Campbell Scientific TDR100 Time Domain Reflectometry Systems - Manual (Page 25)

TDR100
SDMAddress: The SDMAddress parameter defines the address of the
TDR100 with which to communicate. Valid SDM addresses are 0 through 14.
Address 15 is reserved for the SDMTrigger instruction. If the Reps parameter
is greater than 1, the datalogger will increment the SDM address for each
subsequent TDR100 that it communicates with.
CRBasic dataloggers use base 10 when addressing SDM devices.
Edlog programmed dataloggers (e.g., CR10X, CR23X) used
base 4 for addressing. NOTE
Option: The Option parameter determines the output of the instruction.
Code Description
0 Measure La/L (ratio of apparent to physical probe rod length)
1 Collect Waveform values - Outputs reflection waveform values as an
array of floating point numbers with a range of -1 to 1. The
waveform values are prefaced by a header containing values of key
parameters for this instruction (averaging, propagation velocity,
points, cable length, window length, probe length, probe offset,
multiplier, offset)
2 Collect Waveform plus First Derivative - Returns (2*n-5)+9 values
where n is the number of waveform reflection values specified by the
Points parameter.
3 Measure Electrical Conductivity - Outputs a value that when
multiplied by the Multiplier parameter determines soil bulk electrical
conductivity in S/m.
Mux/ProbeSelect: The Mux/Probe Select parameter is used to define the setup
of any multiplexers and attached probes in the system. The addressing scheme
used is ABCR, where A = level 1 multiplexer channel, B = level 2 multiplexer
channel, C = level 3 multiplexer channel, and R = the number of consecutive
probes to be read, starting with the channel specified by the ABC value
(maximum of 8). 0 is entered for any level not used.
WaveAvg: The WaveAvg parameter is used to define the number of
waveform reflections averaged by the TDR100 to give a single result. A
waveform averaging value of 4 provides good signal-to-noise ratio under
typical applications. Under high noise conditions averaging can be increased.
The maximum averaging possible is 128.
Vp: The Vp parameter allows you to enter the propagation velocity of a cable
when using the instruction to test for cable lengths or faults. Vp adjustment is
not necessary for soil water content or electrical conductivity measurement and
should be set to 1.0 for output Option 1, 2, or 3.
Points: The Points parameter is used to define the number of values in the
displayed or collected waveform (20 to 2048). A entry of 251 is recommended
for soil water measurements. The waveform consists of the number of Points
equally spaced over the WindowLength.
CableLength: The CableLength parameter is used to specify the cable length,
in meters, of the TDR probes. If a 0 is entered for the Option parameter, cable
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