CSV Data Format
bcMeter stores measurement data as CSV files. This page documents the file format and column definitions.
File Format
| Property |
Value
|
| Delimiter |
Semicolon (;)
|
| Encoding |
UTF-8
|
| Decimal separator |
Dot (.)
|
| Line ending |
LF (\n)
|
| First row |
Column headers
|
Filename Convention
- Active session:
YY-MM-DD_HHMMSS.csv (based on session start time)
- Fallback (no RTC sync):
nosync_HHMMSS.csv (based on uptime)
Column Definitions
Core Columns (always present)
| Column |
Type |
Unit |
Description
|
bcmDate |
string |
DD-MM-YY |
Measurement date
|
bcmTime |
string |
HH:MM:SS |
Measurement time
|
bcmRef_880nm |
float |
V |
Reference channel voltage (880nm LED through clean filter)
|
bcmSen_880nm |
float |
V |
Sensor channel voltage (880nm LED through sample spot)
|
bcmATN_880nm |
float |
— |
Attenuation at 880nm = −ln(Sen/Ref) / σ
|
BCngm3_unfiltered_880nm |
float |
ng/m³ |
Real-time BC concentration (unsmoothed)
|
BCngm3_880nm |
float |
ng/m³ |
BC concentration with rolling average applied
|
relativeLoad |
float |
% |
Filter loading (0 = clean, 100 = saturated)
|
AAE |
float |
— |
Ångström Absorption Exponent (requires multi-wavelength)
|
Temperature |
float |
°C |
Internal device temperature
|
airflow |
float |
L/min |
Measured airflow rate
|
Multi-Wavelength Columns (optional, if hardware installed)
Same structure as 880nm, repeated for each wavelength:
bcmRef_520nm, bcmSen_520nm, bcmATN_520nm, BCngm3_unfiltered_520nm, BCngm3_520nmbcmRef_370nm, bcmSen_370nm, bcmATN_370nm, BCngm3_unfiltered_370nm, BCngm3_370nm
Environmental Columns (optional, sensor-dependent)
| Column |
Type |
Unit |
Description
|
humidity |
float |
% |
Relative humidity (BME280/SHT4x)
|
hPa |
float |
hPa |
Atmospheric pressure (BME280)
|
PM2.5 |
float |
µg/m³ |
Particulate matter <2.5µm (SPS30)
|
PM10 |
float |
µg/m³ |
Particulate matter <10µm (SPS30)
|
GPS Columns (optional, if GPS module connected and has fix)
| Column |
Type |
Unit |
Description
|
lat |
float |
degrees |
Latitude (WGS84)
|
lon |
float |
degrees |
Longitude (WGS84)
|
altitude |
float |
m |
GPS altitude above sea level
|
Metadata Columns
| Column |
Type |
Description
|
notice |
string |
System notices or warnings per data point
|
sampleDuration |
float |
Actual measurement duration for this sample (seconds)
|
notes |
string |
User-added annotations
|
Example Data
bcmDate;bcmTime;bcmRef_880nm;bcmSen_880nm;bcmATN_880nm;BCngm3_unfiltered_880nm;BCngm3_880nm;relativeLoad;AAE;Temperature;airflow
04-03-26;19:37:09;0.9679;0.9321;3.76;1686;1686;0;0;0;0.4659
04-03-26;19:42:09;0.9745;0.9335;4.3;4028.5;1686;0;0;0;0.3088
04-03-26;19:47:09;0.9752;0.9315;4.59;2371.4;1830.2;0;0;0;0.2832
Import Notes
- Excel: Use "Text Import Wizard" and set delimiter to semicolon. The date format DD-MM-YY may need manual conversion.
- Python/Pandas:
pd.read_csv('file.csv', sep=';')
- R:
read.csv2('file.csv') (uses semicolon by default)