 to 5000 ppm

Headaches, sleepiness, loss of attention

InfluxDB storage

series

measurement

unit

description

co2

calibratedValue

ppm

carbon dioxid concentration

co2

trend

ppm/hour

carbon dioxid concentration variation

MQTT events

series

event

description

co2

variationEvent

temperature is varying

co2

inRangeDetected

temperature is in user defined range

co2

overRangeDetected

temperature is over user defined range

co2

underRangeDetected

temperature in under user defined range

Light

Light intensity is measured in lux in a range of 0lx to 100000lx. Light color is provided as a temperature value in degrees Kelvin. Raw sensor values are also provided for red, green blue and intensity, between 0 and 65535. Beside light intensity and color, the Ambient 16 performs a complex analysis on the light spectrum and also gives the probability of a light to be natural or artificial. As an indication, the Sun altitude and azimuth is also part of the light information.

Two other estimators computed during the light spectrum analysis are available. They refer to the light intensity and color variability. These estimators are useful for detecting particular activities like TV, fire places among many other situations.

Indicative artificial light kind depending on temperature

Temperature in K

Light type

1700 - 1850

Match flame, low pressure sodium lamps

1850 - 2400

Candle flame

2100 - 2300

sodium light

2400 - 2550

Standard incandescent lamps

2550 - 2700

Soft white incandescent lamps

2700 - 3000

Soft white compact fluorescent or LED lamps

3000 - 3200

Warm white compact fluorescent or LED lamps

3200 - 3500

Quartz light, warm metal halide

3200 - 3350

Studio lamps, photofloods, Tungsten

3350 - 4100

Studio projector light

4100 - 5000

Fluorescent light

5000 - 5500

Tubular fluorescent lamps or cool white / daylight compact fluorescent lamps

5500 - 6200

Electronic flash

5900 - 6100

Mercury vapor light

6200 - 6500

Xenon short-arc lamp

6500 - 10500

LCD or CRT screen

Indicative natural light kind depending on temperature

Temperature in K

Light type

1850 - 2400

Sunset

1850 - 2400

Sunrise

4100 - 4150

Moonlight

5000 - 5500

Horizon daylight

5500 - 6500

Vertical daylight

6500 - 8000

Daylight, overcast

8000 - 10000

Daylight, partly clouded

10000 - 27000

Clear blue poleward sky

InfluxDB storage

series

measurement

unit

description

light

redRawValue

none

red intensity as provided by the sensor

light

greenRawValue

none

green intensity as provided by the sensor

light

blueRawValue

none

blue intensity as provided by the sensor

light

intensityRawValue

none

clear intensity as provided by the sensor

light

intensity

lux

calibrated light intensity

light

temperature

K

light temperature

ephemeris

sunAltitude

º

Sun altitude

ephemeris

sunAzimuth

º

Sun azimuth

light

intVar

none

variability of light intensity

light

colVar

none

variability of light color

light

lightOnDetected

boolean

light is on

light

lightOffDetected

boolean

light is off

light

darknessDetected

boolean

darkness has been detected

light

sunLightDetected

%

probability of Sun light

light

artificialLight

%

probability of artificial light

MQTT events

series

event

description

light

lightsOffEvent

total obscurity detected

light

lightsOnEvent

out of darkness event

light

shutterUpEvent

shutters openning detected (beta)

light

shutterDowndEvent

shutters closing detected (beta)

light

artificialLight

artificial light detected

light

naturalLight

natural light detected

light

sunLightDetected

Sun light detected

light

moonLightDetected

Moon light detected

light

directSunLightDetected

direct Sun light on the Ambient 16

light

darknessDetected

darkness detected

light

inRangeDetected

light in user defined range

light

overRangeDetected

light over user defined range

light

underRangeDetected

light under user defined range

Sound

Sound levels are reported in decibels, in both dBA and dBC units. The range is between 30dBA and 100dBA, and between 60dBC and 110dBC.

The A and C letters refer to different weighting, or importance, applied to the frequency spectrum. The dBA sound level applies to the mid-range frequencies. The dBC sound level measures low and high frequencies. The A-weighting measures the risk of hearing loss. The C-weighting is used for designing hearing protectors and the noise reduction rating calculations.

The Ambient 16 has a high sound level perception electronics. It is excellent a detecting low noises. A silence quality is available in its data payload. To achieve that, the signal from the sensor is distorted and filtered for lower frequencies. The sensor is, by design, not able to be used for voice recording and voice detection or identification. This has been certified by SGS during a privacy audit of the Ambient 16. So whatever software is running on the Ambient 16, no voice identification can be achieved due to the electronics design deliberate limitations.

Warning

The Ambient 16 is nevertheless computing a sound spectrogram on these tethered signals. In the future this spectrogram will be used for sound identification. Presently, this feature in in beta phase. We need more time, and essentially more training data, for being able to identify accurately sound types, like dog bark or baby cries. We have quite good success on identification right now, that for our 1000 sounds database. But we feel it is not robust enough to be put in the hands of users … or may be only for those who are ready to experiment with us. (19/8/2020).

InfluxDB storage

series

measurement

unit

description

sound

calibratedValue_dBA

dBA

sound level in decibel with A-weighting

sound

calibratedValue_dBC

dBC

sound level in decibel with C-weighting

sound

silenceQuality

%

quality of silence

sound

soundVariability

none

variability of sound

MQTT events

series

event

description

sound

silenceDetected

silence has been detected

sound

noiseDetected

noise has been detected

sound

inRangeDetected

sound level in user defined range

sound

overRangeDetected

sound level over user defined range

sound

underRangeDetected

sound level under user defined range

Motion and presence

The Ambient 16 detects human motion in a cone of view of 90º. It does not only report motion occurences but as well direction, speed, distance range and motion kind. This is achieved with special optics, electronics and a high gain PIR sensor especially made for us.

Speed and distance range have a low precision. These are rather indications like slow/walk/run and close (1 - 2 meters), mid range (2 - 4 meters) and far (beyond 5 meters).

Because of its very high gain, the Ambient 16 can detect very small motions. An event is not generated for every motion detected as this would be too frequent. Motion events are triggered for large motions like someone passing by, sitting or laying. But small motions, like those we do in front of TV, typing on a computer or sleeping are well reported as motion quantity in the data payload. This estimator is particularly useful for detecting activity kinds.

_images/motionDescription.png

The Ambient 16 provides a presence probability based on motion and sound. The physical presence is not one of its primary measurement, but a presence probability can be reconstructed. This is not a 100% certainty, all the time, but a very good indicator of room usage.

InfluxDB storage

series

measurement

unit

description

motion

motionQuantity

none

the quantity of motion observed by the sensor

motion

presenceProbability

%

probability of human presence

motion

type

enum

an enumeration describing the type of motion

motion

speed

enum

an enumeration describing the speed of motion

motion

direction

enum

an enumeration describing the direction of motion

motion

distance

enum

an enumeration describing the range of motion

MQTT events

series

event

description

motion

start_detected

motion is starting

motion

start_LR_detected

motion from left to right is starting

motion

start_RL_detected

motion from right to left is starting

motion

stop_detected

motion has stopped

Vibrations, motions and taps

The Ambient 16 reports vibrations and motions. This is for instance useful to detect fridge door openings or the vibrations of a washing machine. It also reports tap and double tap events on the front face or knocks on the surface close to it.

InfluxDB storage

series

measurement

unit

description

accelerometer

motionQuantity

none

the quantity of motion observed by the sensor

accelerometer

deviceTap

enum

taps detected

MQTT events

series

event

description

accelerometer

motionDetected

the device is being moved

accelerometer

userMotionDetected

the device is being moved over a user defined level

accelerometer

tapDetected

single tap or knock detected

accelerometer

doubleTapDetected

double tap or knock detected

Attitude

The Ambient 16 position in space is available as:

  • portrait up

  • portrait down

  • landscape left

  • landscape right

  • facing up

  • facing down

It also reports two angles with respect to the vertical and horizontal axis.

_images/sensorOrientation.png
InfluxDB storage

series

measurement

unit

description

accelerometer

deviceAttitude

enum

the attitude of the sensor in space

accelerometer

anglePhi

º

the phi angle with respect to the vertical

accelerometer

angleTheta

º

the theta angle with respect to the vertical

MQTT events

series

event

description

accelerometer

attitudeChangeDetected

device attitude has changed

Summary

InfluxDB storage

series

measurement

unit

description

temperature

calibratedValue_celcius

ºC

ambient air temperature

temperature

trend

ºC/hour

variation of temperature per hour

dewpoint

calibratedValue

ºC

dew point

saturatingvapor

calibratedValue

mbar

saturating vapor

humidity

calibratedValue

%

relative humidity

humidity

trend

%/hour

variation of relative humidity

heatTransfer

conductive

W

% of conductive heat transfer (beta)

heatTransfer

radiative

W

% of radiative heat transfer (beta)

airpressure

calibratedValueSeaLevel

mbar

atmospheric pressure at sea level

airpressure

rawValue

mbar

local atmospheric pressure

co2

calibratedValue

ppm

carbon dioxid concentration

co2

trend

ppm/hour

carbon dioxid concentration variation

light

redRawValue

none

red intensity as provided by the sensor

light

greenRawValue

none

green intensity as provided by the sensor

light

blueRawValue

none

blue intensity as provided by the sensor

light

intensityRawValue

none

clear intensity as provided by the sensor

light

intensity

lux

calibrated light intensity

light

temperature

K

light temperature

light

intVar

none

variability of light intensity

light

colVar

none

variability of light color

light

lightOnDetected

boolean

light is on

light

lightOffDetected

boolean

light is off

light

darknessDetected

boolean

darkness has been detected

light

sunLightDetected

%

probability of Sun light

light

artificialLight

%

probability of artificial light

ephemeris

sunAltitude

º

Sun altitude

ephemeris

sunAzimuth

º

Sun azimuth

sound

calibratedValue_dBA

dBA

sound level in decibel with A-weighting

sound

calibratedValue_dBC

dBC

sound level in decibel with C-weighting

sound

silenceQuality

%

quality of silence

sound

soundVariability

none

variability of sound

motion

motionQuantity

none

the quantity of motion observed by the sensor

motion

presenceProbability

%

probability of human presence

motion

type

enum

an enumeration describing the type of motion

motion

speed

enum

an enumeration describing the speed of motion

motion

direction

enum

an enumeration describing the direction of motion

motion

distance

enum

an enumeration describing the range of motion

accelerometer

motionQuantity

none

the quantity of motion observed by the sensor

accelerometer

deviceTap

enum

taps detected

accelerometer

anglePhi

º

the phi angle with respect to the vertical

accelerometer

angleTheta

º

the theta angle with respect to the vertical

accelerometer

deviceAttitude

enum

the attitude of the sensor in space

MQTT events

series

event

description

temperature

variationEvent

temperature is varying

temperature

inRangeDetected

temperature is in user defined range

temperature

overRangeDetected

temperature is over user defined range

temperature

underRangeDetected

temperature in under user defined range

humidity

variationEvent

humidity is varying

humidity

inRangeDetected

humidity is in user defined range

humidity

overRangeDetected

humidity is over user defined range

humidity

underRangeDetected

humidity in under user defined range

airpressure

inRangeDetected

atmospheric pressure is in user defined range

airpressure

overRangeDetected

atmospheric pressure is over user defined range

airpressure

underRangeDetected

atmospheric pressure in under user defined range

co2

variationEvent

temperature is varying

co2

inRangeDetected

temperature is in user defined range

co2

overRangeDetected

temperature is over user defined range

co2

underRangeDetected

temperature in under user defined range

light

lightsOffEvent

total obscurity detected

light

lightsOnEvent

out of darkness event

light

shutterUpEvent

shutters openning detected (beta)

light

shutterDowndEvent

shutters closing detected (beta)

light

artificialLight

artificial light detected

light

naturalLight

natural light detected

light

sunLightDetected

Sun light detected

light

moonLightDetected

Moon light detected

light

directSunLightDetected

direct Sun light on the Ambient 16

light

darknessDetected

darkness detected

light

inRangeDetected

light in user defined range

light

overRangeDetected

light over user defined range

light

underRangeDetected

light under user defined range

sound

silenceDetected

silence has been detected

sound

noiseDetected

noise has been detected

sound

inRangeDetected

sound level in user defined range

sound

overRangeDetected

sound level over user defined range

sound

underRangeDetected

sound level under user defined range

motion

start_detected

motion is starting

motion

start_LR_detected

motion from left to right is starting

motion

start_RL_detected

motion from right to left is starting

motion

stop_detected

motion has stopped

accelerometer

motionDetected

the device is being moved

accelerometer

userMotionDetected

the device is being moved over a user defined level

accelerometer

tapDetected

single tap or knock detected

accelerometer

doubleTapDetected

double tap or knock detected

accelerometer

attitudeChangeDetected

device attitude has changed