Campbell CS725, Инструкция по эксплуатации

Страница: 44 / 56

CS725 Snow Water Equivalent Sensor
A-9
[13] N0Tl
This site specific parameter is used in the calculation of SWE. It represents
the integrated gamma ray count rate for the Thallium
208
Tl isotope peak, with
no snow cover and dry soil. This number is of course dependent upon the
level of natural radio-activity of the soil at the installation site. It can only be
calculated on the site. The auto-calibration method is a tool to obtain the first
estimate of that parameter. The format is an integer.
[14] n00Tl ( residual Tl counting)
This is a parameter to account for the gamma rays coming from above the
surface of the snow. It affects the SWE evaluation only under high SWE
conditions (>300 mm.). This value is normally determined after the 1
st
year
of operation. The value is typically 1900 or less.
[16] SN Threshold for the snow cover
This parameter is a threshold above which the normal calculation of the SWE
will be performed. The threshold is applied to a calculation of the last five
averaged SWE data based on the ratio of K/Tl, which is independent of the
humidity of the soil, but less accurate than the SWE measured from the K and
Tl information independently. When the averaged SWE calculated from the
K/Tl ratio is higher than the threshold, it is assumed that there is a snow
cover. The nominal humidity parameter is then used for the calculation.
Otherwise, the snow cover is assumed to be zero, and the CS725 calculates
the humidity of the soil. The default value is 5 mm.
[17] Baud rate for scheduled transmissions
This parameter defines the baud rate to be used for the automatic data
transmissions. In interactive mode with a terminal, the CS725 can adjust to
the terminal’s baud rate by typing “UU<Enter>”. However, for scheduled
transmissions, the CS725 will use the baud rate specified by this parameter.
This is for the cases when an interactive terminal used for the configuration
of a site is disconnected and replaced by the normal communication device
(modem, satellite, datalogger) with a different baud rate. This guarantees that
the scheduled transmissions will be done at the proper baud rate for the
communication device. The default rate is 9600 BAUD. Valid values for
this parameter are:
1200, 2400, 4800, 9600, 19200, 38400, 57600, and 115200.
[18] Number of hours per partial histo (hours),(1,2,3,or 6)
It is highly recommended to leave this setting to 1 h. It is recommended to
contact Campbell Scientific technical support prior to using other values.
In normal operation 1 h histograms generate, 24 partial histograms per day.
However, under very large snow packs (> 500 mm), the absorption of the
gamma rays is such that the peaks do not stand up much above the cosmic
radiation background after one hour of counting. In this case, the peak
identifying mechanism may fail. To overcome this situation, it is possible to
have histograms generated in periods of 2,3, or 6 hours.
[19] Manual mode (1); Auto mode (0) ; HCalib mode (2);
This parameter defines the operating mode of the CS725. In the Manual
mode (code =1), the CS725 will accumulate a histogram from the
initialization cycle until a manual command is sent to delete it. No
calculations of SWE will be performed, and no results transmission will be
scheduled. This mode is used when setting up the CS725 (i.e. verifying the
peak positions, modifying parameters, setting the time, etc.).