Spectrum fieldscout TDR 300 User manual

TDR 300
Soil Moisture Meter
PRODUCT MANUAL
Item # 6430FS
®

2
CONTENTS
General Overview 3
Shaft Dimensions 4
Computer Interface/Changing Batteries 5
Identifying the Correct Com Port 6
Meter Operation 7
Meter Calibration 10
Taking Readings 11
Field Scout Software Toolbar 14
Meter Settings 16
Connecting to a GPS Unit 18
Data Files 20
Volumetric Water Content Measurements 22
Relative Water Content 24
Specifications 26
Appendix 1: Time Zone Corrections 27
Appendix 2: Soil-Specific Calibration 28
Appendix 3: Troubleshooting 30
This manual will familiarize you with the features and operation of
your new FieldScoutTM TDR 300 Soil Moisture Meter. Please read
this manual thoroughly before using your instrument. For customer
support, or to place an order, call Spectrum Technologies, Inc. at
[phone] or [phone]
between 7:30 am and 5:30 p.m. CST
FAX [phone]
e-mail: [email protected]
www.specmeters.com

3
Thank you for purchasing the Field ScoutTM TDR 300
Soil Moisture Meter. This manual describes the fea-
tures and operation of the meter.
Soil moisture is a critical and potentially highly vari-
able component of the soil environment. Time-domain
reflectometry is a proven technology for quickly and
accurately determining volumetric water content
(VWC) in soil.
The Field Scout’s shaft-mounted probe allows the user
to easily and rapidly take many measurements. The
user can quickly transition between taking VWC read-
ings in standard and high-clay mode. The meter’s
built-in data logger can record data from several sites
and eliminates the need to record data manually.
Through the software (included) the user can download
the data, change the logger settings and program the
logger to record relative water content at multiple sites.
Contents
Your TDR300 shipment includes the following compo-
nents:
- TDR 300 meter (in retracted position)
- Carrying case
- Wrench for tightening rods
- 4 AAA batteries
- Field Scout software installation CD
- Gray PC interface cable
Note: TDR rods are sold separately
General overview

4
Shaft dimensions
1.3”
3.0”
3.1”
The following are the dimensions of a fully extended
shaft. It is possible to reduce the length of the meter by
2” (5cm) by adjusting the lower half of the shaft.
14”
4”
20”
16”
Meter

5
TDR 300
data port
Software Installation
Insert the CD for Field Scout software into your PC’s disk
drive. If auto-start is not enabled on your computer, select
Run from the Start menu and type D:\Setup.exe
(Substitute the appropriate drive letter for your CD drive).
Click OK and follow the instructions on the screen.
The data port on the underside of the TDR 300 meter
(shown above) can be accessed by removing the plastic
screw. It is through this port that the meter is connected
to either a PC or to a GPS unit. The meter must be turned
off before attempting communication with the software.
Connecting to a PC
The Field Scout software comes with a gray PC interface
cable. This cable connects to the 9-pin serial port of your
computer and to the meter’s computer port. The meter’s
configuration can be modified by clicking on the Meter
Settings button (see Meter Settings, p. 16). The Com
Port, Meter Type, Download, Clear Memory and Me-
ter Settings buttons are explained in the Field Scout Soft-
ware Toolbar section (p. 14).
Changing the batteries
The battery compartment is accessed by removing the me-
ter’s face plate. The meter is powered by AAA batteries.
When installing new batteries, note whether the bat-
teries immediately feel hot to the touch. The battery
has been short-circuited and should be replaced.
Computer Interface/
Changing Batteries

6
NOTE: The dataloggers do not short-circuit the serial pin.
Therefore, when the Test Port button is clicked while the
meter is connected, the “No Connection” message will be
displayed.
The computer
Communications Port to
which the PC-3.5 serial
cable is connected can be
identified by using a
paper clip.
1. Disconnect the serial
cable from the meter.
2. To bring up the Port Selection screen, click on the
Com Port Button, select the com port to be tested and
click the Port Test button. Click the Test Port Now
button. If the message “Connection OK” is displayed,
another device (such as a modem) is probably connected
to that port. If the message “No Connection” is displayed,
this port may be the one connected to your serial cable and
you can proceed to the next step.
3. Place a paperclip on the end of the serial pin so that it
touches both the tip of the pin and the metal area between
the two black rings. Again click on the Test Port Now
button. If the message “Connection OK” now appears,
this is the com port connected to your serial cable.
paper clip
or wire
Identifying the
Correct Com Port

7
Meter Operation
The ON switch turns the meter/
datalogger on and off. When the meter is
turned on, it will display the battery
status for 3 seconds. For the next 3 sec-
onds, it will display how much logger
memory has been used and, if the logger was enabled in
the software, whether the GPS signal was found. If a GPS
signal is found, latitude and longitude data will be in-
cluded in the data file. The screen will then display the
most recently used MODE screen.
ON
Logger 75% Full
GPS=Yes DGPS=No Logger 75% Full No GPS Found
Sample meter power-up screens with datalogger
enabled: left screen indicates GPS signal was found.
If you are using GPS, but the meter doesn’t find the GPS
signal when powering up, the meter will not search for the
GPS signal when taking readings. Turn the meter off and
on so it can look for the GPS signal. Once the signal is
found, GPS information will be included in the data file
until the signal is lost or the GPS unit is disconnected
from the meter.
Note: If the data logger is disabled (see Meter Settings, p.
16), the meter will not seek the GPS signal when it is
powered up. It will, instead, proceed immediately to the
most recently used mode (see MODE button, p. 8) screen.

8
MODE
Pressing the MODE button allows the
user to determine the type of measure-
ment that will be taken or select the
length of rods connected to the probe.
Data Collection Modes
Available measurement options are volumetric water con-
tent (VWC) using the standard or high clay mode (see p.
22), up to two relative water content modes (see p. 24), or
measurement period (in microseconds). Relative water
content options will only appear if they are configured in
the software (see Meter Settings, p. 16). The period meas-
urement is available for users interested in performing
soil-specific calibrations (see Appendix 2).
Note: There is not a high clay measurement calibration for
the 1.5” rods. The meter will display dashes if this mode/
rod length combination is selected.
Changing Rod Length
In order to get accurate volumetric or relative water con-
tent (VWC or RWC) readings, the rod length setting must
be correct. In the VWC modes, the currently selected rod
length appears in the lower left corner of the LCD screen.
The options are Turf (1.5”), Short (3.0”), Medium (4.7”),
and Long (7.9”) rods. Press the MODE button until the
LCD displays the rod length options screen. Pressing the
DELETE/CLR AVG button will allow you to toggle be-
tween the three choices.
MODE
ROD=MED (4.7in)
HIT DEL To Chnge
Rod Length Options Screen

9
Press the READ button to read the
probe and update the screen values.
Data values, along with GPS or DGPS
information if applicable, are sent di-
rectly to the data logger. If the logger
searches for, but doesn’t find a GPS signal, an error
message will briefly appear in the lower right corner.
In this case, a data point will be stored without the GPS
data. The data point can be cleared from memory with
the DELETE/CLR AVG button (above).
When the data logger is full, the LCD will display the
message “Error: Memory Full”. To resume normal op-
eration, the logger memory must be cleared using the
Clear Memory button in Field Scout software (see p.
15)
READ
When the DELETE/CLR AVG
button is pressed and immediately
released, the last data point will be
taken out of the logger file and
removed from the running aver-
age. Pressing and holding this but-
ton will reset the running average but will not affect
data stored on the data logger.
Delete
Clr Avg
Meter Calibration Mode
This mode allows you to calibrate the meter. The cali-
bration procedure is performed in air and distilled water
(see Meter Calibration, p. 10). Requires firmware v. 6.5
or greater.
CALIBRATION MODE
HIT READ To Cal
Meter Calibration Screen

10
The meter has internal calibrations for standard and
high-clay soil types. These calibrations will work for a
large number of soils. However, each meter will have a
small difference in how it responds to identical soil
conditions. This is due to sensor drift or variability in
the electronic components used during manufacturing.
Meters with firmware v. 6.5 or greater allow for adjust-
ments to the meter calibration to account for these dif-
ferences. Therefore, if two meters are giving slightly
different readings in the same soil, the output of the
meters can be standardized such that the meters can be
used interchangeably. The calibration procedure is as
follows:
1. Use the MODE button to put meter in Calibration
mode (see p. 8). Hit the READ button
2. Hold the meter so the rods are in the air. Press the
READ button and wait until the meter indicates it is
ready.
3. Immerse the rods completely in distilled or de-
ionized water. The container should have a minimum
diameter of 3 inches. Press the READ button and wait
until the meter indicates it is ready.
The meter will then show that the calibration is com-
plete for that specific rod length. If more than one rod
size is being used, a calibration operation must be done
for each one.
Note: This procedure is different than a soil-specific
calibration (Appendix 2, p. 28) where a unique calibra-
tion curve is generated.
Meter Calibration

11
Taking Readings
- Remove one of the
hand screws from the
shaft. This will allow
you to unfold the shaft
to its full length. Re-
turn the screw to lock
the shaft in the ex-
tended position.
- Screw the rods into
the sockets at the bot-
tom of the probe block.
- Turn on the meter and ensure that it is configured with
the correct rod length setting (see Changing Rod Length,
p. 8).
- Select the correct mode setting (see Data Collection
Modes, p. 8). This will bring you to one of the data col-
lection screens. The TDR 300 can be set to one of two
VWC modes, Standard or High Clay.The Standard
mode will be appropriate for most mineral soils. The
High Clay mode will be more accurate for soils with
higher clay contents (>27%). In VWC mode, the top
line of the display shows the VWC mode and the water
content. The bottom line has probe setting and data file
information.

12
PL: Probe Length (Turf,
Short, Medium, or Long rods)
N: Number of readings included in the Average
A: Average of all readings taken since meter was
turned on or DELETE/CLR AVG button was
pressed
Note, the internal calibrations are valid for a wide range of
mineral soils. However, for soils that are high in clay, or-
ganic matter or salt, the meter will give values that are
higher than the actual VWC. In this case, it is recom-
mended that the meter be operated in relative water content
mode (see p. 24) or that a soil-specific calibration be devel-
oped (see Appendix 2).
The meter can also be set to give the raw reading if it is set
to Period mode. This mode is intended primarily for soil-
specific calibrations.
- Push the rods into the soil. When taking a measurement, it
is important that the rods be fully inserted into the soil. If
not, part of the sampling volume will be composed of air
and the reading will be inaccurately low. For the same rea-
son, the probe should be inserted with a steady, downward
pressure. If the rods are wiggled into the soil, air pockets
can be created adjacent to the rods that will result in low
readings. The probe should not be struck with a hammer or
other blunt instrument as this can cause damage to the inter-
nal electronics. Also, care should be taken to ensure the
rods are inserted as parallel to one another as possible. This
STNDRD VWC%=35.1
PL=S N015 A=36.3
Sample Data Screen

13
will not have a large affect on the reading but will de-
crease the chances the rods will be bent or broken. Like-
wise, it is best to avoid areas with rocks or other material
that can cause the rods to deflect or bend. If the ground
is especially hard or compact, you can use a Pilot Hole
maker (item 6430PH) to make 1½” holes to aid in start-
ing the insertion of the probe rods.
- Press the READ button to initiate the measurement se-
quence. The reading should appear almost instantane-
ously.
Note: The TDR rods are manufactured from type 303
stainless steel and are designed to bend if non-vertical
force is applied to them. This serves to protect the TDR
block electronics from potential damage that could be
caused by excessive force.
Occasional rod bending is normal, and can be expected
during the course of sampling. Longer rods will be more
susceptible to bending than shorter rods. If bending oc-
curs, rods should simply be bent back to parallel position,
perpendicular to the TDR block. Measurements will
continue to be accurate provided that rods are reasonably
close to parallel.
If care is not taken to reposition rods to a parallel posi-
tion, subsequent pressure on the rods will accentuate the
bending and may cause the rods to break. Rods should
be considered maintenance items that may need to be re-
placed over time, depending upon the nature and fre-
quency of sampling.

14
Com Port
The gray software cable con-
nects the meter to the computer
data port. Select the Com Port
that is assigned to the computer
data port. See Identifying the
Correct Com Port (p. 6) for in-
structions on how to determine
which port to select.
Meter Type
Select the TDR option from the
list of available Field Scout me-
ters.
Field Scout
software Toolbar

15
Download
To download data from the internal data logger, turn the
meter off and connect the gray serial cable to the RS-232
port on the underside of the meter. Click the Download
button on the main software screen. In the Save Data As
screen, give the file a descriptive name and select the loca-
tion where it will be saved.
When the file has been saved, the software will give you
the option of immediately viewing the file. The data file
is stored as a comma-delimited text file and may be
viewed in text editor or spreadsheet software.
Clear Memory
Data is not automatically removed from the logger mem-
ory after a download. The Clear Memory button clears
all data from the logger memory.
Meter Settings
Click this button to configure the meter and data logger.
Refer to “Meter Settings” (p. 16) for more details.

16
Meter Settings
The Meter Settings screen in the Field Scout software
is used to configure the meter and data logger for your
specific application. The fields are described below.
Meter Name: The name given the meter will be the
title on the first line of the downloaded text file.
Logger Settings: The data logger is enabled and dis-
abled by checking the first box. If the data logger is
enabled, it will search for a GPS signal when the meter
is turned on. If a signal is found, position data will be
stored along with the soil moisture data. If no GPS sig-
nal is available when the logger is turned on, the logger
will no longer look for one when measuring and re-
cording soil moisture data. If the second box is
checked, the logger will store the GPS value only if it
has been differentially corrected. In general, this op-
tion should remain unchecked. If the differential cor-

17
rection is not found, only the soil moisture value will be
stored in the data file. A time-zone correction should be
entered in the third box.
Units: When operating the meter in Relative Water Con-
tent mode, the LCD can display the rod length options in
English or metric units. The meter will calculate and dis-
play the water deficit (see Relative Water Content p. 24)
in the same unit system.
Relative Water Content Set Points: Up to 2 Relative
Water Content (see p. 24) modes can be programmed into
the meter by entering the wet and dry set points into the
appropriate boxes. From the dropdown menus near the
bottom of the screen, select which VWC calibration
(Standard or High Clay) should be used for each RWC
mode. Each of these modes can be given a descriptive
name of 5 characters. These names can be used to iden-
tify a certain field or soil type.
Finally, for an RWC mode to be available, it must be en-
abled by checking the Enable Display box. If this box is
not checked, that RWC mode will not appear on the LCD
during meter operation.

18
The data logger function must be enabled using the Field
Scout software in order to record a GPS signal (see Meter
Settings p. 16).
The GPS unit must be plugged into the TDR 300 meter
and running when the meter is first turned on. If a GPS
signal is found at startup, the logger will search for a GPS
signal for every reading. If no GPS signal is found when
the meter is first turned on, the meter will not search for
one when taking readings, thereby saving time when tak-
ing readings. In this case the LCD will display the No
GPS Found message.
If the GPS signal is found while taking geo-referenced
readings, the LCD will briefly display the message,
“Reading GPS ..” before displaying the measurement. If
the GPS signal is lost during a series of readings, or if the
specified differential correction is not found, the LCD will
read “Reading GPS .. ERR” before returning to measure-
ment mode. In this case, the data will be recorded without
latitude and longitude. During subsequent readings, the
meter will again search for a GPS.
GPS Setting
Your GPS unit must be set for NMEA 0183 input/output
messages. If the meter has trouble receiving the GPS sig-
nal, check that it has the following settings:
Data bits: 8 Stop bits: 1
Baud rate: 4800 bps Parity: None
Timing: 1 second GGA data string
Connecting to a
GPS Unit

19
GPS computer
interface cable
Spectrum
GPS/DGPS
Cable
TDR
300
Meter
GPS
Unit
Connecting the TDR 300 meter to a GPS unit
Cable Connections
A GPS/DGPS cable (item # 2950CV5) is required to con-
nect the TDR 300 meter to a GPS unit. This cable has a
9-pin male connection and a stereo pin that connects to the
meter’s data port. You will also need a cable that allows
the GPS unit to connect to a 9-pin male serial port. If this
cable doesn’t come standard with your GPS unit, it should
be available from the manufacturer. This cable is gener-
ally used to upload information from a computer to the
GPS unit. These components should be connected as
shown in the figure below.

20
The data is stored in comma-delimited text files. These
files can be opened with text-editing software (e.g. Micro-
soft Word) or spreadsheet software (e.g. Excel).
The first two lines of the data file give the logger’s name
and serial number. The third line indicates that latitude
and longitude are referenced to the 1984 World Geodetic
Survey datum. The fourth line shows the column head-
ings for the rest of the data file.
Logging sessions are started and completed by turning the
meter on and off. The start of a logging session is indi-
cated by the data line “Logger Started.” If a GPS signal
was found at the start of a logger session, a time stamp is
included on the “Logger Started” line.
Sample data showing results of data collected with and
without GPS activated. Note: GPS signal not found
when recording data in lines 17 through 26.
Data Files