DST ObservAir Manual de instruções - Página 11

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k. LEDmode: Pollution concentration data displayed using the LED

button in breathing mode. The LED can also be set to display only

sensor alerts, or be turned off completely. Options are 'BC', 'GAS1',

'GAS2', 'ALERT', or 'OFF'. Default setting is 'BC'.

LEDra: Running average, in seconds, applied to the pollution

concentration data displayed using the LED button. Lower running

average values provide higher time resolution but the LED color

display may fluctuate due to sensor noise, while higher running

average values provide a smoother display with lower time

resolution. Default setting is 90 seconds.

m. LEDmaxConc: Maximum concentration setting for the LED display.

Default is 5 µg/m

of BC (default LEDmode setting).

n. LEDtimeout: The time duration, in minutes, before which the LED

display turns off automatically. Default is 20 minutes.

o. maxATN: Maximum optical attenuation (ATN). When filter loading

is above this value, an alarm is triggered. Default is 80.

p. timeZone: Time zone in hours relative to GMT. For example, New

York is represented by "-4" (GMT- 4:00). Default is 0.

q. GPS: Optional GPS unit is logging when 'True' and powered off

when 'False'. Default is 'False'.

3. Factors:

This

field

contains

compensation factors for each pollutant species monitored onboard the

ObservAir unit. Most factors in this field are for DST's internal protocols,

but those pertinent to the end user are listed below:

a. MAC: Mass absorption coefficient for BC determination (see

Section 1.1.1). Default value is 12.5 m

b. FRcal: Flow rate calibration factor. Default value is 1.0.

c. Code1: Calibration code for the first optional gas sensor in units of

nA/ppm. Each gas sensing cell has a unique code from the

manufacturer (see Section 1.1.2).

d. Code2: Calibration code for the second optional gas sensor

(nA/ppm).

4. colNames: Names of the fields logged in the data file as they appear

on each line. For the base unit ObservAir, without gas sensing, the

following column names will be listed

a. TS: Timestamp in the format: YYYY-MM-DD HH:MM:SS

b. Iref: Reference intensity from the aerosol absorption photometer.

Value is expressed in terms of the ADC's raw count. Full scale value

is 8388607.

ObservAir Operating Manual

calibration

and

environmental

/g.

c. Isig: Signal intensity from the aerosol absorption photometer. Value

is expressed in terms of the ADC's raw count. Full scale value is

8388607.

d. ATN: Optical attenuation (unitless)

e. BC: Black carbon in µg/m

T: Temperature in ºC.

g. RH: Relative humidity in %.

h. FR: Sample flow rate in ccm.

VBAT: Battery voltage in volts.

If the unit has a single gas sensor onboard, the following columns will

be appended to those above:

a. GAS1: Gas concentration in ppm (except for NO

b. Vg_ref1: Reference output from electrochemical cell in volts.

c. Vg_sig1: Signal output from electrochemical cell in volts.

If the unit has two gas sensors onboard, the following columns will be

appended to those above:

a. GAS2: Gas concentration in ppm (except for NO

b. Vg_ref2: Reference output from electrochemical cell in volts.

c. Vg_sig2: Signal output from electrochemical cell in volts.

3.5.2. Data file

The ObservAir data is written in comma separated value (csv) format to a

.txt file. Each line in the file represents a datalogging event, and starts with

the character "$". Values are listed in the order provided in the colNames

field of the corresponding setting entry. Typical data output from a base

model ObservAir (without gas sensing) is shown below. If gas sensors are

fitted to the unit, the output data will be appended to each line in the order

listed in the colNames field.

$2020-09-15 23:21:26, 6889274, 7486915, 0.4477415,-0.5281, 37.70047, 32.93088, 99.6, 7.66

$2020-09-15 23:21:28, 6889416, 7487140, 0.4477730, 0.0924, 37.63485, 32.93088, 100.3, 7.66

$2020-09-15 23:21:30, 6889638, 7487262, 0.4473400, -1.2549, 37.52956, 32.91753, 100.3, 7.66

$2020-09-15 23:21:32, 6889808, 7487379, 0.4477415, 1.1772, 37.58144, 32.91753, 100.3, 7.66

$2020-09-15 23:21:34, 6890005, 7487519, 0.4491062, 4.0048, 37.62112, 32.93088, 100.3, 7.66

$2020-09-15 23:21:36, 6890185, 7487705, 0.4500246, 2.6575, 37.72641, 32.93088, 100.3, 7.66

$2020-09-15 23:21:38, 6890353, 7487792, 0.4502516, 0.6841, 37.72336, 32.91753, 100.3, 7.66

$2020-09-15 23:21:40, 6890537, 7488002, 0.4504004, 0.4360, 37.73556, 32.90417, 100.3, 7.66

$2020-09-15 23:21:42, 6890700, 7488091, 0.4514685, 3.1003, 37.69894, 32.91753, 100.3, 7.66

$2020-09-15 23:21:44, 6890863, 7488192, 0.4526644, 3.5079, 37.72641, 32.93088, 100.3, 7.66

$2020-09-15 23:21:46, 6891009, 7488308, 0.4539852, 3.8455, 37.76455, 32.94423, 100.9, 7.66

$2020-09-15 23:21:48, 6891181, 7488379, 0.4539719, -0.0397, 37.71267, 32.91753, 99.6, 7.66

$2020-09-15 23:21:50, 6891322, 7488435, 0.4555502, 4.6042, 37.64859, 32.93088, 100.3, 7.66

$2020-09-15 23:21:52, 6891469, 7488522, 0.4567795, 3.5648, 37.67300, 32.93088, 100.3, 7.66

$2020-09-15 23:21:54, 6891617, 7488534, 0.4580860, 3.7495, 37.66232, 32.93088, 100.3, 7.66

, which is in ppb).

ObservAir

Operating Manual