Campbell Scientific TGA100 Trace Gas Analyzer Manual - Manual (Page 41)

Table 6. Gradient File Contents
Day Day of year, with January 1 written as 1
Time Time of day, in 24 hour format. For example 6:15:01 AM is written as 06:15:01, and 6:15:01
PM is written as 18:15:01.
Site Site number, from 1 to 18.
M/S ID Master/slave identifier. This column includes a number, 0 through 4, to identify data from the
master TGA100, which always controls the sampling system, and slave TGA100s, which may
share a sampling system as described in section 5.3. If the analyzer is in dual ramp mode, this
field will also include "A" or "B" to differentiate between ramp A data and ramp B data. If the
TGA100 is not in dual ramp mode and there are no slave TGA100s attached this column will
always be 0. The number of slaves recorded in the file is set by the "Number of slaves attached
to this TGA" parameter, as described in section 5.3.
# Scans: Number of scans included in the calculations, where a scan is a measurement of level 1 and
level 2.
Level 1 Mean
Conc. (ppm) The mean trace gas concentration, in ppm, calculated from the measurements that are valid for
level 1.
Level 1 Conc.
Slope (ppm/scan) The time rate of change of trace gas concentration, in ppm/scan, for level 1.
Level 1 Mean
Pressure (units) The mean sample pressure, calculated from the measurements that are valid for level 1. The
pressure is given in units defined by the "Units for pressure measurement" parameter on the
Pressure Calculation screen.
Level 1 Standard
Deviation Standard deviation, in ppm, of the samples used to calculate the mean concentration for level 1.
Level 2 Mean
Conc. (ppm) The mean trace gas concentration, in ppm, calculated from the measurements that are valid for
level 2.
Level 2 Conc.
Slope (ppm/scan) The time rate of change of trace gas concentration, in ppm/scan, for level 2.
Level 2 Mean
Pressure (units) The mean sample pressure, calculated from the measurements that are valid for level 2. The
pressure is given in units defined by the "Units for pressure measurement" parameter on the
Pressure Calculation screen.
Level 2 Standard
Deviation Standard deviation, in ppm, of the samples used to calculate the mean concentration for level 2.
3.6.4 Site Means Files
Site Means data are saved by enabling the Site Mean measurement function by pressing the <S> Quick key from the
real time screen. This creates a file called MMDDHHMM.SM, stored in the default data directory. The Site Means
measurement mode is discussed in section 5.2.
Data are saved at the end of the sequence. The duration of the sequence is set by the user, in the Output Interval
parameter, as discussed in section 5.2. The time of day (and the day of year) are based on the PC real-time clock, at the
time the data are written to the file. Thus it represents the end of the averaging period. Also, because the timing of the
site means sampling sequence is driven by the clock in the analyzer electronics, the time of day reported in the file may
drift over time. For example, if the sequence time is 1 hour, the data at the start of the file will be written on the hour,
but if the PC clock is “fast” compared to the TGA100 clock, the data will eventually be written at one minute past the
hour, then two minutes past the hour, etc.
This file is always ASCII (plain text) format. The first three rows contain header information, and the rest of the file
contains the data. The contents of the file are listed in Table 7.
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