Campbell Scientific TDR100 Time Domain Reflectometry Systems - Manual (Page 38)

TDR100
9.2.2 Algorithm Parameter Adjustment for Special Conditions
The standard settings for the apparent length algorithm work well for nearly all
applications. For special cases of very long cables or some probes that are not
manufactured by Campbell Scientific an algorithm parameter change can
improve results. The parameter discussed here affects how the algorithm finds
the beginning of the TDR probe.
9.2.2.1 Terminal Emulator Commands for Apparent Length Algorithm
There are two commands associated with the apparent length algorithm.
GMOP will get and display current parameter setting. SMO1 x.xx sets the
apparent length parameter to decimal value x.xx. The default value is 0.25 and
the range is 0.05 to 1.0.
>
See operating manual for command descriptions
Press Enter for > prompt
***************************************
Electrical conductivity parameters
SEC1 xx Set EC Parameter 1
SEC2 xx.xx Set EC Parameter 2
SEC3 xx.xx Set EC Parameter 3
SEC4 xx.xx Set EC Parameter 4
GECP Get EC Parameters
***************************************
*************************************************
Apparent length parameters
SMO1 0.xx Set Apparent Length Threshold
GMOP Get Apparent Length Parameters
***************************************************
SSU Save Changes to EEPROM
FIGURE 9-2. PCTDR terminal emulator screen showing TDR100
algorithm parameter variables.
The SMO1 parameter alters the part of the algorithm that finds the beginning
of the probe. In cases where the amplitude of the waveform at point 2 as
shown in Figure 9-1 is low, reducing the SM01 value makes the algorithm
more sensitive. Reduced amplitude at point 2 can result from signal losses in
long probe cables. Increasing the SM01 value can help when noise is present.
When adjusting SM01, do so in small increments, e.g. 0.05. When the correct
value is found, enter command SSU to write the value to memory.
32